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Concept: Endospore


Fungal-bacterial interactions are highly diverse and contribute to many ecosystem processes. Their emergence under common environmental stress scenarios however, remains elusive. Here we use a synthetic microbial ecosystem based on the germination of Bacillus subtilis spores to examine whether fungal and fungal-like (oomycete) mycelia reduce bacterial water and nutrient stress in an otherwise dry and nutrient-poor microhabitat. We find that the presence of mycelia enables the germination and subsequent growth of bacterial spores near the hyphae. Using a combination of time of flight- and nanoscale secondary ion mass spectrometry (ToF- and nanoSIMS) coupled with stable isotope labelling, we link spore germination to hyphal transfer of water, carbon and nitrogen. Our study provides direct experimental evidence for the stimulation of bacterial activity by mycelial supply of scarce resources in dry and nutrient-free environments. We propose that mycelia may stimulate bacterial activity and thus contribute to sustaining ecosystem functioning in stressed habitats.

Concepts: Bacteria, Plant, Fungus, Nitrogen, Bacillus, Mycelium, Bacillus subtilis, Endospore


In this work, removal of arsenic (III) from aqueous solution by living cells (Bacillus cereus), biosorption mechanism, and characterization studies have been reported. B. cereus cell surface was characterized using SEM-EDX and FTIR. Dependence of biosorption on pH of the solution, biosorbent dose, initial arsenic (III) concentration, contact time, and temperature had been studied to achieve optimum condition. The maximum biosorption capacity of living cells of B. cereus for arsenic (III) was found to be 32.42 mg/g at pH 7.5, at optimum conditions of contact time of 30 min, biomass dosage of 6 g/L, and temperature of 30 ± 2 °C. Biosorption data of arsenic (III) are fitted to linearly transformed Langmuir isotherm with R (2) (correlation coefficient) > 0.99. The pseudo-second-order model description of the kinetics of arsenic (III) is successfully applied to predict the rate constant of biosorption. Thermodynamic parameters reveal the endothermic, spontaneous, and feasible nature of sorption process of arsenic (III) onto B. cereus biomass. The arsenic (III) ions are desorbed from B. cereus using both 1 M HCl and 1 M HNO(3).

Concepts: Bacteria, Concentration, Chemistry, Thermodynamics, Bacillus, Solutions, Endospore, Bacillus cereus


Cyanogenic food crops abound in nature with important crops like cassava forming the staple food for over half a billion people. Detoxification by hydrolysis of cassava cyanogenic glycosides often involves acid fermentation, and in some of these processes Bacillus species are encountered. Forty Bacillus spp. (20 Bacillus subtilis, 11 Bacillus licheniformis, 7 Bacillus sonorensis, 2 Bacillus cereus) isolated from acid fermented primary starters to produce Gergoush, a Sudanese fermented snack, were screened for their ability to grow and to hydrolyze linamarin, the major cyanogen found in cassava at pH levels below 5.0; also the cyanogen amygdalin was assessed. The B. subtilis isolates grew in both HCl and lactic acid environments from pH4.5-6.0 while being able to break down the cyanogenic glycosides. The B. licheniformis and B. sonorensis isolates grew and degraded cyanogens at pH5.0 in a HCl environment, while two B. cereus isolates used in the study showed no breakdown reaction under all conditions tested. One B. subtilis isolate was observed to have substrate specificity between the breakdown of linamarin and amygdalin. We conclude that some Bacillus spp. isolates are important in the microbiological breakdown of cyanogens in cassava fermentations even at pH4.5-5.0 though further investigations are required.

Concepts: Enzyme, Bacillus, Cassava, Bacillus subtilis, Endospore, Fermentation, Bacillaceae, Bacillus cereus


Evaluating different swabbing materials for spore recovery efficiency (RE) from steel surfaces, we recorded the maximum RE (71%) of 10(7) Bacillus subtilis spores with Tulips cotton buds, followed by Johnson’s cotton buds and standard Hi-Media cotton, polyester, nylon, and foam (23%) swabs. Among cotton swabs, instant water-absorbing capacity or the hydrophilicity index appeared to be the major indicator of RE, as determined by testing three more brands. Tulips swabs worked efficiently across diverse nonporous surfaces and on different Bacillus spp., registering 65 to 77% RE.

Concepts: Cotton, Spore, Bacillus, Asexual reproduction, Bacillus subtilis, Endospore, American inventions, Cotton swab


The ability of six protease-producing Bacillus species (Bacillus pumilus A1, Bacillus mojavencis A21, Bacillus licheniformis RP1, Bacillus cereus SV1, Bacillus amyloliquefaciens An6 and Bacillus subtilis A26) to ferment media containing only shrimp shell waste, for chitin extraction, was investigated. More than 80% deproteinization was attained by all the strains tested. However, demineralization rates not exceeding 67% were registered. Cultures conducted in media containing shrimp shell waste supplemented with 5% (w/v) glucose were found to remarkably promote demineralization efficiency, without affecting deproteinization rates. The antioxidant activities of hydrolysates, at different concentrations, produced during fermentation in medium supplemented with glucose, were determined using different tests: 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging method, reducing power assay and chelating activity. All hydrolysates showed varying degrees of antioxidant activity. Hydrolysate produced by B. pumilus A1 exhibited the highest DPPH radical scavenging activity, with an IC(50) value of 0.3mg/ml. Highest reducing power (DO 700nm=1.55 at 1.5mg/ml) and metal chelating activity (98% at 5mg/ml) were obtained with B. pumilus A1 and B. licheniformis RP1 hydrolysates, respectively.

