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Frontiers in Microbiology 2021Biofuel derived from halophytic biomass is getting attention owing to the concerns of energy versus food crisis. The disadvantages associated with edible bioenergy...
Biofuel derived from halophytic biomass is getting attention owing to the concerns of energy versus food crisis. The disadvantages associated with edible bioenergy resources necessitate the need to explore new feedstocks for sustainable biofuel production. In this study, biomass from locally available abundant halophytes (, , , and ) was screened for saccharification by an enzyme cocktail composed of cellulase, xylanase, and pectinase from UE10 and UE27, UE25, UE1, and MH 1. Two types of pretreatment, i.e., with dilute acid and freeze-thaw, were independently applied to the halophytic biomass. Saccharification of acid-pretreated biomass yielded maximum reducing sugars (9 mg g) as compared to other plants. Thus, the factors (temperature, pH, substrate concentration, and enzyme units) affecting its saccharification were optimized using central composite design. This statistical model predicted 49.8 mg g of reducing sugars that was comparable to the experimental value (40 mg g). Scanning electron microscopy and Fourier-transform infrared spectroscopy showed significant structural changes after pretreatment and saccharification. Therefore, halophytes growing in saline, arid, and semi-arid regions can be promising alternative sources for bioenergy production.
PubMed: 34616380
DOI: 10.3389/fmicb.2021.714940 -
Frontiers in Nutrition 2022Probiotics are a potential preventive strategy for obesity. However, with discrete efficacy and limited species of probiotics, there is a demand for novel strains with...
SCOPE
Probiotics are a potential preventive strategy for obesity. However, with discrete efficacy and limited species of probiotics, there is a demand for novel strains with excellent anti-obesity properties. This study aimed to investigate the effects of Brevibacillus laterosporus BL1 on preventing obesity in high-fat diet (HFD)-fed mice.
METHODS AND RESULTS
C57BL/6 male mice were randomly assigned to four groups ( = 10) and fed a control diet, HFD, HFD plus BL1, and HFD plus supernatant of BL1, respectively for 8 weeks. The results showed that prophylactic BL1 treatment reduced body weight gain by 41.26% in comparison to the HFD group, and this difference was accompanied by a reduction in body fat mass and the weight of inguinal white adipose tissues and epididymal white adipose tissue (-33.39%, -39.07%, and -43.75%, respectively). Moreover, the BL1-mediated improvements in lipid profile, insulin resistance, and chronic inflammation were associated with the regulation of gene expression related to lipid metabolism and enhancement of brown adipose tissue thermogenesis. Particularly, BL1 intervention significantly improved HFD-induced gut flora dysbiosis, as evidenced by a reverse in the relative abundance of Bacillota and Bacteroidota, as well as an increase in the relative abundance of bacteria that produce short-chain fatty acids (SCFAs), which in turn increased SCFAs levels.
CONCLUSION
Our findings found for the first time that BL1 may be a promising probiotic for prevention of obesity associated with the regulation of gut microbiota.
PubMed: 36505236
DOI: 10.3389/fnut.2022.1050025 -
Frontiers in Microbiology 2021is the causative agent of American Foulbrood (AFB), the most destructive bacterial infection in honeybees. Even antibiotic-sensitive strains of can produce recurrent...
is the causative agent of American Foulbrood (AFB), the most destructive bacterial infection in honeybees. Even antibiotic-sensitive strains of can produce recurrent AFB months to weeks post-antibiotic treatment due to the survival of bacterial spores. Recently, phages that infect have been shown to effectively combat AFB in the field. Here, we present evidence that phages not only bind to vegetative but also bind to spores. Spore binding was observed in the results of three specific experiments: (1) bacteria counted by flow cytometry generated quantitative data of FITC-labeled phages that were bound to vegetative bacteria as well as those bound to spores, (2) electron microscopy captured images of phages bound to the surface of spores in both horizontal and vertical positions, and (3) phages incubated with spores bound to the spores and created plaques in vegetative bacteria under conditions not conducive to spore activation, indicating that binding to spores is reversible and that the phages are still active. Identification of phages with reversible spore-binding capability for use in phage therapy may improve treatment of sporulating bacterial infections.
PubMed: 33574806
DOI: 10.3389/fmicb.2021.588035 -
Scientific Reports May 2023Echinomycin is a natural product DNA bisintercalator antibiotic. The echinomycin biosynthetic gene cluster in Streptomyces lasalocidi includes a gene encoding the...
