Endospore Formation Research Articles

Milestones in Bacillus subtilis sporulation research.

Endospore formation has been a rich field of research for more than a century, and has benefited from the powerful genetic tools available in Bacillus subtilis. In this review, we highlight foundational discoveries that shaped the sporulation field, from its origins to the present day, tracing a chronology that spans more than one hundred eighty years. We detail how cell-specific gene expression has been harnessed to investigate the existence and function of intercellular proteinaceous channels in sporulating cells, and we illustrate the rapid progress in our understanding of the cell biology of sporulation in recent years using the process of chromosome translocation as a storyline. Finally, we sketch general aspects of sporulation that remain largely unexplored, and that we envision will be fruitful areas of future research.

Deltamethrin transformation by Bacillus thuringiensis and the associated metabolic pathways

The biological toxicity of deltamethrin at molecular level has been investigated, whereas, the proteome responsive mechanisms of cells under deltamethrin stress at the phylogenetic level are not clear. The proteome expression, transformation-related pathway and regulatory network of Bacillus thuringiensis during the process of deltamethrin transformation were explored using proteomics and metabolomics approaches in the present study. The results showed that deltamethrin was effectively removed by B. thuringiensis within 48 h. The stress responses of B. thuringiensis were activated to resist deltamethrin stress, with significant differential expression of proteins that were primarily involved in the synthesis of DNA and shock proteins, endospore formation, carbon metabolism. The expression patterns of ribosomal proteins confirmed that the transcription and translation of DNA, and biosynthesis of heat shock proteins were inhibited as deltamethrin transformation. The synthesis of oxaloacetate and acetyl-CoA were also hindered, resulting in downregulated expression of carbohydrate metabolism, TCA cycle and energy metabolism. Meanwhile, endospore formation and germination were promoted to resist oxidative stress induced by deltamethrin. These findings imparted novel insight to elucidate underlying stress response mechanisms of the organism under target contaminants stress, and the interaction between deltamethrin transformation and cellular metabolism at the pathway and network levels.

Cohesion of Sister Chromosome Termini during the Early Stages of Sporulation in Bacillus subtilis.

During sporulation of Bacillus subtilis, the cell cycle is reorganized to generate separated prespore and mother cell compartments, each containing a single fully replicated chromosome. The process begins with reorganization of the nucleoid to form an elongated structure, the axial filament, in which the two chromosome origins are attached to opposite cell poles, with the remainder of the DNA stretched between these sites. When the cell then divides asymmetrically, the division septum closes around the chromosome destined for the smaller prespore, trapping the origin-proximal third of the chromosome in the prespore. A translocation pore is assembled through which a DNA transporter, SpoIIIE/FtsK, transfers the bulk of the chromosome to complete the segregation process. Although the mechanisms involved in attaching origin regions to the cell poles are quite well understood, little is known about other aspects of axial filament morphology. We have studied the behavior of the terminus region of the chromosome during sporulation using time-lapse imaging of wild-type and mutant cells. The results suggest that the elongated structure involves cohesion of the terminus regions of the sister chromosomes and that this cohesion is resolved when the termini reach the asymmetric septum or translocation pore. Possible mechanisms and roles of cohesion and resolution are discussed.IMPORTANCE Endospore formation in Firmicutes bacteria provides one of the most highly resistant life forms on earth. During the early stages of endospore formation, the cell cycle is reorganized so that exactly two fully replicated chromosomes are generated, before the cell divides asymmetrically to generate the prespore and mother cell compartments that are critical for the developmental process. Decades ago, it was discovered that just prior to asymmetrical division the two chromosomes enter an unusual elongated configuration called the axial filament. This paper provides new insights into the nature of the axial filament structure and suggests that cohesion of the normally separated sister chromosome termini plays an important role in axial filament formation.

Shaping an Endospore: Architectural Transformations During Bacillus subtilis Sporulation.