Concepts: Bacteria, Vitamin C, Bacillus, Bacillus subtilis, Endospore, Bacillus amyloliquefaciens, Bacillus cereus, Bacillus licheniformis


Bacillus subtilis endospores have applications in different fields including their use as probiotics and antigen delivery vectors. Such specialized applications frequently require highly purified spore preparations. Nonetheless, quantitative data regarding both yields and purity of B. subtilis endospores after application of different growth conditions and purification methods are scarce or poorly reported. In the present study, we conducted several quantitative and qualitative analyses of growth conditions and purification procedures aiming generation of purified B. subtilis spores. Based on two growth media and different incubations conditions, sporulation frequencies up to 74.2 % and spore concentrations up to 7 × 10(9) spores/ml were achieved. Application of a simplified spore isolation method, in which samples were incubated with lysozyme and a detergent, resulted in preparations with highly purified spores at the highest yields. The present study represents, therefore, an important contribution for those working with B. subtilis endospores for different biotechnological purposes.

Concepts: Bacteria, Microbiology, Qualitative research, Spore, Bacillus, Quantitative research, Bacillus subtilis, Endospore


Bacillus spores are highly resistant dormant cells formed in response to starvation. The spore is surrounded by a structurally complex protein shell, the coat, which protects the genetic material. In spite of its dormancy, once nutrient is available (or an appropriate physical stimulus is provided) the spore is able to resume metabolic activity and return to vegetative growth, a process requiring the coat to be shed. Spores dynamically expand and contract in response to humidity, demanding that the coat be flexible. Despite the coat’s critical biological functions, essentially nothing is known about the design principles that allow the coat to be tough but also flexible and, when metabolic activity resumes, to be efficiently shed. Here, we investigated the hypothesis that these apparently incompatible characteristics derive from an adaptive mechanical response of the coat. We generated a mechanical model predicting the emergence and dynamics of the folding patterns uniformly seen in Bacillus spore coats. According to this model, spores carefully harness mechanical instabilities to fold into a wrinkled pattern during sporulation. Owing to the inherent nonlinearity in their formation, these wrinkles persist during dormancy and allow the spore to accommodate changes in volume without compromising structural and biochemical integrity. This characteristic of the spore and its coat may inspire design of adaptive materials.

Concepts: Protein, Bacteria, Nutrition, Organism, Lipid, Spore, Endospore, Plant reproduction


Fidaxomicin (FDX) is approved to treat Clostridium difficile associated diarrhea, and is superior to vancomycin in providing a sustained clinical response (cure without recurrence in the subsequent 25 days). Mechanism(s) behind the low recurrence rate of FDX-treated patients could be multifactorial. Here, we tested effects of FDX, its metabolite OP-1118, and vancomycin on spore germination and determined that none affected the initiation of spore germination but all inhibited outgrowth of vegetative cells from germinated spores.

Concepts: Spore, Germination, Asexual reproduction, Clostridium difficile, Endospore, Plant reproduction


The general stress response and the decision-making processes of sporulation initiation are interconnected pathways in the regulatory network of Bacillus subtilis. In a previous study we provided evidence for a mechanism capable of impairing sporulation by σ(B) -dependent induction of spo0E, encoding a phosphatase specifically inactivating the sporulation master regulator Spo0A∼P. Here we show that the σ(B) promoter (Pσ(B) ) of spo0E is responsive to sub-inhibitory levels of ethanol stress, producing a σ(B) -dependent sporulation deficient phenotype. In addition to positive regulation by σ(B) , we identified Rok, the repressor of comK, to be a direct repressor of spo0E expression from Pσ(B) . This constellation provides the possibility to integrate signals negatively acting on sporulation initiation through the σ(B) branch as well as a positive feedback loop acting on Pσ(B) by Rok that is most likely a direct consequence of Spo0A∼P activity. Thus, the molecular mechanism described here offers the opportunity for cross-talk between the general stress response and sporulation initiation in the adaptational gene expression network of B. subtilis.

Concepts: DNA, Gene, Gene expression, Transcription, Bacillus, Feedback, Bacillus subtilis, Endospore


Antimicrobial peptides are promising alternative antimicrobial agents compared to conventional antibiotics. Understanding the mode of action is important for their further application. We examined the interaction between trichokonin VI, a peptaibol isolated from Trichoderma pseudokoningii, and Bacillus subtilis, a representative Gram-positive bacterium. Trichokonin VI was effective against B. subtilis with a minimal inhibitory concentration of 25 µM. Trichokonin VI exhibited a concentration- and time-dependent effect against B. subtilis, which was studied using atomic force microscopy. The cell wall of B. subtilis collapsed and the roughness increased upon treatment with trichokonin VI. Nanoindentation experiments revealed a progressive decrease in the stiffness of the cells. Furthermore, the membrane permeabilization effect of trichokonin VI on B. subtilis was monitored, and the results suggest that the leakage of intracellular materials is a possible mechanism of action for trichokonin VI, which led to alterations in the morphological and nanomechanical properties of B. subtilis.

Concepts: Bacteria, Amino acid, Microbiology, Cell membrane, Bacillus, Bacillus subtilis, Endospore, Firmicutes