scholarly journals Biosurfactant production maintains viability in anoxic conditions by depolarizing the membrane in Bacillus subtilis

2019 ◽  
Author(s):  
Heidi A. Arjes ◽  
Lam Vo ◽  
Caroline Marie Dunn ◽  
Lisa Willis ◽  
Christopher A. DeRosa ◽  
...  
Keyword(s):  
Cell Wall ◽  
Bacillus Subtilis ◽  
Membrane Potential ◽  
Stationary Phase ◽  
Optical Density ◽  
Electron Acceptor ◽  
Oxygen Depletion ◽  
Aerobic Growth ◽  
Terminal Electron Acceptor ◽  
Obligate Aerobe

SummaryThe presence or absence of oxygen in the environment is a strong effector of cellular metabolism and physiology. Like many eukaryotes and some bacteria, Bacillus subtilis is an obligate aerobe that primarily utilizes oxygen during respiration to generate ATP. Despite the importance of oxygen for B. subtilis survival, we know little about how oxygen is consumed during growth and how populations respond to shifts in oxygen availability. Here, we find that when oxygen was depleted from stationary phase cultures ∼90% of B. subtilis 3610 cells died and lysed due to autolysin activity; the remaining cells maintained colony-forming ability. Interestingly, the domesticated 168 strain maintained a higher optical density than 3610 during oxygen depletion due to the formation of cell-wall-less protoplasts, but the remaining, rod-shaped cells were >100-fold less viable than 3610. We discovered that the higher viability in 3610 was due to its ability to produce the antibacterial compound surfactin, as surfactin addition rescued 168 viability and also increased yield in aerobic growth. We further demonstrate that surfactin strongly depolarizes the B. subtilis membrane, and that other known membrane-potential disruptors restore viability to 168. These findings highlight the importance of surfactin for survival during oxygen-depleted conditions and demonstrate that antimicrobials normally considered harmful can instead benefit cells in stressful conditions when the terminal electron acceptor in respiration is limiting.

Induction of autolysis in Bacillus subtilis by ochratoxin A

1978 ◽  
Vol 24 (5) ◽  
pp. 563-568 ◽  
Author(s):  
U. Singer ◽  
R. Röschenthaler
Keyword(s):  
Cell Wall ◽  
Protein Synthesis ◽  
Bacillus Subtilis ◽  
Ochratoxin A ◽  
Optical Density ◽  
Growth Phase ◽  
Exponential Growth ◽  
Rna Synthesis ◽  
Exponential Growth Phase ◽  
Cell Wall Synthesis

Ochratoxin A (OTA) added during the exponential growth phase at a concentration higher than 12 μg/ml caused autolysis of Bacillus subtilis. Optical density of cultures decreased, and at higher concentrations the cultures became sterile. Optimum OTA-induced lysis was about pH 5. At concentrations below 10 μg/ml, protein synthesis was inhibited more strongly than RNA synthesis. Cell wall synthesis was also strongly inhibited. A fraction extracted from the lysates had the property of a lysis inhibitor. The relevance of this fraction in respect to autolysis is discussed.

scholarly journals Cannibalism as cell differentiation meant that Bacillus subtilis NRS-762 is not suitable as model organism in survivability studies of microbes

2017 ◽  
Author(s):  
Wenfa Ng
Keyword(s):  
Bacillus Subtilis ◽  
Stationary Phase ◽  
Cell Population ◽  
Optical Density ◽  
Model Organism ◽  
Cell Lysis ◽  
Model Organisms ◽  
Rapid Decline ◽  
Post Inoculation ◽  
Massive Cell