Endospore formation in Bacillus subtilis provides an ideal model system for studying development in bacteria. Sporulation studies have contributed a wealth of information about the mechanisms of cell-specific gene expression, chromosome dynamics, protein localization, and membrane remodeling, while helping to dispel the early view that bacteria lack internal organization and interesting cell biological phenomena. In this review, we focus on the architectural transformations that lead to a profound reorganization of the cellular landscape during sporulation, from two cells that lie side by side to the endospore, the unique cell within a cell structure that is a hallmark of sporulation in B. subtilis and other spore-forming Firmicutes. We discuss new insights into the mechanisms that drive morphogenesis, with special emphasis on polar septation, chromosome translocation, and the phagocytosis-like process of engulfment, and also the key experimental advances that have proven valuable in revealing the inner workings of bacterial cells.

Defining Critical Genes During Spherule Remodeling and Endospore Development in the Fungal Pathogen, Coccidioides posadasii.

Coccidioides immitis and C. posadasii are soil dwelling dimorphic fungi found in North and South America. Inhalation of aerosolized asexual conidia can result in asymptomatic, acute, or chronic respiratory infection. In the United States there are approximately 350,000 new infections per year. The Coccidioides genus is the only known fungal pathogen to make specialized parasitic spherules, which contain endospores that are released into the host upon spherule rupture. The molecular determinants involved in this key step of infection remain largely elusive as 49% of genes are hypothetical with unknown function. An attenuated mutant strain C. posadasii Δcts2/Δard1/Δcts3 in which chitinase genes 2 and 3 were deleted was previously created for vaccine development. This strain does not complete endospore development, which prevents completion of the parasitic lifecycle. We sought to identify pathways active in the wild-type strain during spherule remodeling and endospore formation that have been affected by gene deletion in the mutant. We compared the transcriptome and volatile metabolome of the mutant Δcts2/Δard1/Δcts3 to the wild-type C735. First, the global transcriptome was compared for both isolates using RNA sequencing. The raw reads were aligned to the reference genome using TOPHAT2 and analyzed using the Cufflinks package. Genes of interest were screened in an in vivo model using NanoString technology. Using solid phase microextraction (SPME) and comprehensive two-dimensional gas chromatography – time-of-flight mass spectrometry (GC × GC-TOFMS) volatile organic compounds (VOCs) were collected and analyzed. Our RNA-Seq analyses reveal approximately 280 significantly differentially regulated transcripts that are either absent or show opposite expression patterns in the mutant compared to the parent strain. This suggests that these genes are tied to networks impacted by deletion and may be critical for endospore development and/or spherule rupture in the wild-type strain. Of these genes, 14 were specific to the Coccidioides genus. We also found that the wild-type and mutant strains differed significantly in their production versus consumption of metabolites, with the mutant displaying increased nutrient scavenging. Overall, our results provide the first targeted list of key genes that are active during endospore formation and demonstrate that this approach can define targets for functional assays in future studies.

Screening of native ureolytic bacteria for self-healing in cementitious materials

In recent years, microbial calcium carbonate has been recognised for its potential to self-heal cementitious material by mimicking the natural biological systems of healing wounds. Thus, the inevitable microcracks and concrete pores can be filled with microbial calcium carbonate to prevent any aggressive chemical flow or water and prolong the life span of the structure. Recently, numerous studies have reported on bio-concrete incorporating bacterial species such as B. sphaericus and B. pasteruii, although there are limited studies on the B. pseudomycoides species. In this study, new native ureolytic bacteria were isolated from soil samples collected in Universiti Teknologi Malaysia. The morphology, characteristics, and ureolytic production of the bacteria were investigated through biochemical tests. The bacterial enhancement efficiency of the concrete compressive strength was also examined. The results demonstrated that the bacteria are gram-positive with encouraging characteristics such as endospore formation, which is required for application in harsh environments such as concrete. The native bacteria also demonstrated high urease enzyme productivity. Furthermore, the applicability of the bacterial spores and vegetative cells-urea solution as a healing agent in concrete was demonstrated by increasing concrete compressive strength by 10% and 15% compared to the control sample with the optimum cell concentration of 2×107 cell/ml. This finding was attributed to the precipitation of calcium carbonate in the pore volume and confirmed by X-ray diffraction (XRD).

