CRISPRi-ME prevents evolutionary failure of a burdensome plasmid in E. coli.
It reduces the rate of evolutionary failure but does not prevent
CRISPRi-ME prevents evolutionary failure of a burdensome plasmid in E. coli.
It reduces the rate of evolutionary failure but does not prevent
SDS in loading buffer may contribute to band smearing in precast GelRed® gels. If this occurs, we recommend using the post-staining protocol
50 μg/ml RNase (ThermoFisher #EN053) freshly added. 2 ml of lysis buffer
Fresh RNAse is really critical. Otherwise this will result in 10 fold more RNA contaminant than DNA; which implies the nanodrop reading and gel visualized DNA will be 10 - 100 fold different. (from personal experience of 1 prep only)
deep-well plates, require a faster shaking speed for proper aeration
Deepwell plates (24 well plates with 3ml cultures as well as 96 well with 1 ml) require 800 rpm shakers
Composition of H15 growth medium
valorization of waste chemicals accumulating in industry is one of the pillars of the circular economy and the 4th Industrial Revolution
we recommend calibrating OD using serial dilution of silica microspheres, which readily produces highly precise calibration (95.5% of teams having residuals less than 1.2-fold), is easily assessed for quality control, and as a side effect also assesses the effective linear range of an instrument.
Bacteria are less likely to develop resistance against a pro-drug as it becomes active only after getting inside the bacteria. The active components formed from the pro-drug are potent and short-lived, thus not giving the bacteria sufficient time to develop resistance.
Would like to see some evidence for this!
which ends up being much less efficient
Has this been quantified properly? I see a lot of new methods relying on in-vivo homologous recombination now-a-days - ex: FastCloning: a highly simplified, purification-free, sequence- and ligation-independent PCR cloning method
“death phase,” where at least 99% of the cells in the culture lose viability
So the 'death' in death phase is only loss of viability?
I thought the cells lyse and are eaten up by neighbours; while reducing the OD (due to cell lysis)
E. coli in 2xYT broth which takes faster (8 h) to grow compared to LB
this system enables longer duration production, and could be readily applied to burdensome or toxic products not readily produced in bacteria
Application of synthetic biology is limited by the capacity of cells to faithfully execute burdensome engineered functions in the face of Darwinian evolution
sequential lineage tracing studies aimed at unraveling the relationships between cellular precursors and mature cell types
To add a data mask so you can refer to variables in a data frame as if they are variables in an environment.
Similar to a with() function?
plasmid-based circuits suffer from multiple limitations: high intercellular variation in gene expression, genetic instability from random partitioning of plasmids during cell division, and plasmid loss in environments for which antibiotic use could disrupt native microbial communities or is economically infeasible
, science proceeds by the falsification and refinement of hypotheses. Thus, for most papers, the only way is down.
That one nails it!
despite Blatt’s carefully worded insinuations, PubPeer does not allow “hearsay”, “allegations” or invite “innuendo” (and we aim to act on all reports of such comments)
Blatt does mention that the pubpeer site moderators are anonyomous in contrast to the journal editors. This somehow reduces their credibility on effective moderation of abusive or trolling comments. This sounds like a recursive argument: A central authority brings credibility but also corruptibility. I can see parallels in the debate about Bitcoin cryptocurrency vs federally backed currency and about the trustworthiness vs corruptibility of a central authority as compared to a distributed crowd authority.
authors, journals and institutions are all unquestionably exposed to conflicts of interest when it comes to correcting problems
A retraction once published does not reflect well on all of these parties and is clearly a conflict of interest even though they may claim that it is in their benefit. Somehow a pre-publication review is being given more importance than a post-publication review because of this reason.
in much of biology, readers have to trust the authors to describe their experiments accurately, and there are many more opportunities for mistakes and dishonesty
Good point
alleging their negative appraisals of his work had resulted in a university rescinding a job offer
Oh, and what does he have to say about the 20 retractions he as so far then?
