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FEMS Microbiology Reviews Jan 2022Because the majority of bacterial species divide by binary fission, and do not have distinguishable somatic and germline cells, they could be considered to be immortal.... (Review)
Review
Because the majority of bacterial species divide by binary fission, and do not have distinguishable somatic and germline cells, they could be considered to be immortal. However, bacteria 'age' due to damage to vital cell components such as DNA and proteins. DNA damage can often be repaired using efficient DNA repair mechanisms. However, many proteins have a functional 'shelf life'; some are short lived, while others are relatively stable. Specific degradation processes are built into the life span of proteins whose activities are required to fulfil a specific function during a prescribed period of time (e.g. cell cycle, differentiation process, stress response). In addition, proteins that are irreparably damaged or that have come to the end of their functional life span need to be removed by quality control proteases. Other proteases are involved in performing a variety of specific functions that can be broadly divided into three categories: processing, regulation and feeding. This review presents a systematic account of the proteases of Bacillus subtilis and their activities. It reviews the proteases found in, or associated with, the cytoplasm, the cell membrane, the cell wall and the external milieu. Where known, the impacts of the deletion of particular proteases are discussed, particularly in relation to industrial applications.
Topics: Bacillus; Bacillus subtilis; Bacterial Proteins; Cell Division; Peptide Hydrolases
PubMed: 34410368
DOI: 10.1093/femsre/fuab046 -
Journal of Bacteriology Nov 2022Bacillus anthracis, Bacillus cereus, and Bacillus thuringiensis are the major pathogens of the spore-forming genus and possess an outer spore layer, the exosporium, not...
Bacillus anthracis, Bacillus cereus, and Bacillus thuringiensis are the major pathogens of the spore-forming genus and possess an outer spore layer, the exosporium, not found in many of the nonpathogenic species. The exosporium consists of a basal layer with the ExsY, CotY, and BxpB proteins being the major structural components and an exterior nap layer containing the BclA glycoprotein. During the assembly process, the nascent exosporium basal layer is attached to the spore coat by a protein linker that includes the CotO and CotE proteins. Using transmission electron microscopy, Western blotting, immunofluorescence, and fluorescent fusion protein approaches, we examined the impact of single, double, and triple mutants of the major exosporium proteins on exosporium protein content and distribution. Plasmid-based expression of and resulted in increased production of exosporium lacking spores, and the former also resulted in outer spore coat disruptions. The exosporium bottlecap produced by null spores was found to be more stable than previously reported, and its spore association was partially dependent on CotE. Deletion mutants of five putative spore genes (, , , , and ) were created and shown not to have obvious effects on spore morphology or BclA and BxpB content. The BclC collagen-like glycoprotein was found to be present in the spore and possibly localized to the interspace region. B. anthracis is an important zoonotic animal pathogen causing sporadic outbreaks of anthrax worldwide. Spores are the infectious form of the bacterium and can persist in soil for prolonged periods of time. The outermost B. anthracis spore layer is the exosporium, a protein shell that is the site of interactions with both the soil and with the innate immune system of infected hosts. Although much is known regarding the sporulation process among members of the genus , significant gaps in our understanding of the exosporium assembly process exist. This study provides evidence for the properties of key exosporium basal layer structural proteins. The results of this work will guide future studies on exosporium protein-protein interactions during the assembly process.
Topics: Bacillus anthracis; Spores, Bacterial; Bacterial Proteins; Membrane Glycoproteins; Bacillus; Glycoproteins; Soil
PubMed: 36194010
DOI: 10.1128/jb.00291-22 -
Microbiology (Reading, England) Aug 2021The crisis of antimicrobial resistant bacterial infections is one of the most pressing public health issues. Common agricultural practices have been implicated in the...
The crisis of antimicrobial resistant bacterial infections is one of the most pressing public health issues. Common agricultural practices have been implicated in the generation of antimicrobial resistant bacteria. Biopesticides, live bacteria used for pest control, are non-pathogenic and considered safe for consumption. Application of bacteria-based pesticides to crops in high concentrations raises the possibility of unintentional contributions to the movement and generation of antimicrobial resistance genes in the environment. However, the presence of clinically relevant antimicrobial resistance genes and their resistance phenotypes are currently unknown. Here we use a combination of multiple bioinformatic and microbiological techniques to define resistomes of widely used biopesticides and determine how the presence of suspected antimicrobial resistance genes translates to observable resistance phenotypes in several biopesticide products. Our results demonstrate that biopesticide products are reservoirs of clinically relevant antimicrobial resistance genes and bear resistance to multiple drug classes.
