scholarly journals Unravelling the genetic basis for competence development of auxotrophic Bacillus licheniformis 9945A strains

Microbiology ◽  
2014 ◽  
Vol 160 (10) ◽  
pp. 2136-2147 ◽  
Author(s):  
Mareike Jakobs ◽  
Kerstin Hoffmann ◽  
Anja Grabke ◽  
Stefania Neuber ◽  
Heiko Liesegang ◽  
...  
Keyword(s):  
Bacillus Licheniformis ◽  
Extracellular Enzymes ◽  
Random Mutagenesis ◽  
Extracellular Enzyme ◽  
Competence Development ◽  
Colony Morphology ◽  
Enzyme Secretion ◽  
Dna Uptake ◽  
Genetic Competence ◽  
Regulator Genes

Bacterial natural genetic competence – well studied in Bacillus subtilis – enables cells to take up and integrate extracellularly supplied DNA into their own genome. However, little is known about competence development and its regulation in other members of the genus, although DNA uptake machineries are routinely encoded. Auxotrophic Bacillus licheniformis 9945A derivatives, obtained from repeated rounds of random mutagenesis, were long known to develop natural competence. Inspection of the colony morphology and extracellular enzyme secretion of two of these derivatives, M28 and M18, suggested that regulator genes are collaterally hit. M28 emerged as a 14 bp deletion mutant concomitantly displaying a shift in the reading frame of degS that encodes the sensor histidine kinase, which is part of the molecular switch that directs cells to genetic competence, the synthesis of extracellular enzymes or biofilm formation, while for M18, sequencing of the suspected gene revealed a 375 bp deletion in abrB, encoding the major transition state regulator. With respect to colony morphology, enzyme secretion and competence development, both of the mutations, when newly generated on the wild-type B. licheniformis 9945A genetic background, resulted in phenotypes resembling M28 and M18, respectively. All of the known naturally competent B. licheniformis representatives, hitherto thoroughly investigated in this regard, carry mutations in regulator genes, and hence genetic competence observed in domesticated strains supposedly results from deregulation.

scholarly journals The YtrBCDEF ABC transporter is involved in the control of social activities in Bacillus subtilis

2020 ◽  
Author(s):  
Martin Benda ◽  
Lisa Schulz ◽  
Jeanine Rismondo ◽  
Jörg Stülke
Keyword(s):  
Cell Wall ◽  
Transcription Factor ◽  
Bacillus Subtilis ◽  
Abc Transporter ◽  
Biofilm Formation ◽  
Translational Regulation ◽  
Constitutive Expression ◽  
Competence Development ◽  
Dna Uptake ◽  
Genetic Competence

AbstractBacillus subtilis develops genetic competence for the uptake of foreign DNA when cells enter the stationary phase and a high cell density is reached. These signals are integrated by the competence transcription factor ComK which is subject to transcriptional, post-transcriptional and post-translational regulation. Many proteins are involved in the development of competence, both to control ComK activity and to mediate DNA uptake. However, the precise function they play in competence development is often unknown. In this study, we have tested whether proteins required for genetic transformation play a role in the activation of ComK or rather downstream of competence gene expression. While these possibilities could be distinguished for most of the tested factors, two proteins (PNPase and the transcription factor YtrA) are required both for full ComK activity and for the downstream processes of DNA uptake and integration. Further analyses of the role of the transcription factor YtrA for the competence development revealed that the constitutive expression of the YtrBCDEF ABC transporter in the ytrA mutant causes the loss of genetic competence. Moreover, constitutive expression of this ABC transporter also interferes with biofilm formation. Since the ytrGABCDEF operon is induced by cell wall-targeting antibiotics, we tested the cell wall properties upon overexpression of the ABC transporter and observed an increased thickness of the cell wall. The composition and properties of the cell wall are important for competence development and biofilm formation, suggesting that the increased cell wall thickness as a result of YtrBCDEF overexpression causes the observed phenotypes.

scholarly journals Optimality of extracellular enzyme production and activity in dynamic flux balance modeling