Survival of microbes on various surfaces and environment is a question of importance to basic science, as well as health care, water treatment and distribution, ecology, and search for life in other planetary bodies. To this end, various model organisms, known to be resilient against a variety of environmental insults are used for understanding the mechanisms underlying survival in extreme environments, or conditions mimicking those of the investigated habitats. Serendipitous observations of drastic decline in optical density of Bacillus subtilis NRS-762 (ATCC 8473) in LB Lennox and Tryptic Soy Broth (TSB) at temperatures of 25, 30 and 37 oC, after the aerobic culture reached maximal cell density at stationary phase, pointed to possible cell lysis as mechanism for cell death. Specifically, optical density of the bacterium declined from 5.4 at 22.5 hours post inoculation in LB Lennox to 2.5 after 38 hours of culture at 25 oC and 250 rpm rotational shaking. Similarly, optical density of B. subtilis also precipitously declined from 6.4 at 33 hours of culture to 1.8 at 51 hours post inoculation at 37 oC in TSB. This is in stark contrast to aerobic growth of Escherichia coli DH5α (ATCC 53868) in LB Lennox at 37 oC and 250 rpm, where optical density remained stable during stationary phase. More importantly, observations of B. subtilis culture after autoclave decontamination revealed lack of cellular debris; thereby, indicating massive cell lysis resulting in population collapse. Although B. subtilis is known to enter into various cellular differentiation programmes upon nutrient starvation such as onset of stationary phase in cell culture, complete absence of cell debris that usually settle at the bottom of the shake flask after autoclave decontamination, pointed to cannibalism or prophage induced cell lysis as key reasons underlying observed drastic decline in optical density of the culture. Specifically, prophage induced cell lysis may be discounted as this would have destroyed the entire cell population expeditiously shortly after entry into stationary phase. Hence, cannibalism, where a subpopulation of B. subtilis cells secrete cell lysis factors which other B. subtilis cells are not resistant to, likely result in massive cell lysis that generated cellular contents that could serve as nutrients for the surviving cell population resistant to the cell lysis factors, and may be the dominant mechanism underpinning observed rapid decline in optical density after entry into stationary phase. Collectively, B. subtilis NRS-762 is not suitable as model organism for microbial survivability studies given its tendency to undergo differentiation into the cannibalism programme, which in killing a significant fraction of cells upon nutrient deprivation, would also confound experiments aimed at understanding the resilience of cells towards various extraneous environmental factors not common in the microbe’s favoured habitats.

scholarly journals Muropeptide Rescue in Bacillus subtilis Involves Sequential Hydrolysis by β-N-Acetylglucosaminidase and N-Acetylmuramyl-l-Alanine Amidase

2010 ◽  
Vol 192 (12) ◽  
pp. 3132-3143 ◽  
Author(s):  
Silke Litzinger ◽  
Amanda Duckworth ◽  
Katja Nitzsche ◽  
Christian Risinger ◽  
Valentin Wittmann ◽  
...  
Keyword(s):  
Cell Wall ◽  
Bacillus Subtilis ◽  
Stationary Phase ◽  
Particulate Material ◽  
Late Stationary Phase ◽  
Phosphotransferase System ◽  
E Coli ◽  
A Cell ◽  
Recycling Pathway ◽  
Hydrolysis Of

ABSTRACT We identified a pathway in Bacillus subtilis that is used for recovery of N-acetylglucosamine (GlcNAc)-N-acetylmuramic acid (MurNAc) peptides (muropeptides) derived from the peptidoglycan of the cell wall. This pathway is encoded by a cluster of six genes, the first three of which are orthologs of Escherichia coli genes involved in N-acetylmuramic acid dissimilation and encode a MurNAc-6-phosphate etherase (MurQ), a MurNAc-6-phosphate-specific transcriptional regulator (MurR), and a MurNAc-specific phosphotransferase system (MurP). Here we characterized two other genes of this cluster. The first gene was shown to encode a cell wall-associated β-N-acetylglucosaminidase (NagZ, formerly YbbD) that cleaves the terminal nonreducing N-acetylglucosamine of muropeptides and also accepts chromogenic or fluorogenic β-N-acetylglucosaminides. The second gene was shown to encode an amidase (AmiE, formerly YbbE) that hydrolyzes the N-acetylmuramyl-l-Ala bond of MurNAc peptides but not this bond of muropeptides. Hence, AmiE requires NagZ, and in conjunction these enzymes liberate MurNAc by sequential hydrolysis of muropeptides. NagZ expression was induced at late exponential phase, and it was 6-fold higher in stationary phase. NagZ is noncovalently associated with lysozyme-degradable particulate material and can be released from it with salt. A nagZ mutant accumulates muropeptides in the spent medium and displays a lytic phenotype in late stationary phase. The evidence for a muropeptide catabolic pathway presented here is the first evidence for cell wall recovery in a Gram-positive organism, and this pathway is distinct from the cell wall recycling pathway of E. coli and other Gram-negative bacteria.