I is like a real wrongdoer criticising the police for investing in the first place.
Commenting on a scientific paper, in particular when the comments are not positive, is risky business for academics
Could someone elaborate on this? Why exactly does negative commenting cause a researcher to be discriminated against?
auxotrophic for specific amino acids
That means gram-negative bacteria cannot change the BamA protein without losing their ability to infect.
It 'suggests' that would have been better. There might also be other resistance pathways that might retain infectivity. This will depend on the environment used for the resistance evolution experiment
Reference values for the Z-position
5 nM fluorescein in 0.01 M NaOH was measured in black 96-well microplates
(a+b+c)^2 - a:b is identical to a + b + c + b:c + a:c
This example is not clear. I do not understand what a:b means
enquo() uses some dark magic to look at the argument, see what the user typed, and return that value as a quosure
landscape vs. portrait.
slides are landscape, reports are portrait!
Ina Schuppe Koistinen, Abhishek Krishnagopal, Sangeetha Kadur, Pooja Gupta etc gave me the inspiration to do what I wanted to do. Along the way I got exposed to more art and science creators like Gemma Anderson, Monica Zoppe, Drew Barry, Ina S. Koistinen, Christian Sardet, Sandra Black Culliton, Amanda Phingbodhipakkiya
science communication - art + science
we present an overview of our current understanding of these rules for the genetic manipulation of prokaryotic microbes and the available genetic tools to expand our ability to genetically engineer nonmodel systems
s used fluorescein-labelled oligonucleotides as our probe for DNA delivery
DNA delivery assessment
required removal of salts results in osmotic stress - particularly challenging for a notoriously temperamental marine bacterium like Prochlorococcus
Electroporation buffers cause osmotic stress and need osmoprotectants like glycerol
the 6-month multi-step procedure is vulnerable to user variability
The doubling time is 3.3 days!
This cell is the simplest photosynthetic “machine” designed by nature – an attractive foundation for manipulation
small size (hence high surface/volume ratio), which enhances its ability to compete for limiting nutrients
Such projects are not suitable for graduate students or post-docs because of the high risk involved, nor are they easily funded
that is wisdom!
genetic transformation protocols requires tedious trial and error, and methods developed for one strain are often unsuccessful in close relatives
To avoid the pursuit of unproductive paths, we report here what has not worked in our hands, as well as our progress developing a method to screen the most efficient electroporation parameters for optimal DNA delivery into Prochlorococcus cells
negative results
HGT typically adds new catabolic routes to microbial metabolic networks. This increases the chance of new metabolic interactions between bacteria
key attributes needed to produce a worthy PhD thesis are a readiness to accept failure; resilience; persistence; the ability to troubleshoot; dedication; independence; and a willingness to commit to very hard work — together with curiosity and a passion for research
key challenge is to quantify the functional roles of bacterial taxa in nature to understand how the properties of ecosystems change over time or under different environmental conditions
Hemicellulase activity was elevated in pairwise mixtures of communities that placed interacting phylotypes together (interactions, n = 9 mixtures) but not in communities that did not place interacting phylotypes together (no interactions, n = 56 mixtures)
Very interesting way to validate correlative phenotypes in communities
For F-1 and J-1 students, on-campus work is limited to part-time (20 hours or less per week) during the fall and spring semesters when school is in session
Does RA count for 20 h?
tools described here can be used to mimic complex expression patterns, such as the ones found for pneumococcal virulence factors, paving the way for in vivo investigations of the importance of gene expression control on the pathogenicity of S. pneumoniae.