Echinomycin is a natural product DNA bisintercalator antibiotic. The echinomycin biosynthetic gene cluster in Streptomyces lasalocidi includes a gene encoding the self-resistance protein Ecm16. Here, we present the 2.0 Å resolution crystal structure of Ecm16 bound to adenosine diphosphate. The structure of Ecm16 closely resembles that of UvrA, the DNA damage sensor component of the prokaryotic nucleotide excision repair system, but Ecm16 lacks the UvrB-binding domain and its associated zinc-binding module found in UvrA. Mutagenesis study revealed that the insertion domain of Ecm16 is required for DNA binding. Furthermore, the specific amino acid sequence of the insertion domain allows Ecm16 to distinguish echinomycin-bound DNA from normal DNA and link substrate binding to ATP hydrolysis activity. Expression of ecm16 in the heterologous host Brevibacillus choshinensis conferred resistance against echinomycin and other quinomycin antibiotics, including thiocoraline, quinaldopeptin, and sandramycin. Our study provides new insight into how the producers of DNA bisintercalator antibiotics fend off the toxic compounds that they produce.
Topics: Echinomycin; Adenosine Triphosphatases; DNA; Anti-Bacterial Agents; Streptomyces
PubMed: 37198233
DOI: 10.1038/s41598-023-34437-9 -
Applied and Environmental Microbiology Nov 2022Microbial Vpr-like proteases are extracellular multidomain subtilases with diverse functions and can form oligomers, but their maturation and oligomerization mechanisms...
Auto- and Hetero-Catalytic Processing of the N-Terminal Propeptide Promotes the C-Terminal Fibronectin Type III Domain-Mediated Dimerization of a Thermostable Vpr-like Protease.
Microbial Vpr-like proteases are extracellular multidomain subtilases with diverse functions and can form oligomers, but their maturation and oligomerization mechanisms remain to be elucidated. Here, we report a novel Vpr-like protease (BTV) from thermophilic bacterium sp. WF146. The BTV precursor comprises a signal peptide, an N-terminal propeptide, a subtilisin-like catalytic domain with an inserted protease-associated (PA) domain, two tandem fibronectin type III domains (Fn1 and Fn2), and a C-terminal propeptide. The BTV proform (pro-BTV) could be autoprocessed into the mature form (mBTV) via two intermediates lacking the N- or C-terminal propeptide, respectively, and the C-terminal propeptide delays the autocatalytic maturation of the enzyme. By comparison, pro-BTV is more efficiently processed into mBTV by protease TSS from strain WF146. Purified mBTV is a Ca-dependent thermostable protease, showing optimal activity at 60°C and retaining more than 60% of activity after incubation at 60°C for 8 h. The PA domain is important for enzyme stability and contributes to the substrate specificity of BTV by restricting the access of protein substrates to the active site. The proform and mature form of BTV exist as a monomer and a homodimer, respectively, and the dimerization is mediated by the Fn1 and Fn2 domains. The N-terminal propeptide of BTV not only acts as intramolecular chaperone and enzymatic inhibitor but also inhibits the homodimerization of the enzyme. The removal of the N-terminal propeptide leads to a structural adjustment of the enzyme and thus promotes enzyme dimerization. Vpr-like proteases are widely distributed in bacteria and fungi and are involved in processing lantibiotics, degrading collagen, keratin, and fibrin, and pathogenesis of microbes. The dissection of the roles of individual domains in enzyme maturation and oligomerization is crucial for understanding the action mechanisms of these multidomain proteases. Our results demonstrate that hetero-catalytic maturation of the extracellular Vpr-like protease BTV of sp. WF146 is more efficient than autocatalytic maturation of the enzyme. Moreover, we found that the C-terminal tandem fibronectin type III domains rather than the PA domain mediate the dimerization of mature BTV, while the N-terminal propeptide inhibits the dimerization of the BTV proform. This study provides new insight into the activation and oligomerization mechanisms of Vpr-like proteases.