A method for the preparation of electrocompetent cells to transform unicellular green algae, Coccomyxa (Trebouxiophyceae, Chlorophyta) strains Obi and KJ

Unicellular green algae, Coccomyxa spp. strains Obi and KJ are capable of growing at broad pH ranges, and accumulate lipids at levels higher than 50% of the dry cell weight under nitrogen-depleted conditions. An efficient genetic transformation method applicable to the two strains is required for their genetic improvement to facilitate their application in commercial production of biofuels. After an extended trial and error period, we fortuitously determined conditions required for the transformation of the strains through electroporation. First, the growth of the strains in isotonic medium e.g., minimal salt medium containing 0.6 M sorbitol or mannitol was required. Second, the growth under a light/dark cycle was critical. In the dark period in the cycle, cells contained two or four endospores surrounded by a mother-cell wall. Within half an hour after the beginning of the light period, the mother-cell wall was cleaved, and unicellular autospores that were electrocompetent were released. The application of a single electroporation pulse at an electric-field strength of 10 kV cm−1 to the autospores yielded transformants at a frequency of >10−6 per input cell for strain KJ and >10−7 per input cell for strain Obi. The transformation method is relatively simple, and provided several to several dozen higher transformation frequencies than those applying the biolistic bombardment method that we previously developed. The present study also provides insights that could facilitate the development of genetic transformation systems for microalgae, which reproduce by endospore formation.

RRNPP-type quorum sensing affects solvent formation and sporulation in Clostridium acetobutylicum.

The strictly anaerobic bacterium Clostridium acetobutylicum is well known for its ability to convert sugars into organic acids and solvents, most notably the potential biofuel butanol. However, the regulation of its fermentation metabolism, in particular the shift from acid to solvent production, remains poorly understood. The aim of this study was to investigate whether cell–cell communication plays a role in controlling the timing of this shift or the extent of solvent formation. Analysis of the available C. acetobutylicum genome sequences revealed the presence of eight putative RRNPP-type quorum-sensing systems, here designated qssA to qssH, each consisting of an RRNPP-type regulator gene followed by a small open reading frame encoding a putative signalling peptide precursor. The identified regulator and signal peptide precursor genes were designated qsrA to qsrH and qspA to qspH, respectively. Triplicate regulator mutants were generated in strain ATCC 824 for each of the eight systems and screened for phenotypic changes. The qsrB mutants showed increased solvent formation during early solventogenesis and hence the QssB system was selected for further characterization. Overexpression of qsrB severely reduced solvent and endospore formation and this effect could be overcome by adding short synthetic peptides to the culture medium representing a specific region of the QspB signalling peptide precursor. In addition, overexpression of qspB increased the production of acetone and butanol and the initial (48 h) titre of heat-resistant endospores. Together, these findings establish a role for QssB quorum sensing in the regulation of early solventogenesis and sporulation in C. acetobutylicum .

Hyphopichia lachancei, f.a., sp. nov., a yeast species from diverse origins.

Three strains originating from insect frass in South Africa, yellow foxglove in Hungary and soil in France, were characterised phenotypically and by sequencing of the D1/D2 domain of the large subunit and the ITS1-5.8S-ITS2 (ITS)-region of the rRNA gene. The strains have identical D1/D2 domain sequences and only one strain shows a 1bp indel in a 9bp homopolymer A/T repeat within the ITS-region. Based on sequence analysis Hyphopichia burtonii is the closest related species. The investigated strains differ from the type strain of H. burtonii by 1.9% (9 substitutions and an indel) in the D1/D2 domain and by 23 substitutions and 21-22 indels in the ITS-region. Since the sequence variability is very low among the three strains and the sequence divergence with the closely related H. burtonii exceeds the level generally encountered between species we propose the new species Hyphopichia lachancei f.a., sp. nov. to accommodate the three novel strains. From H. burtonii the new species can be distinguished phenotypically by its inability to ferment cellobiose and by the formation of endospores (Holotype: CBS 5999T; Isotype: NCAIM Y.02228T; MycoBank no.: MB833616).