It is challenging to study how pneumococci control virulence factor expression, because cues of natural environments and the presence of an immune system are difficult to simulate in vitro
When you present information visually (using slides, a poster, video, handout, etc.), you must provide a full written citation.
citing sources
these two highly active enzymes were functionalized with an affinity binding motif through the genetic fusion of a carbohydrate binding module (CBM) from Cellulomonas fimi with specificity to cellulose (CBM2a)
Why should the enzyme be functionalized to bind cellulose, should the carbohydrate binding be on the phage capsid?
optical nanostructures, surface enhanced Raman spectroscopy, flow cytometry, etc.) have shown promise as sensitive detection methods, they typically process only small, relatively clean samples. The true bottleneck to rapid detection methods remains the separation of a target analyte from a large complex matrix.
EPA Method 1603 is an approved drinking water assay that quantifies generic E. coli
This drinking water assay contains a membrane (0.45 µm) filtration step to remove bacteria from the water sample prior to enrichment on selective and differential media. The bacteria CFUs are quantified directly on the filter following a lengthy enrichment
most probable number (MPN) method. The MPN is determined by serial diluting the water sample in triplicate or pentaplicate followed by incubation in selective growth media
single copy phylogenetic marker gene
How is this marker gene strictly single copy? How do you know?
known to introduce biases in composition estimates due to, for instance, variations in 16S rRNA gene copy numbers per genome
Are the other marker genes known to be single copy?
unequal efficiencies of PCR-primers in different species
This should presumably also affect your 40 housekeeping marker genes.
Students who are less exposed to what we propose here may resist at first, simply because it is unfamiliar, but it is our experience that, overall, students will embrace and appreciate these modifications to the way assessments are conducted.
The initial student resistance is a very good point
opening new paths for side effect control
This is a tall claim. Is the microbiome's contribution to side effects well studied? Is it a significant contribution compared to off target human pathways and pleiotropic effects?
Susceptibility to antibiotics and human-targeted drugs correlates across bacterial species
This is interesting
EDTA-extractable fraction
Why EDTA extraction? How does this compare with a water extraction?
we define the physiological and environmental parameters that mediate the transition from cooperation to competition
transient events
Need better examples of transient events
Illustration by Sébastien Thibault
Cool illustration! It does speak a 1000 words indeed
SDS affects the oligomerization state of Aβ42 oligomers, thus providing flawed information on their order and distribution.
The fact that SDS affects protein structures and oligomerization seems to be well known.
I thought people did a variant called 'native PAGE' where SDS is not added and the protein is treated in non-denaturing conditions. Did you compare your method to this?
except for those that catalyze irreversible reactions in the TCA, such as citrate synthase
Why is this irreversible
molecular explanations of whether such shifts represent cause or effect of the disease itself are limited
Graphical abstract
This is a decent graphical abstract compared to other engineering or wastewater papers
includes creation of innovative solutions for bio energy, resource recovery, and emerging public health concerns by leveraging synthetic or molecular biology tools, novel biological systems (genetic circuits, enzymes, genetically engineered microbes), fundamental biological and chemical concepts, artificial intelligence, and big data science, as well as collaborations in Computer Science, Public Health, Plant Biology, or related fields.
A biofilm was prepared
Biofilms are never prepared, they are grown!
biofilm
Wrong use of words. You should call it a layer of immobilized bacteria. Biofilm is when cells deliberately stick to a surface and secrete a matrix
values measured by using luminous E. coli had tendency of about 30–40% lower than that of BOD5, it could be observed an apparent correlation between the two values
I don't think this is robust correlation. It will depend on the organic composition of the BOD
bioluminescence was observed during the incubation time between 90 and 150 min in the presence of a sole carbon source such as glucose, acetate, l-glutamate and BOD standard solution (GGA solution)
So this is a limited BOD sensor for only the subset of organic compounds that E. coli can metabolize?
is dosed with seed microorganisms and stored for 5 days in the dark room at 20 °C to prevent DO production via photosynthesis
Does the BOD measurement and interpretation depend on the organism the sample is seeded with?