Topics: Anti-Bacterial Agents; Bacillus; Biological Control Agents; Crops, Agricultural; Drug Resistance, Bacterial
PubMed: 34351257
DOI: 10.1099/mic.0.001074 -
Applied and Environmental Microbiology Mar 2020Changes with time of a population of KBAB4 and AD978 dormant spores into germinated spores and vegetative cells were followed by flow cytometry, at pH ranges of 4.7 to...
Changes with time of a population of KBAB4 and AD978 dormant spores into germinated spores and vegetative cells were followed by flow cytometry, at pH ranges of 4.7 to 7.4 and temperatures of 10°C to 37°C for and 18°C to 59°C for Incubation conditions lower than optimal temperatures or pH led to lower proportions of dormant spores able to germinate and extended time of germination, a lower proportion of germinated spores able to outgrow, an extension of their times of outgrowth, and an increase of the heterogeneity of spore outgrowth time. A model based on the strain growth limits was proposed to quantify the impact of incubation temperature and pH on the passage through each physiological stage. The heat treatment temperature or time acted independently on spore recovery. Indeed, a treatment at 85°C for 12 min or at 95°C for 2 min did not have the same impact on spore germination and outgrowth kinetics of despite the fact that they both led to a 10-fold reduction of the population. Moreover, acidic sporulation pH increased the time of outgrowth 1.2-fold and lowered the proportion of spores able to germinate and outgrow 1.4-fold. Interestingly, we showed by proteomic analysis that some proteins involved in germination and outgrowth were detected at a lower abundance in spores produced at pH 5.5 than in those produced at pH 7.0, maybe at the origin of germination and outgrowth behavior of spores produced at suboptimal pH. Sporulation and incubation conditions have an impact on the numbers of spores able to recover after exposure to sublethal heat treatment. Using flow cytometry, we were able to follow at a single-cell level the changes in the physiological states of heat-stressed spores of spp. and to discriminate between dormant spores, germinated spores, and outgrowing vegetative cells. We developed original mathematical models that describe (i) the changes with time of the proportion of cells in their different states during germination and outgrowth and (ii) the influence of temperature and pH on the kinetics of spore recovery using the growth limits of the tested strains as model parameters. We think that these models better predict spore recovery after a sublethal heat treatment, a common situation in food processing and a concern for food preservation and safety.
Topics: Bacillus; Bacillus licheniformis; Hot Temperature; Models, Theoretical; Spores, Bacterial
PubMed: 31900309
DOI: 10.1128/AEM.02061-19 -
The Science of the Total Environment Nov 2022Mangroves are located at the interface of terrestrial and marine environments, and experience fluctuating conditions, creating a need to better explore the relative role...
Mangroves are located at the interface of terrestrial and marine environments, and experience fluctuating conditions, creating a need to better explore the relative role of the bacterial community. Bacillus has been reported to be the dominant group in the mangrove ecosystem and plays a key role in maintaining the biodiversity and function of the mangrove ecosystem. However, studies on bacterial and Bacillus community across four seasons in the mangrove ecosystem are scarce. Here, we employed seasonal large-scale sediment samples collected from the mangrove ecosystem in southeastern China and utilized 16S rRNA gene amplicon sequencing to reveal bacterial and Bacillus community structure changes across seasons. Compared with the whole bacterial community, we found that Bacillus community was greatly affected by season (temperature) rather than site. The key factors, NO-N and NH-N showed opposite interaction with superabundant taxa Bacillus taxa (SAT) and three rare Bacillus taxa including high rare taxa (HRT), moderate rare taxa (MRT) and low rare taxa (LRT). Network analysis suggested the co-occurrence of Bacillus community and Bacillus-bacteria, and revealed SAT had closer relationship compared with rare Bacillus taxa. HRT might act crucial response during the temperature decreasing process across seasons. This study fills a gap in addressing the assembly of Bacillus community and their role in maintaining microbial diversity and function in mangrove ecosystem.