Screening and Isolation of Spore forming thermophilic Bacteria from Zharkent hot spring

The purpose of this study is screening and isolation of thermophilic microorganisms from a geothermal hot spring in Zharkent, Almaty region, Kazakhstan. The phylogenetic diversity and screening of theprokaryotic community thriving in Zharkent geothermal hot spring has been studied by microbiologicalmethods. The study confirmed that isolates from Zharkent geothermal hot spring are true thermophilesaccording to experiments and can be a source of thermostable enzymes; three isolates (AC1W, AC1S,AC4S) out of eight showed good enzymatic characteristics based on the results of their cultivation onselective media. Isolated thermophilic microorganisms, were cultivated under different conditions, suchas: temperature (50, 60, 70, 80, and 95оC), selective media (for the amylase, cellulase, and lipase producer), different pH (5, 6, 7, 8, and 10). Morphological features of the isolated bacterial strains wereexamined by scanning electron microscopy (SEM).Based on the data of biochemical tests and morphological characteristics (endospore formation,aerobic, positive for catalase and oxidase, optimal growth temperature of 75-85 °C and the optimal pHrange of growth is 7.5-8), isolated bacteria were presumably listed in the genus Geobacillus. Thus, ourresearch has shown that there is a rich variety of thermophilic microorganisms in Zharkent hot springs,which must be studied to obtain commercially important enzymes.Key words: hyperthermophiles, hydrolase, extremozymes, isolates

Plant growth promoting and antifungal activity in endophytic Bacillus strains from pearl millet (Pennisetum glaucum).

Bacterial endophytes are well known inhabitants of living plant system and perform important assignments in maintaining plant growth and health. Currently, limited reports are available on the endophytes of pearl millet (Pennisetum glaucum) reflecting antagonistic and plant growth promoting (PGP) attributes. Therefore, the major objectives of current investigation were to identify antagonistic strains of endophytic Bacillus from pearl millet and further illustrate their PGP capabilities. In this study, 19 endophytic Bacillus strains (EPP5, EPP21, EPP30, EPP32, EPP35, EPP42, EPP49, EPP55, EPP62, EPP65, EPP70, EPP71, EPP74, EPP78, EPP83, EPP86, EPP93, EPP100, and EPP102) displaying antagonistic activity towards Rhizoctonia solani (RS), Sclerotium rolfsii (SR), and Fusarium solani (FS) were isolated from different sections (root, leaf, stem, and root) of pearl millet. Phenotypic (shape, colony, gram staining reaction, endospore formation, and motility) and biochemical features (catalase, oxidase, citrate, gelatinase, urease, Voges Proskauer's, methyl red, indole, and nitrate reduction), along with the similarly comparison of 16S rRNA gene sequence with type strains identified eight antagonistic endophyhtes as B. amyloliquefaciens (EPP35, EPP 42, EPP62, and EPP 102), Bacillus subtilis subsp. subtilis (EPP65), and Bacillus cereus (EPP5, EPP71, and EPP74). The production of indole acetic acid and siderophores was varied among the isolated endophytes. Besides displaying enzymatic activities, these isolates varied in solubilizing capabilities of phosphate, potassium, and zinc. The presence of three antimicrobial peptide genes (ituD, bmyC, and srfA) also confirmed their antifungal nature. Further, single treatment of three promising strains (EPP5, EPP62, and EPP65) offered protection ranging from 35.68 to 45.74% under greenhouse conditions. However, microbial consortium (EPP5+ EPP62 + EPP65) provided the highest protection (71.96%) against root rot and wilt infection with significant increase in plant biomass. Overall, the current study indicated that pearl millet plant harbors various species of endophytic Bacillus that possess excellent biocontrol and growth promotion activities.

Impact of CodY protein on metabolism, sporulation and virulence in Clostridioides difficile ribotype 027.