2021 ◽  
Author(s):  
Michael Quintin ◽  
Ilija Dukovski ◽  
Jennifer Bhatnagar ◽  
Daniel Segrè
Keyword(s):  
Enzyme Production ◽  
Metabolic Networks ◽  
Community Dynamics ◽  
Extracellular Enzymes ◽  
Extracellular Enzyme ◽  
Enzyme Secretion ◽  
Kinetic Properties ◽  
Dynamic Flux Balance Analysis ◽  
Flux Balance ◽  
Microbial Community Dynamics

In microbial communities, many vital metabolic functions, including the degradation of cellulose, proteins and other complex macromolecules, are carried out by costly, extracellularly secreted enzymes. While significant effort has been dedicated to analyzing genome-scale metabolic networks for individual microbes and communities, little is known about the interplay between global allocation of metabolic resources in the cell and extracellular enzyme secretion and activity. Here we introduce a method for modeling the secretion and catalytic functions of extracellular enzymes using dynamic flux balance analysis. This new addition, implemented within COMETS (Computation Of Microbial Ecosystems in Time and Space), simulates the costly production and secretion of enzymes and their diffusion and activity throughout the environment, independent of the producing organism. After tuning our model based on data for a Saccharomyces cerevisiae strain engineered to produce exogenous cellulases, we explored the dynamics of the system at different cellulose concentrations and enzyme production rates. We found that there are distinct rates of constitutive enzyme secretion which maximize either growth rate or biomass yield. These optimal rates are strongly dependent on enzyme kinetic properties and environmental conditions, including the amount of cellulose substrate available. Our framework will facilitate the development of more realistic simulations of microbial community dynamics within environments rich in complex macromolecules, with applications in the study of soil and plant-associated ecosystems, and other natural and engineered microbiomes.

scholarly journals Influence of the ABC Transporter YtrBCDEF of Bacillus subtilis on Competence, Biofilm Formation and Cell Wall Thickness

2021 ◽  
Vol 12 ◽  
Author(s):  
Martin Benda ◽  
Lisa Maria Schulz ◽  
Jörg Stülke ◽  
Jeanine Rismondo
Keyword(s):  
Cell Wall ◽  
Transcription Factor ◽  
Bacillus Subtilis ◽  
Abc Transporter ◽  
Wall Thickness ◽  
Biofilm Formation ◽  
Competence Development ◽  
Cell Wall Thickness ◽  
Dna Uptake ◽  
Genetic Competence

Bacillus subtilis develops genetic competence for the uptake of foreign DNA when cells enter stationary phase and a high cell density is reached. These signals are integrated by the competence transcription factor ComK, which is subject to transcriptional, post-transcriptional and post-translational regulation. Many proteins are involved in the development of competence, both to control ComK activity and to mediate DNA uptake. However, for many proteins, the precise function they play in competence development is unknown. In this study, we assessed whether proteins required for genetic transformation play a role in the activation of ComK or rather act downstream of competence gene expression. While these possibilities could be distinguished for most of the tested factors, we assume that two proteins, PNPase and the transcription factor YtrA, are required both for full ComK activity and for the downstream processes of DNA uptake and integration. Further analyses of the role of the transcription factor YtrA for the competence development revealed that the overexpression of the YtrBCDEF ABC transporter in the ytrA mutant causes the loss of genetic competence. Moreover, overexpression of this ABC transporter also affects biofilm formation. Since the ytrGABCDEF operon is naturally induced by cell wall-targeting antibiotics, we tested the cell wall properties upon overexpression of the ABC transporter and observed an increased thickness of the cell wall. The composition and properties of the cell wall are important for competence development and biofilm formation, suggesting that the observed phenotypes are the result of the increased cell wall thickness as an outcome of YtrBCDEF overexpression.

scholarly journals Extracellular hydrolytic enzyme production by proteolytic bacteria from the Antarctic

2013 ◽  
Vol 34 (3) ◽  
pp. 253-267 ◽  
Author(s):  
Mauro Tropeano ◽  
Susana Vázquez ◽  
Silvia Coria ◽  
Adrián Turjanski ◽  
Daniel Cicero ◽  
...  
Keyword(s):  
Extracellular Enzymes ◽  
Restriction Analysis ◽  
Hydrolytic Enzyme ◽  
Hydrolytic Enzymes ◽  
Extracellular Enzyme ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Potter Cove ◽  
Starting Point ◽  
Dna Restriction