Topics: Bacillus; Bacteria; Biodiversity; China; Ecosystem; RNA, Ribosomal, 16S; Temperature
PubMed: 35870580
DOI: 10.1016/j.scitotenv.2022.157496 -
Biotechnology Advances Nov 2022Microbial biosurfactants have attracted the attention of researchers and companies for the last decades, as they are considered promising candidates to replace chemical... (Review)
Review
Microbial biosurfactants have attracted the attention of researchers and companies for the last decades, as they are considered promising candidates to replace chemical surfactants in numerous applications. Although in the last years, considerable advances were performed regarding strain engineering and the use of low-cost substrates in order to reduce their production costs, one of the main bottlenecks is their production at industrial scale. Conventional aerobic biosurfactant production processes result in excessive foaming, due to the use of high agitation and aeration rates necessary to increase dissolved oxygen concentration to allow microbial growth and biosurfactant production. Different approaches have been studied to overcome this problem, although with limited success. A not widely explored alternative is the development of foam-free processes through the anaerobic growth of biosurfactant-producing microorganisms. Surfactin, produced by Bacillus subtilis, is the most widely studied lipopeptide biosurfactant, and the most powerful biosurfactant known so far. Bacillus licheniformis strains produce lichenysin, a lipopeptide biosurfactant which structure is similar to surfactin. However, despite its extraordinary surface-active properties and potential applications, lichenysin has been scarcely studied. According to previous studies, B. licheniformis is better adapted to anaerobic growth than B. subtilis, and could be a good alternative for the anaerobic production of lipopeptide biosurfactants. In this review, the potential and limitations of surfactin and lichenysin production under anaerobic conditions will be analyzed, and the possibility of implementing foam-free processes for lichenysin production, in order to expand the market and applications of biosurfactants in different fields, will be discussed.
Topics: Anaerobiosis; Bacillus; Bacillus licheniformis; Lipopeptides; Oxygen; Surface-Active Agents
PubMed: 35752271
DOI: 10.1016/j.biotechadv.2022.108013 -
PloS One 2023L-asparaginase (L-ASNase) is a versatile anticancer and acrylamide reduction enzyme predominantly used in medical and food industries. However, the high specificity of...
L-asparaginase (L-ASNase) is a versatile anticancer and acrylamide reduction enzyme predominantly used in medical and food industries. However, the high specificity of L-asparaginase formulations for glutamine, low thermostability, and blood clearance are the major disadvantages. Present study describes production, characterization, and applications of glutaminase free extracellular L-asparaginase from indigenous Bacillus halotolerans ASN9 isolated from soil sample. L-asparaginase production was optimized in M9 medium (containing 0.2% sucrose and 1% L-asparagine) that yielded maximum L-ASNase with a specific activity of 256 U mg-1 at pH 6 and 37°C. L-asparaginase was purified through acetone precipitation and Sephadex G-100 column, yielding 48.9 and 24% recovery, respectively. Enzyme kinetics revealed a Vmax of 466 mM min-1 and Km of 0.097 mM. Purified L-ASNase showed no activity against glutamine. The purified glutaminase free L-ASNase has a molecular mass of 60 kDa and an optimum specific activity of 3083 U mg-1 at pH 7 and 37°C. The enzyme retains its activity and stability over a wide range of pH and temperature, in the presence of selected protein inhibitors (SDS, β-mercaptoethanol), CoCl2, KCl, and NaCl. The enzyme also exhibited antioxidant activity against DPPH radical (IC50 value 70.7 μg mL-1) and anticancer activity against U87 human malignant glioma (IC50 55 μg mL-1) and Huh7 human hepatocellular carcinoma (IC50 37 μg mL-1) cell lines. Normal human embryonic kidney cells (HEK293) had greater than 80% cell viability with purified L-ASNase indicating its least cytotoxicity against normal cells. The present work identified potent glutaminase free L-ASNase from B. halotolerans ASN9 that performs well in a wide range of environmental conditions indicating its suitability for various commercial applications.
Topics: Humans; Asparaginase; Glutamine; HEK293 Cells; Bacillus; Antineoplastic Agents
PubMed: 38015853
DOI: 10.1371/journal.pone.0288620 -
Journal of Advanced Research Jul 2023Nitrogen sources play an essential role in maintaining the physiological and biochemical activity of bacteria. Nitrogen metabolism, which is the core of microorganism... (Review)
Review
BACKGROUND
Nitrogen sources play an essential role in maintaining the physiological and biochemical activity of bacteria. Nitrogen metabolism, which is the core of microorganism metabolism, makes bacteria able to autonomously respond to different external nitrogen environments by exercising complex internal regulatory networks to help them stay in an ideal state. Although various studies have been put forth to better understand this regulation in Bacillus, and many valuable viewpoints have been obtained, these views need to be presented systematically and their possible applications need to be specified.