Toxin synthesis and endospore formation are two of the most critical factors that determine the outcome of infection by Clostridioides difficile. The two major toxins, TcdA and TcdB, are the principal factors causing damage to the host. Spores are the infectious form of C. difficile, permit survival of the bacterium during antibiotic treatment and are the predominant cell form that leads to recurrent infection. Toxin production and sporulation have their own specific mechanisms of regulation, but they share negative regulation by the global regulatory protein CodY. Determining the extent of such regulation and its detailed mechanism is important for understanding the linkage between two apparently independent biological phenomena and raises the possibility of creating new ways of limiting infection. The work described here shows that a codY null mutant of a hypervirulent (ribotype 027) strain is even more virulent than its parent in a mouse model of infection and that the mutant expresses most sporulation genes prematurely during exponential growth phase. Moreover, examining the expression patterns of mutants producing CodY proteins with different levels of residual activity revealed that expression of the toxin genes is dependent on total CodY inactivation, whereas most sporulation genes are turned on when CodY activity is only partially diminished. These results suggest that, in wild-type cells undergoing nutrient limitation, sporulation genes can be turned on before the toxin genes.

Study of Bacillus subtilis response to different forms of silver

Although silver nanoparticles are the most widespread product of nanotechnology, the mechanisms underlying AgNP microbial toxicity remain the subject of intense debate. In this study, Bacillus subtilis has been used as model organism to elucidate the molecular interactions between this class of bacteria and different forms of silver such as nanoparticles, nanoparticles functionalized with tetracycline and silver ions. For this purpose, we carried out transmission electron microscopy and MALDI-TOF MS analysis of cells treated with silver nanoparticles (AgNPs, AgNPs functionalized with tetracycline, combination of AgNPs with tetracycline) and silver ions as well as we measured the level of reactive oxygen species. The data demonstrate that B. subtilis exhibits high resistance to silver nanoparticles and this phenomenon is associated with following processes: (I) initiation of endospore formation, (II) reduction of free Ag+ released from nanoparticles and (III) modification of the AgNPs surface. However, high silver ions concentration appeared to be very toxic to studied strain of bacterium. MALDI-TOF MS analysis revealed that the spectra of B. subtilis cells treated with silver ions are significantly different from spectra of control cells and cell treated with AgNPs and antibiotic which can suggest that silver ions in the highest degree modify bacterial components.

Genome Sequencing and Annotation of Bacillus subtilis UBBS-14 to Ensure Probiotic Safety.

Bacillus subtilis is a rod shaped, gram positive, spore producing bacterium. They are the normal flora of gastrointestinal tract of humans and it is the best characterized model organism for endospore formation. It has the ability to withstand environmental stress, and synthesize beneficial compounds, therefore, it is recognized as a high-quality probiotic supplement. To ensure the probiotic safety and the efficiency, we report the whole genome sequence (WGS) of Bacillus subtilis UBBS-14 strain. The draft genome sequence of Bacillus subtilis UBBS-14 consists of 4,048,984 bp and 4,017 genes, respectively. Bacillus subtilis UBBS-14 does not carry any antibiotic resistant genes containing plasmid, nor it contains any harmful putative virulence factors coding genes, therefore, it confirms the probiotic safety of the respective strain at genome level.

Inactivation efficiency of Bacillus endospores via modified flow-through PUV treatment with comparison to conventional LPUV treatment