The generally lower values in the U.S. derive from the much greater water use per capita than in other parts of the world
Wow, that is amazing to know. Wonder how this cultural shift started historically?
not suitable for process control in wastewater treatment and the real-time monitoring of water environments, such as rivers, streams, ponds, and ground water
is independent of the general recombination pathway
What is this general recombination pathway?
it then moves in a directed path through the pore space, a process we call hopping
How is this different from the 'run'
Phase variation is often mediated by the presence of highly mutagenic simple tandem DNA repeats, and genes containing such sequences can be easily identified
ఎప్పటికైనా Knowledge Centric Value Based Education రావాలని కోరుకుందాం
I like the problem statement, but what is this knowledge centric value based education? Is this a good solution?
It is essential to realize that there is no magic bullet that can solve such a complex problem that is so central to our life, livelihood and the urban upper middle class (shall I call brahminical!?) way of life. There must be many solutions working together towards the same idea. But first we should be clear on the problem and acknowledge it!
observations are consistent with a previous report showing that AHLs preferentially partition to the biofilm, reaching concentrations 600-fold in excess of the signal concentration in the surrounding bulk liquid medium
the best way to correct for the analyte signal suppression or enhancement is to co-elute a stable isotope labelled (SIL) analogue of the analyte
It is not straight forward to get isotope labelled standards for every compound
We also show how our toolbox can be used to deploy the FBP in planta to build auto-luminescent reporters for the study of gene-expression and hormone fluxes
We tested a broad range of Enterobacteriaceae conjugative plasmids for their sensitivity to the growth stage of the donors and identified three distinct regulation types.
indicate that even low concentrations of just a single type of antibiotic leads to resistance to multiple classes of antibiotics.
I doubt this claim, do you mean they are correlated?
Overall, the low contamination level of antibiotics and high absolute abundance of ARGs indicated that ARGs previously introduced to an environment can self-amplify and persist in the environment
suggesting that STPs have become an important source of contamination for their receiving rivers
Read these references: Saying antibiotic resistance is proliferating in wastewater treatment plants
Additionally, the concentrations of antibiotics and the abundance of ARGs might increase after the sewage treatment process.
Wow, that is a strong and counter-intuitive claim. Is this rigorously determined?
Perhaps we ultimately need to be prepared to accept less standardised and slightly more expensive food in order to accommodate less intense and more diverse agriculture. You might never be quite sure what to expect when you peeled a banana, but the result could be a more robust and sustainable food system without a major crisis every few decades.
With this approach, neurons that show E-SARE–driven expression in response to stimuli are permanently labeled by the fluorescent protein during the time window specified by the drug
Expression of a drug-inducible Cre recombinase downstream of E-SARE enabled imaging of neuronal populations that respond to monocular visual stimulation and tracking of their long-distance thalamocortical projections in living mice
The feedback loop permits sustained induction of recombinant proteins without massive quantities of inducer.
We have demonstrated that small RNAs can tightly repress their target genes when their synthesis rate is smaller than some threshold, but have little or no effect when the synthesis rate is much larger than that threshold
a threshold-linear response with a tunable threshold, a robust noise resistance characteristic, and a built-in capability for hierarchical cross-talk.
In particular, small RNAs are shown to establish a threshold for the expression of their target, providing safety mechanism against random fluctuations and transient signals. The threshold level is set by the transcription rate of the small RNA and can thus be modulated dynamically to reflect changing environmental conditions.
in the absence of tamoxifen, it exhibits some activity
A technique common in rodents is the use of Cre recombinase lines that are inducible at specific developmental time points (Figure 3b). The most common form of inducible Cre is CreERT2, which contains a modified estrogen receptor binding domain that prevents Cre from entering the nucleus in the absence of a ligand
strong promoters capable of driving expression of microbial opsins or fluorescent proteins in specific populations can exhibit leaky expression elsewhere. This low-level leak may be virtually undetectable as light responsiveness or fluorescence but can be a serious issue when expressing Cre recombinase.
Our analysis demonstrates that its structure is shaped more by stochasticity than selection.