Metabolic profiles and aprE expression in anaerobic cultures of Bacillus subtilis using nitrate as terminal electron acceptor

2001 ◽  
Vol 57 (3) ◽  
pp. 379-384 ◽  
Author(s):  
Espinosa-de-los-Monteros J. ◽  
Martinez A. ◽  
Valle F.
Keyword(s):  
Bacillus Subtilis ◽  
Electron Acceptor ◽  
Metabolic Profiles ◽  
Terminal Electron Acceptor

Wall turnover deficiency of Bacillus subtilis Nil5 is due to a decrease in teichoic acid

1987 ◽  
Vol 33 (6) ◽  
pp. 566-568 ◽  
Author(s):  
Ljubiša Vitković
Keyword(s):  
Cell Wall ◽  
Bacillus Subtilis ◽  
Stationary Phase ◽  
Phosphorus Content ◽  
Teichoic Acid ◽  
Exponential Phase ◽  
Standard Strain ◽  
Late Exponential Phase ◽  
Wall Teichoic Acid

Bacillus subtilis Ni15 is deficient in cell wall turnover. This deficiency is removed if the medium contains 0.2 M NaCl, which does not affect growth. The levels of amidase and glucosaminidase, the most likely enzymes involved in turnover, were, in stationary phase Nil5 cells, similar to those in late-exponential phase cells of a standard strain. The Nil5 enzymes were not salt sensitive. However, the Nil5 walls contained 4.7-fold less phosphorus than the walls of the standard strain. Since the phosphorus content of B. subtilis walls reflects the level of teichoic acid, it is proposed that the turnover deficiency of this strain is due to a decrease in wall teichoic acid.

scholarly journals Drastic decline in optical density during stationary phase meant that Bacillus subtilis NRS-762 is not suitable as model organism in microbial survivability studies

2018 ◽  
Author(s):  
Wenfa Ng
Keyword(s):  
Bacillus Subtilis ◽  
Stationary Phase ◽  
Optical Density ◽  
Shake Flask ◽  
Model Organism ◽  
Cell Lysis ◽  
Nutrient Starvation ◽  
Model Organisms ◽  
Post Inoculation ◽  
Massive Cell

Survival of microbes on various surfaces and habitats is a question of importance to basic science, as well as health care, water treatment and distribution, ecology, and search for life in other planetary bodies. To this end, various model organisms known to be resilient against a variety of environmental stressors are used for understanding the mechanisms underlying survival in extreme environments, or conditions mimicking those of the investigated habitats. Observations of drastic decline in optical density of Bacillus subtilis NRS-762 (ATCC 8473) in LB Lennox and Tryptic Soy Broth (TSB) at temperatures of 25, 30 and 37 oC, after the aerobic shake flask culture reached maximal cell density at stationary phase, pointed to possible cell lysis as mechanism for cell death. Specifically, optical density of the bacterium declined from 5.4 at 22.5 hours post-inoculation in LB Lennox medium to 2.5 after 38 hours of culture at 25 oC and 250 rpm rotational shaking. Similarly, optical density of B. subtilis NRS-762 also precipitously declined from 6.4 at 33 hours of culture to 1.8 at 51 hours post-inoculation at 37 oC in TSB. This is in stark contrast to aerobic growth of Escherichia coli DH5α (ATCC 53868) in LB Lennox medium at 37 oC and 230 rpm rotational shaking, where optical density remained stable during stationary phase. More importantly, observations of B. subtilis NRS-762 culture after autoclave decontamination revealed a lack of cellular debris; thereby, indicating massive cell lysis resulting in population collapse. Although B. subtilis is known to enter into various cellular differentiation programmes upon nutrient starvation, complete absence of cell debris that usually settle at the bottom of the shake flask after autoclave decontamination pointed to cannibalism or prophage induced cell lysis as key reasons underlying observed drastic decline in optical density of the culture. However, prophage induced cell lysis may be discounted as this would have led to rapid collapse of the entire cell population shortly after entry into stationary phase except during growth of B. subtilis NRS-762 at 37 oC where a temperature sensitive sensor might have activated prophage entry into the lytic programme. Hence, cannibalism, where a subpopulation of B. subtilis NRS-762 cells secrete cell lysis factors which other B. subtilis NRS-762 cells are not resistant to, likely resulted in massive cell lysis that released cellular contents that served as nutrients for the surviving population. Collectively, B. subtilis NRS-762 is not suitable as model organism for microbial survivability studies given its tendency to undergo differentiation into the cannibalism programme, which in killing a significant fraction of cells upon nutrient starvation, would confound experiments aimed at understanding the survivability of the bacterium under a variety of environmental conditions.

scholarly journals Drastic decline in optical density during stationary phase meant that Bacillus subtilis NRS-762 is not suitable as model organism in microbial survivability studies

2018 ◽  
Author(s):  
Wenfa Ng
Keyword(s):  
Bacillus Subtilis ◽  
Stationary Phase ◽  
Optical Density ◽  
Shake Flask ◽  
Model Organism ◽  
Cell Lysis ◽  
Nutrient Starvation ◽  
Model Organisms ◽  
Post Inoculation ◽  
Massive Cell