Topics: Peptide Hydrolases; Fibronectin Type III Domain; Dimerization; Endopeptidases; Subtilisin
PubMed: 36250702
DOI: 10.1128/aem.01503-22 -
Frontiers in Microbiology 2022is a popular sticky fermented soybean food of the Eastern Himalayan regions of North East India, east Nepal, and south Bhutan. We hypothesized that some dominant...
is a popular sticky fermented soybean food of the Eastern Himalayan regions of North East India, east Nepal, and south Bhutan. We hypothesized that some dominant bacteria in may contribute to the formation of targeted and non-targeted metabolites for health benefits; hence, we studied the microbiome-metabolite mining of . A total of 1,394,094,912 bp with an average of 464,698,304 ± 120,720,392 bp was generated from metagenome, which resulted in the identification of 47 phyla, 331 families, 709 genera, and 1,560 species. Bacteria (97.78%) were the most abundant domain with the remaining domains of viruses, eukaryote, and archaea. (93.36%) was the most abundant phylum with 280 species of , among which was the most dominant species in followed by , , , , , , , and . Predictive metabolic pathways revealed the abundance of genes associated with metabolism (60.66%), resulting in 216 sub-pathways. A total of 361 metabolites were identified by metabolomic analysis (liquid chromatography-mass spectrophotometry, LC-MS). The presence of metabolites, such as chrysin, swainsonine, and 3-hydroxy-L-kynurenine (anticancer activity) and benzimidazole (antimicrobial, anticancer, and anti-HIV activities), and compounds with immunomodulatory effects in supports its therapeutic potential. The correlation between the abundant species of and primary and secondary metabolites was constructed with a bivariate result. This study proves that spp. contribute to the formation of many targeted and untargeted metabolites in for health-promoting benefits.
PubMed: 35572705
DOI: 10.3389/fmicb.2022.868383 -
International Journal of Environmental... Dec 2022To explore the mechanism by which the plant growth-promoting bacterium sp. SR-9 improves sweet sorghum tolerance and enriches soil cadmium (Cd) under pot conditions,...
To explore the mechanism by which the plant growth-promoting bacterium sp. SR-9 improves sweet sorghum tolerance and enriches soil cadmium (Cd) under pot conditions, the effect of strain SR-9 inoculation on the microbial community of sorghum rhizosphere soil was analyzed by metagenomics. Gene expression in sweet sorghum roots was analyzed using transcriptomics. The results showed that strain SR-9 promoted the growth of sweet sorghum and improved the absorption and enrichment of Cd in the plants. Compared with the uninoculated treatment, the aboveground part and root dry weight in strain SR-9 inoculated with sorghum increased by 21.09% and 17.37%, respectively, and the accumulation of Cd increased by 135% and 53.41%, respectively. High-throughput sequencing showed that strain SR-9 inoculation altered the rhizosphere bacterial community, significantly increasing the relative abundance of Actinobacteria and Firmicutes. Metagenomic analysis showed that after inoculation with strain SR-9, the abundance of genes involved in amino acid transport metabolism, energy generation and conversion, and carbohydrate transport metabolism increased. KEGG functional classification showed that inoculation with strain SR-9 increased the abundance of genes involved in soil microbial metabolic pathways in the rhizosphere soil of sweet sorghum and the activity of soil bacteria. Transcriptome analysis identified 198 upregulated differentially expressed genes in sweet sorghum inoculated with strain SR-9, including those involved in genetic information processing, biological system, metabolism, environmental information processing, cellular process, and human disease. Most of the annotated differentially expressed genes were enriched in the metabolic category and were related to pathways such as signal transduction, carbohydrate metabolism, amino acid metabolism, and biosynthesis of other secondary metabolites. This study showed that plant growth-promoting bacteria can alter the rhizosphere bacterial community composition, increasing the activity of soil bacteria and upregulating gene expression in sweet sorghum roots. The findings enhance our understanding of the microbiological and botanical mechanisms by which plant growth-promoting bacterial inoculation improves the remediation of heavy metals by sorghum.