To investigate how ciprofloxacin 35resistance is affected by the presence of metals,
Ciprofloxacin's activity (MIC, IC50 etc.) could also depend on Zn presence, was this investigaged before going into selection and evolution?
creating improved technologies for large-scale recordings of neural activity in the live brain is a crucial goal in neuroscience
new toolkits for chronic labeling of active ensembles will provide a much awaited experimental basis to interrogate various aspects of neuronal circuits underlying long-term plastic changes of the brain, such as during nervous system development, during establishment of long-lasting remote memory over months, or in association with age-related neuronal changes over several years.
new direction of functional labeling involves conversion of transient expression from activity-dependent promoters into a permanent labeling based on tamoxifen-dependent recombinases
presence of the donor strain on the surface of the mutant selection plates, prevents the use of these plates for replica plating
In soil, bacteria tend to live in a state of dormancy due to prevailing oligotrophic conditions, which would not be particularly favorable for the development of competence
It can also be argued that the transformed DNA is a good resource of phosphates, nitrogen etc., so might be favoured in oligotrophic conditions?
bacteria generally express genes only when and where needed, and thus do not readily reveal their pathogenic armament outside of infected tissues
This gene fusion approach will allow us to assay the induction of gene expression in as few as one cell
Recombinase memory as a reporter for expression in 1 cell
causes of microbial ‘uncultivability’ are numerous
The stability of susceptibility patterns allowed the antibiograms to be used as aids in the preliminary differentiation of these organisms.
regulate gene expression, typically by occluding or exposing regulatory features, such as ribosome binding sites (RBSs) in the case of translation or intrinsic terminator hairpins in the case of transcription
improvement of soil health should be a priority agenda in India’s agricultural policy. We need steps to check wind and water erosion of soils. We need innovative technologies to minimise physical degradation of soils due to waterlogging, flooding and crusting. We need to improve the fertility of saline, acidic, alkaline and toxic soils by reclaiming them
Indian soils are poor in organic matter content. About 59% of soils are low in available nitrogen; about 49% are low in available phosphorus; and about 48% are low or medium in available potassium. Indian soils are also varyingly deficient in micronutrients, such as zinc, iron, manganese, copper, molybdenum and boron
In culture conditions that enhance cell-to-cell contact, conjugation rates approach 100% with the cis-acting plasmid
high efficiency
wastewater treatment plants are hotspots for the release of antibiotics, and transmission of diverse antibiotic resistance bacteria (ARB) as well as ARGs into various environments
That's a strong claim, not backed by strong evidence
Recent findings have indicated that most ARGs could not be efficiently removed by traditional anaerobic digestion treatment
Detection of AHL by LC-FTMS was much more sensitive than by TLC bioassay, because TLC bioassay was implied to be affected by the presence of quorum quenching molecules in activated sludge.
does not make sense
Biofilms grown under higher shear were more rigid and had a greater yield shear stress than those grown under lower shear.
Because growth conditions (i.e., fluid dynamics and nutrient composition) can also have a profound effect on when QS is important,(71-75) there is a need to study biofilm formation and QS of BNR bacteria under various potential operating conditions.
Many QS-controlled genes relate to biofilm formation and function and may be important for some water and wastewater treatment biofilms
it become possible to engineer these microbial structures to allow bacteria to form a stable granular sludge instead of flocculent sludge
The actual availability of NH4+ and NO3− is difficult to measure in soil. When rates of microbial N transformations and/or plant uptake are rapid, then NH4+ or NO3− levels can be undetectable in soil
it can be useful for reducing leaky expression of toxic proteins
antisense transcription
We report the construction of a family of vectors that contain a reengineered lacIq-lac promoter-operator complex in which cloned genes are strongly repressed in the absence of inducer.
difficult to observe in situ at the microscale, hence mechanisms and time scales relevant for bacterial spatial organization remain largely qualitative.
simulate the activated sludge process of a municipal waste water treatment plant and so better understand the fate of nanoplastics in urban environments
it has become a seemingly essential part of our life. It helps us to preserve food, keep warm, communicate with the world and much more
Frequency of QS among genome- sequenced bacteria
RP4 has been shown to exhibit a very broad host range and has been demonstrated to efficiently transfer in activated sludge (22, 40), chicken manure (24), and the rhizospheres of various plants (38, 39).