AbstractCold−adapted marine bacteria producing extracellular hydrolytic enzymes are important for their industrial application and play a key role in degradation of particulate organic matter in their natural environment. In this work, members of a previously−obtained protease−producing bacterial collection isolated from different marine sources from Potter Cove (King George Island, South Shetlands) were taxonomically identified and screened for their ability to produce other economically relevant enzymes. Eighty−eight proteolytic bacterial isolates were grouped into 25 phylotypes based on their Amplified Ribosomal DNA Restriction Analysis profiles. The sequencing of the 16S rRNA genes from representative isolates of the phylotypes showed that the predominant culturable protease−producing bacteria belonged to the class Gammaproteobacteria and were affiliated to the genera Pseudomonas, Shewanella, Colwellia, and Pseudoalteromonas, the latter being the predominant group (64% of isolates). In addition, members of the classes Actinobacteria, Bacilli and Flavobacteria were found. Among the 88 isolates screened we detected producers of amylases (21), pectinases (67), cellulases (53), CM−cellulases (68), xylanases (55) and agarases (57). More than 85% of the isolates showed at least one of the extracellular enzymatic activities tested, with some of them producing up to six extracellular enzymes. Our results confirmed that using selective conditions to isolate producers of one extracellular enzyme activity increases the probability of recovering bacteria that will also produce additional extracellular enzymes. This finding establishes a starting point for future programs oriented to the prospecting for biomolecules in Antarctica.

The two putative comS homologs of the biotechnologically important Bacillus licheniformis do not contribute to competence development

2014 ◽  
Vol 99 (5) ◽  
pp. 2255-2266 ◽  
Author(s):  
Mareike Jakobs ◽  
Kerstin Hoffmann ◽  
Heiko Liesegang ◽  
Sonja Volland ◽  
Friedhelm Meinhardt
Keyword(s):  
Bacillus Licheniformis ◽  
Competence Development

scholarly journals Response of <i>Nodularia spumigena</i> to <i>p</i>CO<sub>2</sub> – Part 2: Exudation and extracellular enzyme activities

2013 ◽  
Vol 10 (1) ◽  
pp. 567-582 ◽  
Author(s):  
S. Endres ◽  
J. Unger ◽  
N. Wannicke ◽  
M. Nausch ◽  
M. Voss ◽  
...  
Keyword(s):  
Alkaline Phosphatase ◽  
Organic Matter ◽  
Enzyme Activities ◽  
Extracellular Enzymes ◽  
Extracellular Enzyme ◽  
High Pco2 ◽  
Nodularia Spumigena ◽  
Extracellular Enzyme Activities ◽  
Pco2 Treatment ◽  
Co2 Concentrations

Abstract. The filamentous and diazotrophic cyanobacterium Nodularia spumigena plays a major role in the productivity of the Baltic Sea as it forms extensive blooms regularly. Under phosphorus limiting conditions Nodularia spumigena have a high enzyme affinity for dissolved organic phosphorus (DOP) by production and release of alkaline phosphatase. Additionally, they are able to degrade proteinaceous compounds by expressing the extracellular enzyme leucine aminopeptidase. As atmospheric CO2 concentrations are increasing, we expect marine phytoplankton to experience changes in several environmental parameters, including pH, temperature, and nutrient availability. The aim of this study was to investigate the combined effect of CO2-induced changes in seawater carbonate chemistry and of phosphate deficiency on the exudation of organic matter, and its subsequent recycling by extracellular enzymes in a Nodularia spumigena culture. Batch cultures of Nodularia spumigena were grown for 15 days under aeration with low (180 μatm), medium (380 μatm), and high (780 μatm) CO2 concentrations. Obtained pCO2 levels in the treatments were on median 315, 353, and 548 μatm CO2, respectively. Extracellular enzyme activities as well as changes in organic and inorganic compound concentrations were monitored. CO2 treatment–related effects were identified for cyanobacterial growth, which in turn influenced the concentration of mucinous substances and the recycling of organic matter by extracellular enzymes. Biomass production was increased by 56.5% and 90.7% in the medium and high pCO2 treatment, respectively, compared to the low pCO2 treatment. In total, significantly more mucinous substances accumulated in the high pCO2 treatment, reaching 363 μg Xeq L−1 compared to 269 μg Xeq L−1 in the low pCO2 treatment. However, cell-specific rates did not change. After phosphate depletion, the acquisition of P from DOP by alkaline phosphatase was significantly enhanced. Alkaline phosphatase activities were increased by factor 1.64 and 2.25, respectively, in the medium and high compared to the low pCO2 treatment. We hypothesise from our results that Nodularia spumigena can grow faster under elevated pCO2 by enhancing the recycling of organic matter to acquire nutrients.