Water is a fragile resource, consequently there is a pressing need to develop sustainable environmental-friendly disinfection technologies. This constitutes the first study to compare efficacy of continuous low-pressure UV (LPUV) to that of pulsed UV light (PUV) for UV disinfection performance in flow-through water systems. Bacillus endospores were used as these are frequently deployed as biodosimeters for drinking water UV reactor validation protocols. Results showed a PUV system output of 2,052 mJ/cm2 (energy below 300 nm) was required for a 2 log inactivation of B.pumilus endospores, whereas a lower LPUV system output of 12 mJ/cm2 produced a similar level of disinfection. Measurements of dose incident to the samples (which were 10.75 cm from the PUV light source) showed supplementation of cultivation media with manganese sulphate monohydrate (MnSO4.H2O) employed to enhance the rate of endospore formation for propagation was shown to increase the UV resistance of different Bacillus spp. to both irradiation approaches (P < 0.05). Conventional LPUV light that is commonly-used by the drinking water industry is a reliable and superior approach to PUV which requires substantial modification for effective disinfection of continuous flow-through water. Caution must also be exercised when manipulating media formulation to propagate endospores as this may lead to inconsistencies in reporting efficacy of intervention treatments with implications for validation and environmental evaluation.

What Are the Multi-Omics Mechanisms for Adaptation by Microorganisms to High Alkalinity? A Transcriptomic and Proteomic Study of a Bacillus Strain with Industrial Potential.

Alkaliphilic organisms are among an industrially important class of extremophile microorganisms with the ability to thrive at pH 10-11.5. Microorganisms that exhibit alkaliphilic characteristics are sources of alkali-tolerant enzymes such as proteases, starch degrading enzymes, cellulases, and metabolites such as antibiotics, enzyme inhibitors, siderophores, organic acids, and cholic acid derivatives, which have found various applications in industry for human and environmental health. Yet, multi-omics mechanisms governing adaptation to high alkalinity have been poorly studied. We undertook the present work to understand, as a case study, the alkaliphilic adaptation strategy of the novel microorganism, Bacillus marmarensis DSM 21297, to alkaline conditions using a multi-omics approach that employed transcriptomics and proteomics. As alkalinity increased, bacteria remodeled the peptidoglycan layer by changing peptide moieties along with the peptidoglycan constituents and altered the cell membrane to reduce lipid motility and proton leakiness to adjust intracellular pH. Different transporters also contributed to the maintenance of this pH homeostasis. However, unlike in most well-known alkaliphiles, not only sodium ions but also potassium ions were involved in this process. Interestingly, increased pH has triggered the expression of neither general stress proteins nor gene encoding proteins associated with heat, salt, and nutrient stresses. Only an increase in the expression of oxidative stress related genes was evident. Endospore formation, also a phenomenon closely linked to stress, was unclear. This questioned if high pH was a real stress for B. marmarensis. These new findings, corroborated using the multi-omics approach of the present case study, broaden the knowledge on the mechanisms of alkaliphilic adaptation and might also potentially offer useful departure points for further industrial applications with other microorganisms.

Peculiarities and biotechnological potential of environmental adaptation by Geobacillus species.

The genus Geobacillus comprises thermophilic bacilli capable of endospore formation. The members of this genus provide thermostable proteins and can be used in whole cell applications at elevated temperatures; therefore, these organisms are of biotechnological importance. While these applications have been described in previous reviews, the present paper highlights the environmental adaptations and genome diversifications of Geobacillus spp. and their applications in evolutionary-protein engineering. Despite their obligate thermophilic properties, Geobacillus spp. are widely distributed in nature. Because several isolates demonstrate remarkable properties for cell reproduction in their respective niches, they seem to exist not only as endospores but also as vegetative cells in diverse environments. This suggests their excellence in environmental adaptation via genome diversification; in fact, evidence suggests that Geobacillus spp. were derived from Bacillus spp. while diversifying their genomes via horizontal gene transfer. Moreover, when subjected to an environmental stressor, Geobacillus spp. diversify their genomes using inductive mutations and transposable elements to produce derivative cells that are adaptive to the stressor. Notably, inductive mutations in Geobacillus spp. occur more rapidly and frequently than the stress-induced mutagenesis observed in other microorganisms. Owing to this, Geobacillus spp. can efficiently generate mutant genes coding for thermostable enzyme variants from the thermolabile enzyme genes under appropriate selection pressures. This phenomenon provides a new approach to generate thermostable enzymes, termed as thermoadaptation-directed enzyme evolution, thereby expanding the biotechnological potentials of Geobacillus spp. In this review, we have discussed this approach using successful examples and major challenges yet to be addressed.