For in situ studies of AHL-dependent signaling in complex habitats, biosensors utilizing fluorescent proteins (GFP and RFP) as reporter genes have been developed
biosensors were employed to demonstrate AHL-mediated communication in swarm colonies of Serratia liquefaciens
they are induced in a way that correlates well with the AHL species produced by the strain
This is a baseless statement, made from only 1 strain p. aerofaciens, which makes C6-AHL
How does it correlate well then with 1 data point?
After 8 days of incubation, we detected cells that were only green fluorescent, indicating that the sensor plasmid had been transferred to indigenous AHL-producing organisms
It could also just mean that there are some AHL producers in the viscinity, just like the explanation given for yellow donor cells.
QS systems have been experimentally analyzed in more than 50 different bacterial species and shown to control expression of a wide spectrum of functions, including bioluminescence, virulence, symbiosis, different forms of motility, biofilm formation, production of antibiotics and toxins, and conjugation (49).
Over 20 orthogonal serine integrases have been characterized to date (6,11), and many now have identified RDFs.
it is unclear to what extent these results are relevant in natural habitats, as the standard assays neglect the different surface chemistries, interactions with other species, and physical constraints of natural environments.
Images were prepared for publication using CorelDraw (Corel Corporation) and PowerPoint (Microsoft) software.
Great that you cite the software
PpuI, which directs the biosynthesis of the two AHLs 3-oxo-C10 and 3-oxo-C12 as major products; PpuR, the AHL receptor; and RsaL a repressor of ppul
P. putida IsoF, isolated from tomato rhizosphere - quorum sensing
with pegs of polystyrene microtiter lid (catalog no. 445497; Nunc TSP system) immersed for bacterial biofilm formation
Planktonic stationary-phase cells were used in dose-response killing experiments, for a better comparison to biofilms
it may be possible to tag specific organisms and use these as monitor systems to estimate local chemical composition directly in the biofilms
placed at a 45° angle, nylon-mesh side up. Roots grew downward, collided with the bottom slide of the microcosm, and traveled along it. This method allowed observation of the root system by epifluorescence microscopy
well explained!
The rhizosphere is the volume of soil directly under the influence of plant roots; it is bounded by the root surface on one side and extends millimeters into the soil. It is populated with a high density of bacteria, fungi, protists, and nematodes supported by relatively labile organic compounds, such as sugars, amino acids, organic acids, and polysaccharides. These compounds are actively and passively lost from living and dying root tissues (12, 13). This rhizodeposition allows 5–100 times more organisms per unit volume to be supported in the rhizosphere than in nearby bulk soil, where the microbial community is thought to be carbon limited
This biosensor will help identify organic substrates that potentially support microbial growth and activity before and during nodulation
Such biosensors can reveal intriguing aspects of the environment and the physiology of the free-living soil S. meliloti before and during the establishment of nodulation, and they provide a nondestructive, spatially explicit method for examining rhizosphere soil chemical composition
Chemically, the differencebetween the DI water and the 0.25×M9 EPS solution aresome simple salts and just 14.5μg/ml glucose equivalent ofEPS
Should have compared with M9 + equivalent glucose (un-polymerized) as a better control for osmolarity reasons
if n is very small (for example n = 3), rather than showing error bars and statistics, it is better to simply plot the individual data points.