AIM OF REVIEW
The intention is to provide a deep and comprehensive understanding of nitrogen metabolism in Bacillus, an important industrial microorganism, and thereby apply this regulatory logic to synthetic biology to improve biosynthesis competitiveness. In addition, the potential researches in the future are also discussed.
KEY SCIENTIFIC CONCEPT OF REVIEW
Understanding the meticulous regulation process of nitrogen metabolism in Bacillus not only could facilitate research on metabolic engineering but also could provide constructive insights and inspiration for studies of other microorganisms.
Topics: Bacillus; Synthetic Biology; Nitrogen; Metabolic Engineering; Bacteria
PubMed: 36103961
DOI: 10.1016/j.jare.2022.09.003 -
Biocontrol Science 2021In this study, spore heat resistance and growth ability at refrigeration temperatures of Bacillus spp. and Paenibacillus spp. were determined. The spore D of 67.6% (23...
In this study, spore heat resistance and growth ability at refrigeration temperatures of Bacillus spp. and Paenibacillus spp. were determined. The spore D of 67.6% (23 of 34 strains) of Bacillus and 73.9% (17 of 23 strains) of Paenibacillus was less than 15 min. The growth abilities of both genera were equivalent at 10°C. However, 71.1% (32 of 45 strains) of Paenibacillus and only 6.3% (3 of 48 strains) of Bacillus cereus group could grow at 4°C. Eight B. cereus strains formed spores with higher heat resistance compared to the other Bacillus strains assessed; however, they did not grow at tempreratures below 10°C. Conversely, four Paenibacillus strains formed spores with heat resistance equivalent to that of the eight B. cereus strains and grew at 6°C or lower. In particular, Paenibacillus sp. JCM13343 formed the highest heat-resistant spores (D = 136.1 min) and grew well at 4°C. These results indicate that Paenibacillus can grow in processed foods during refrigerated storage and has the potential to cause spoilage as well as Bacillus. Therefore, Paenibacillus should be considered as one of the targets for microbiological control in refrigerated processed foods.
Topics: Bacillus; Bacillus cereus; Colony Count, Microbial; Food Microbiology; Hot Temperature; Paenibacillus; Refrigeration; Spores, Bacterial; Temperature
PubMed: 34556617
DOI: 10.4265/bio.26.147 -
Microbiology (Reading, England) May 2021is recognized as a causative agent of gastrointestinal syndromes, but can also cause a devastating form of intraocular infection known as endophthalmitis. We have...
is recognized as a causative agent of gastrointestinal syndromes, but can also cause a devastating form of intraocular infection known as endophthalmitis. We have previously reported that the PlcR/PapR master virulence factor regulator system regulates intraocular virulence, and that the S-layer protein (SlpA) contributes to the severity of endophthalmitis. To better understand the role of other virulence genes in endophthalmitis, expression of a subset of factors was measured at the midpoint of disease progression in a murine model of endophthalmitis by RNA-Seq. Several cytolytic toxins were expressed at significantly higher levels than in BHI. The virulence regulators , , and were also expressed . However, at this timepoint, / was not detectable, although we previously reported that a mutant deficient in PlcR was attenuated in the eye. The motility-related genes , , and , and the chemotaxis-related gene were detected during infection. We have shown previously that motility and chemotaxis phenotypes are important in endophthalmitis. The variant of manganese superoxide dismutase was the most highly expressed gene . Expression of the surface layer protein gene, , an activator of Toll-like receptors (TLR)-2 and -4, was also detected during infection, albeit at low levels. Genes expressed in a mouse model of endophthalmitis might play crucial roles in the unique virulence of endophthalmitis, and serve as candidates for novel therapies designed to attenuate the severity of this often blinding infection.
Topics: Animals; Bacillus cereus; Bacterial Proteins; Endophthalmitis; Female; Gene Expression Regulation, Bacterial; Humans; Male; Mice; Mice, Inbred C57BL; Virulence
PubMed: 34032564
DOI: 10.1099/mic.0.001057