Endospore forming bacteria may be associated with maintenance of surgically-induced remission in Crohn\u2019s disease

Crohn’s disease (CD) patients who undergo ileocolonic resection (ICR) typically have disease recurrence at the anastomosis which has been linked with a gut dysbiosis. The aims of this study were to define the mucosa-associated microbiota at the time of ICR and to determine if microbial community structure at the time of surgery was predictive of future disease relapse. Ileal biopsies were obtained at surgery and after 6 months from CD subjects undergoing ICR. Composition and function of mucosal-associated microbiota was assessed by 16S rRNA sequencing and PICRUSt analysis. Endoscopic recurrence was assessed using the Rutgeerts score. Analysis of mucosal biopsies taken at the time of surgery showed that decreased Clostridiales together with increased Enterobacteriales predicted disease recurrence. An increase in the endospore-forming Lachnospiraceae from surgery to 6 months post-ICR was associated with remission. A ratio of 3:1 between anaerobic endospore-forming bacterial families and aerobic families within the Firmicutes phylum was predictive of maintenance of remission. Gut recolonization following ICR is facilitated by microbes which are capable of either aerobic respiration or endospore formation. The relative proportions of these species at the time of surgery may be predictive of subsequent microbial community restoration and disease recurrence.

Physico-chemical factors influencing spore germination in cyanobacterium Fischerella muscicola.

Spore (akinete) formation in the heterocystous and branched filamentous cyanobacterium Fischerella muscicola involves a significant increase in cell size and formation of several endospores in each of the cells. In present study, the physico-chemical factors (pH, light sources, nutrient deficiency, nitrogen sources, carbon sources, and growth hormones) affecting the germination of spores of F. muscicola were examined. Increase in spore germination frequency was detected above pH 8 with maximum germination (46.04%) recorded at pH 9, whereas a significant decrease in germination was observed at pH 6 when compared to control (pH 7.6). Spore germination was not observed at pH 5. Among light sources germination frequency followed the following order, that is, red light (39.9%) > white light (33.8%) > yellow light (3.4%) > green light (1.3%) whereas germination did not take place in dark and blue light. Ammonium chloride (NH4 Cl) supported maximum (99.5%) germination frequency followed by calcium nitrate (Ca(NO3 )2 ), potassium nitrate (KNO3 ), and minimum germination was observed in urea. Nutrient (phosphorus, calcium, and magnesium) deficiency significantly enhanced the germination frequency with maximum increase in magnesium (Mg) deficient condition. Further, supplementation of carbon sources (glucose, fructose, and sodium acetate) and growth hormones (IAA and GA) also enhanced the germination frequency in this cyanobacterium. Therefore, it may be concluded that, those factors supporting higher germination frequency could be considered for successful production and use of this cyanobacterium in biofertilizer and other algal production technologies.

Endospores and other lysis-resistant bacteria comprise a widely shared core community within the human microbiota.

Endospore-formers in the human microbiota are well adapted for host-to-host transmission, and an emerging consensus points to their role in determining health and disease states in the gut. The human gut, more than any other environment, encourages the maintenance of endospore formation, with recent culture-based work suggesting that over 50% of genera in the microbiome carry genes attributed to this trait. However, there has been limited work on the ecological role of endospores and other stress-resistant cellular states in the human gut. In fact, there is no data to indicate whether organisms with the genetic potential to form endospores actually form endospores in situ and how sporulation varies across individuals and over time. Here we applied a culture-independent protocol to enrich for endospores and other stress-resistant cells in human feces to identify variation in these states across people and within an individual over time. We see that cells with resistant states are more likely than those without to be shared among multiple individuals, which suggests that these resistant states are particularly adapted for cross-host dissemination. Furthermore, we use untargeted fecal metabolomics in 24 individuals and within a person over time to show that these organisms respond to shared environmental signals, and in particular, dietary fatty acids, that likely mediate colonization of recently disturbed human guts.