For n to be greater than 1, the experiment would have to be performed using separate stock cultures, or separate cell clones of the same type
quantifying biogeochemical fluxes resulting from these reactions remains a challenge
These tools provide insights into processes such as N uptake at the scale of individual root tips, allowing observation of plant–microbe interactions on scales at which they actually occur, instead of being masked by a whole‐core average
detection of methyl halides at femtomolar levels and quantification at concentrations above 10 pM
This is approximately 6 molecules per cell - seems too low. (assuming cell volume is 1 um^3 - for e coli) - https://bionumbers.hms.harvard.edu/bionumber.aspx?id=100004&ver=20&trm=100004&org=
The following might be a pretty cumbersome workaround for tiled clones with spacing e.g. in millimeters instead of %.
A narrative weaves together otherwise isolated bits of information into a meaningful whole, linking them in important ways but also chunking the information so that it takes up less space in working memory and connects to existing threads in long-term memory
students quite often reported choosing their major based on taking introductory courses with particularly dynamic professors.
your enthusiasm as an instructor is indeed contagious and helps predict variables like student motivation in the course.
make the entire course relevant to students’ daily lives. All of the labs center around chemicals and materials that students interact with regularly. For instance, they evaluate bottled water versus tap water, test both for pH, conductivity, and taste, and then debate why so many people choose bottled over tap
You can also make class activities relevant to contemporary social movements, to future careers in your major, or to some transcendent purpose
Jennifer Gonzalez, editor of the teaching blog Cult of Pedagogy, summed up the concept quite nicely in the title of a blog post: “To Learn, Students Need to DO Something.”
essential goal for me in every course has always been to make students feel comfortable participating in class, and to encourage as many of them as possible to speak up. Peer instruction, aided by electronic polling, gave me an opportunity to invite quiet students to engage more actively in class, both through the polls and through the subsequent discussions
When new knowledge is integrated with and connected to existing knowledge, that new knowledge is easier to understand and to remember. A professor’s job is to build scaffolding from existing knowledge on which to hang incoming new knowledge. Using a concept map is one way to build that scaffolding.
exogenous addition of AHLs to sludge resulted in long-lasting impacts on phenol degradation
text files? Gloriously simple, ready made for your favorite text editor and perfect for version control.
Latex files can do version control vs word files
R markdown has the possibility of executing R code inline (and rendering the result to html) or rendering graphs inline. That saves time and makes the documentation maintainable as you don't need to manually prepare the output of that function or manually prepare and save a graph since it's rendered on the fly.
R markdown makes documentation of code easy
more convenient and effective methods is required for qualitative and quantitative analysis of AHLs
enzymatic quenching mechanism of AHL signals is also present in enzyme-producing bacteria, such as Anabaena sp. PCC7120, Ralstonia sp. XJ12B, P. aeruginosa PAO1, Agrobacterium tumefaciens C58, Bacillus sp. strain 240B1, Rhodococcus erythropolis strain W2
Membrane biofouling remains to be one of the most serious operational problems for MBR applications, which results in permeate flux and water quality decline, trans-membrane pressure (TMP) and operating costs increase, frequent membrane cleaning and replacement necessary
activated sludge flocs are complicated aggregates containing inorganic and organic particles as well as a high-density microbial consortium embedded in a matrix of extracellular polymeric substances
Coordinated behaviours include bioluminescence3,4, virulence factor production5,6, secondary metabolite production7, competence for DNA uptake8,9 and biofilm formation10,11.
We focus on how quorums are detected and how quorum sensing controls group behaviours in complex and dynamically changing environments such as multi-species bacterial communities, in the presence of flow, in 3D non-uniform biofilms and in hosts during infection.
Laboratory strains of Escherichia coli do not show significant ability to attach to solid surfaces and to form biofilms
stabilization of microbial community
AHL was found to play important roles in wastewater treatment processes, in particular, formation of aerobic sludge granules
bacterial QQ does not completely prevent biofouling; it simply postpones its occurrence
it has been assumed that the effectiveness of Pseudomonas sp. 1A1 in mitigating membrane biofouling could be expected to be more significant, given that the QQ enzyme that it produces (acylase) is extracellular
The acylase might not be functional or stable in the extracellular wastewater environment
Design of the LOCKR system.