Survival of microbes on various surfaces and habitats is a question of importance to basic science, as well as health care, water treatment and distribution, ecology, and search for life in other planetary bodies. To this end, various model organisms known to be resilient against a variety of environmental stressors are used for understanding the mechanisms underlying survival in extreme environments, or conditions mimicking those of the investigated habitats. Observations of drastic decline in optical density of Bacillus subtilis NRS-762 (ATCC 8473) in LB Lennox and Tryptic Soy Broth (TSB) at temperatures of 25, 30 and 37 oC, after the aerobic shake flask culture reached maximal cell density at stationary phase, pointed to possible cell lysis as mechanism for cell death. Specifically, optical density of the bacterium declined from 5.4 at 22.5 hours post-inoculation in LB Lennox medium to 2.5 after 38 hours of culture at 25 oC and 250 rpm rotational shaking. Similarly, optical density of B. subtilis NRS-762 also precipitously declined from 6.4 at 33 hours of culture to 1.8 at 51 hours post-inoculation at 37 oC in TSB. This is in stark contrast to aerobic growth of Escherichia coli DH5α (ATCC 53868) in LB Lennox medium at 37 oC and 230 rpm rotational shaking, where optical density remained stable during stationary phase. More importantly, observations of B. subtilis NRS-762 culture after autoclave decontamination revealed a lack of cellular debris; thereby, indicating massive cell lysis resulting in population collapse. Although B. subtilis is known to enter into various cellular differentiation programmes upon nutrient starvation, complete absence of cell debris that usually settle at the bottom of the shake flask after autoclave decontamination pointed to cannibalism or prophage induced cell lysis as key reasons underlying observed drastic decline in optical density of the culture. However, prophage induced cell lysis may be discounted as this would have led to rapid collapse of the entire cell population shortly after entry into stationary phase except during growth of B. subtilis NRS-762 at 37 oC where a temperature sensitive sensor might have activated prophage entry into the lytic programme. Hence, cannibalism, where a subpopulation of B. subtilis NRS-762 cells secrete cell lysis factors which other B. subtilis NRS-762 cells are not resistant to, likely resulted in massive cell lysis that released cellular contents that served as nutrients for the surviving population. Collectively, B. subtilis NRS-762 is not suitable as model organism for microbial survivability studies given its tendency to undergo differentiation into the cannibalism programme, which in killing a significant fraction of cells upon nutrient starvation, would confound experiments aimed at understanding the survivability of the bacterium under a variety of environmental conditions.

scholarly journals Bacterial inducible expression of plant cell wall-binding protein YesO through conflict between Glycine max and saprophytic Bacillus subtilis

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Haruka Sugiura ◽  
Ayumi Nagase ◽  
Sayoko Oiki ◽  
Bunzo Mikami ◽  
Daisuke Watanabe ◽  
...  
Keyword(s):  
Cell Wall ◽  
Bacillus Subtilis ◽  
Glycine Max ◽  
Plant Cell ◽  
Plant Cell Wall ◽  
Binding Protein ◽  
Fermented Food ◽  
Physiological Status ◽  
Soybean Seeds ◽  
Initial Growth

Abstract Saprophytic bacteria and plants compete for limited nutrient sources. Bacillus subtilis grows well on steamed soybeans Glycine max to produce the fermented food, natto. Here we focus on bacterial responses in conflict between B. subtilis and G. max. B. subtilis cells maintained high growth rates specifically on non-germinating, dead soybean seeds. On the other hand, viable soybean seeds with germinating capability attenuated the initial growth of B. subtilis. Thus, B. subtilis cells may trigger saprophytic growth in response to the physiological status of G. max. Scanning electron microscope observation indicated that B. subtilis cells on steamed soybeans undergo morphological changes to form apertures, demonstrating cell remodeling during saprophytic growth. Further, transcriptomic analysis of B. subtilis revealed upregulation of the gene cluster, yesOPQR, in colonies growing on steamed soybeans. Recombinant YesO protein, a putative, solute-binding protein for the ATP-binding cassette transporter system, exhibited an affinity for pectin-derived oligosaccharide from plant cell wall. The crystal structure of YesO, in complex with the pectin oligosaccharide, was determined at 1.58 Å resolution. This study expands our knowledge of defensive and offensive strategies in interspecies competition, which may be promising targets for crop protection and fermented food production.

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