scholarly journals Extracellular Enzyme Secretion by Pseudomonas lemoignei

1974 ◽  
Vol 119 (1) ◽  
pp. 152-161 ◽  
Author(s):  
M. W. Stinson ◽  
J. M. Merrick
Keyword(s):  
Extracellular Enzyme ◽  
Enzyme Secretion

Temperature Sensitivity of Intracellular and Extracellular Soil Enzyme Activities

2021 ◽  
Author(s):  
Adetunji Alex Adekanmbi ◽  
Laurence Dale ◽  
Liz Shaw ◽  
Tom Sizmur
Keyword(s):  
Enzyme Activity ◽  
Soil Temperature ◽  
Temperature Sensitivity ◽  
Extracellular Enzymes ◽  
Extracellular Enzyme ◽  
Daily Maximum ◽  
Temperature Sensitive ◽  
Intracellular Enzyme ◽  
Temperature Changes ◽  
Som Decomposition

&lt;p&gt;Predicting the pattern of soil organic matter (SOM) decomposition as a feedback to climate change, via release of CO&lt;sub&gt;2&lt;/sub&gt;, is extremely complex and has received much attention. However, investigations often do not differentiate between the extracellular and intracellular processes involved and work is needed to identify their relative temperature sensitivities. Samples were collected from a grassland soil at Sonning, UK with average daily maximum and minimum soil temperature of 15 &amp;#176;C and 5 &amp;#176;C. We measured potential activities of &amp;#946;-glucosidase (BG) and chitinase (NAG) (extracellular enzymes) and glucose-induced CO&lt;sub&gt;2 &lt;/sub&gt;respiration (intracellular enzymes) at a range of assay temperatures (5 &amp;#176;C, 15 &amp;#176;C, 26 &amp;#176;C, 37&lt;sup&gt; &amp;#160;&lt;/sup&gt;&amp;#176;C, and 45 &amp;#176;C). The temperature coefficient Q&lt;sub&gt;10&lt;/sub&gt; (the increase in enzyme activity that occurs after a 10 &amp;#176;C increase in soil temperature) was calculated to assess the temperature sensitivity of intracellular and extracellular enzymes activities. Between 5 &amp;#176;C and 15 &amp;#176;C intracellular and extracellular enzyme activities had equal temperature sensitivity, but between 15 &amp;#176;C and 26&amp;#176;C intracellular enzyme activity was more temperature sensitive than extracellular enzyme activity and between 26 &amp;#176;C and 37 &amp;#176;C extracellular enzyme activity was more temperature sensitive than intracellular enzyme activity. This result implies that extracellular depolymerisation of higher molecular weight organic compounds is more sensitive to temperature changes at higher temperatures (e.g. changes to daily maximum summer temperature) but the intracellular respiration of the generated monomers is more sensitive to temperature changes at moderate temperatures (e.g. changes to daily mean summer temperature). We therefore conclude that the extracellular and intracellular steps of SOM mineralisation are not equally sensitive to changes in soil temperature. The finding is important because we have observed greater increases in average daily minimum temperatures than average daily mean or maximum temperatures due to increased cloud cover and sulphate aerosol emission. Accounting for this asymmetrical global warming may reduce the importance of extracellular depolymerisation and increase the importance of intracellular catalytic activities as the rate limiting step of SOM decomposition.&lt;/p&gt;

scholarly journals Patterns and Drivers of Extracellular Enzyme Activity in New Zealand Glacier-Fed Streams