It would be amazing if you could fit the rate constants from experimental data
different fouling patterns were observed for replicate MBRs seeded with the same inoculum and maintained under identical operating conditions, with similar levels of biomass, soluble microbial products, and extracellular polymeric substances
The reactors were not maintained under the same conditions - 1 had backpulsing and the other was subjected to relaxation
achieved only a 10% increase of permeate flux when backpulsing was used in the filtration of a biological wastewater containing a high mixed liquor suspended solids
Figure 5
Why did the QQ-MBR go down on day 20?
Figure 2. TMP profiles during the operation of two one-stage MBRs in two phases.
Fouling seems to happen exponentially once it starts => following a first order reaction. What is the mechanism behind this?
C8-HSL was chosen as a representative AHL molecule because it is one of the dominant AHL molecules in MBRs for wastewater treatment
a critical issue in MBR that awaits a technological advancement to solve is membrane biofouling, which leads to high energy consumption and thus high operating costs
TMP-Jump
Why does TMP jump so rapidly?
Plasmids (IncP/N/W)with 373short and rigid pili only transfer efficiently on solid surfaces, unlike those with longand flexible 374pili (IncF/H/T/J),capable of transferring equally well in liquidand on solid surfaces[35,36]
Plasmid group vs pili length
identify mechanistic drivers of microbial activity, infer meaningful interaction networks, and rationally engineer microbial communities.
Mechanistic insights in microbial ecology
Next, a microfluidic device is used to co-encapsulate these clusters with gel beads, each containing uniquely barcoded forward 16S rRNA amplification primers
Isn't the spatial information lost while encapsulation? Is the barcode capturing the spatial information in some way? It is not clear
current microbiome profiling approaches such as metagenomic sequencing require homogenization of input material, which means that underlying spatial information is lost
recording past events, to study localization of single-cell transcriptional events within the gut
These carboxylated AHLs facilitated the transition from a short cell to filamentous growth, with an altered carbon metabolic flux that favoured the conversion of acetate to methane and a reduced yield in cellular biomass
Carboxylated AHL signalling favours methanogenesis in Methanosaeta herundinacea 6Ac
Deletion of genes thatproduceN-acyl-L-homoserine lactone signals resulted in an increase in denitrification activity, which wasrepressed by exogenous signal molecules.
AHL is lowering denitrification in Psuedomonas aeruginosa
The prokaryotic CRISPR-Cas system of defense against mobile elements seems to function via a bona fide Lamarckian mechanism
scientists are uncovering and debating an increasing array of other evolutionary processes at work in bacteria, some of which are suspiciously Lamarckian in character4–6
Instead, most particle-attached bacteria may be secondary consumers that recycle waste products from primary degraders.
What factors determine their relative abundance then?
co-occur out of cooperative relations or a similar niche preference
similar niche evokes competition rather than cooperation, this is contradictory
beneficial commensal
mutualist?
antibodies against siderophores in the intestine, which hindered proliferation of the gut pathogen Salmonella
What about normal gut microbiota? I presume they need iron too
At the micrometer-centimeter scale, electrochemical and optical probes have been productively used to profile gradients in pH, redox, and oxygen; however, these probes and their associated equipment are intrusive to the ecosystem and often expensive, limiting their application to only a few point measurements or limited time series, and their fragile nature makes them best suited for laboratory use
CustoMem in the UK uses synthetic biology to create a granular material that attracts and sticks to micropollutants such as pesticides, pharmaceuticals, and certain chemicals in wastewater
MicroBio Engineering Inc., a research and engineering consulting firm specializing in developing improved algal strains and cultivation processes for wastewater reclamation, animal feeds, higher value products and, yes, biofuels.
In Japan, scientists are developing synthetically altered soy plants and yeast that produce glycyrrhizen, a compound in licorice root that is 150 to 300 times sweeter than sugar