2020 ◽  
Vol 11 ◽  
Author(s):  
Tyler J. Kohler ◽  
Hannes Peter ◽  
Stilianos Fodelianakis ◽  
Paraskevi Pramateftaki ◽  
Michail Styllas ◽  
...  
Keyword(s):  
Climate Change ◽  
Extracellular Polymeric Substances ◽  
Extracellular Enzymes ◽  
Inorganic Nitrogen ◽  
Extracellular Enzyme ◽  
Microbial Life ◽  
Mountain Glaciers ◽  
P Limitation ◽  
Habitat Template ◽  
N Demand

Glacier-fed streams (GFSs) exhibit near-freezing temperatures, variable flows, and often high turbidities. Currently, the rapid shrinkage of mountain glaciers is altering the delivery of meltwater, solutes, and particulate matter to GFSs, with unknown consequences for their ecology. Benthic biofilms dominate microbial life in GFSs, and play a major role in their biogeochemical cycling. Mineralization is likely an important process for microbes to meet elemental budgets in these systems due to commonly oligotrophic conditions, and extracellular enzymes retained within the biofilm enable the degradation of organic matter and acquisition of carbon (C), nitrogen (N), and phosphorus (P). The measurement and comparison of these extracellular enzyme activities (EEA) can in turn provide insight into microbial elemental acquisition effort relative to environmental availability. To better understand how benthic biofilm communities meet resource demands, and how this might shift as glaciers vanish under climate change, we investigated biofilm EEA in 20 GFSs varying in glacier influence from New Zealand’s Southern Alps. Using turbidity and distance to the glacier snout normalized for glacier size as proxies for glacier influence, we found that bacterial abundance (BA), chlorophyll a (Chl a), extracellular polymeric substances (EPS), and total EEA per gram of sediment increased with decreasing glacier influence. Yet, when normalized by BA, EPS decreased with decreasing glacier influence, Chl a still increased, and there was no relationship with total EEA. Based on EEA ratios, we found that the majority of GFS microbial communities were N-limited, with a few streams of different underlying bedrock geology exhibiting P-limitation. Cell-specific C-acquiring EEA was positively related to the ratio of Chl a to BA, presumably reflecting the utilization of algal exudates. Meanwhile, cell-specific N-acquiring EEA were positively correlated with the concentration of dissolved inorganic nitrogen (DIN), and both N- and P-acquiring EEA increased with greater cell-specific EPS. Overall, our results reveal greater glacier influence to be negatively related to GFS biofilm biomass parameters, and generally associated with greater microbial N demand. These results help to illuminate the ecology of GFS biofilms, along with their biogeochemical response to a shifting habitat template with ongoing climate change.

scholarly journals A Model of Extracellular Enzymes in Free-Living Microbes: Which Strategy Pays Off?

2015 ◽  
Vol 81 (21) ◽  
pp. 7385-7393 ◽  
Author(s):  
Sachia J. Traving ◽  
Uffe H. Thygesen ◽  
Lasse Riemann ◽  
Colin A. Stedmon
Keyword(s):  
Extracellular Enzymes ◽  
Extracellular Enzyme ◽  
Threshold Concentration ◽  
Free Living ◽  
Deployment Strategy ◽  
Solitary Cell ◽  
Low Concentrations ◽  
Refractory State ◽  
Ocean Carbon ◽  
Cost Efficient

ABSTRACTAn initial modeling approach was applied to analyze how a single, nonmotile, free-living, heterotrophic bacterial cell may optimize the deployment of its extracellular enzymes. Free-living cells live in a dilute and complex substrate field, and to gain enough substrate, their extracellular enzymes must be utilized efficiently. The model revealed that surface-attached and free enzymes generate unique enzyme and substrate fields, and each deployment strategy has distinctive advantages. For a solitary cell, surface-attached enzymes are suggested to be the most cost-efficient strategy. This strategy entails potential substrates being reduced to very low concentrations. Free enzymes, on the other hand, generate a radically different substrate field, which suggests significant benefits for the strategy if free cells engage in social foraging or experience high substrate concentrations. Swimming has a slight positive effect for the attached-enzyme strategy, while the effect is negative for the free-enzyme strategy. The results of this study suggest that specific dissolved organic compounds in the ocean likely persist below a threshold concentration impervious to biological utilization. This could help explain the persistence and apparent refractory state of oceanic dissolved organic matter (DOM). Microbial extracellular enzyme strategies, therefore, have important implications for larger-scale processes, such as shaping the role of DOM in ocean carbon sequestration.

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