Topics: Humans; Cadmium; Sorghum; Soil Pollutants; Brevibacillus; Soil; Soil Microbiology; Gene Expression Profiling; Amino Acids; Plant Roots; Biodegradation, Environmental
PubMed: 36498382
DOI: 10.3390/ijerph192316309 -
Cells Apr 2021Microbial endophytes organize symbiotic relationships with the host plant, and their excretions contain diverse plant beneficial matter such as phytohormones and... (Comparative Study)
Comparative Study
Microbial endophytes organize symbiotic relationships with the host plant, and their excretions contain diverse plant beneficial matter such as phytohormones and bioactive compounds. In the present investigation, six bacterial and four fungal strains were isolated from the common bean ( L.) root plant, identified using molecular techniques, and their growth-promoting properties were reviewed. All microbial isolates showed varying activities to produce indole-3-acetic acid (IAA) and different hydrolytic enzymes such as amylase, cellulase, protease, pectinase, and xylanase. Six bacterial endophytic isolates displayed phosphate-solubilizing capacity and ammonia production. We conducted a field experiment to evaluate the promotion activity of the metabolites of the most potent endophytic bacterial ( PB2 and PB5) and fungal ( PF2 and, PF3) strains in comparison to two exogenously applied hormone, IAA, and benzyl adenine (BA), on the growth and biochemical characteristics of the L. Interestingly, our investigations showed that bacterial and fungal endophytic metabolites surpassed the exogenously applied hormones in increasing the plant biomass, photosynthetic pigments, carbohydrate and protein contents, antioxidant enzyme activity, endogenous hormones and yield traits. Our findings illustrate that the endophyte (PB5) provides high potential as a stimulator for the growth and productivity of common bean plants.
Topics: Adenine; Biomass; Brevibacillus; Crop Production; Endophytes; Indoleacetic Acids; Phaseolus; Photosynthesis; Plant Growth Regulators
PubMed: 33946942
DOI: 10.3390/cells10051059 -
Applied and Environmental Microbiology Nov 2018Daqu is a spontaneous solid-state cereal fermentation used as saccharification and starter culture in Chinese vinegar and liquor production. The evolution of microbiota...
Daqu is a spontaneous solid-state cereal fermentation used as saccharification and starter culture in Chinese vinegar and liquor production. The evolution of microbiota in this spontaneous fermentation is controlled by the temperature profile, which reaches temperatures from 50 to 65°C for several days. Despite these high temperatures, mesophilic (including ) and bacilli are present throughout Daqu fermentation. This study aimed to determine whether Daqu spontaneous solid-state fermentation selects for heat-resistant variants of these organisms. Heat resistance in is mediated by the locus of heat resistance (LHR). One LHR-positive strain of was identified in Daqu, and it exhibited higher heat resistance than the LHR-negative isolated from malted oats. Heat resistance in endospores is mediated by the operon. Out of 10 Daqu isolates of the species , , , , and , 5 did not contain , 3 contained one copy, and 2 contained two copies. The presence and copy number of the operon increased the resistance of spores to treatment with 110°C. To confirm the selection of LHR- and -positive strains during Daqu fermentation, the copy numbers of these genetic elements in Daqu samples were quantified by quantitative PCR (qPCR). The abundance of LHR and the operon in community DNA relative to that of total bacterial 16S rRNA genes increased 3-fold and 5-fold, respectively, during processing. In conclusion, culture-dependent and culture-independent analyses suggest that Daqu fermentation selects for heat-resistant and bacilli. Daqu fermentations select for mobile genetic elements conferring heat resistance in and bacilli. The locus of heat resistance (LHR), a genomic island conferring heat resistance in , and the operon, conferring heat resistance on bacterial endospores, were enriched 3- to 5-fold during Daqu fermentation and maturation. It is therefore remarkable that the LHR and the operon are accumulated in the same food fermentation. The presence of heat-resistant spp. and spp. in Daqu is not of concern for food safety; however, both genomic islands are mobile and transferable to pathogenic bacteria or toxin-producing bacteria by horizontal gene transfer. The identification of the LHR and the operon as indicators of fitness of and bacilli in Daqu fermentation provides insights into environmental sources of heat-resistant organisms that may contaminate the food supply.
Topics: Bacillus; Enterobacteriaceae; Fermentation; Food Microbiology; Genomic Islands; Hot Temperature; Operon; Spores, Bacterial; Wine
PubMed: 30120119
DOI: 10.1128/AEM.01483-18 -
Microorganisms Mar 2022Field experiments testing the effect of phosphate-solubilizing rhizobacteria (PSRB) should consider the cropping history and the method used to inoculate the strains. We...
Field experiments testing the effect of phosphate-solubilizing rhizobacteria (PSRB) should consider the cropping history and the method used to inoculate the strains. We evaluated the hypothesis that PSRB previously isolated from soybean seedlings could be effective in promoting growth in this oilseed crop in soils with different cultivation periods. We also evaluated whether this growth promotion could be influenced by cultivation histories or the inoculation method (via seeds or soil). Thus, we conducted an experiment in five fields cultivating during two seasons (2019/2020 and 2020/2021), to test the effectiveness of PSRB (SAF9- sp., SAF11- sp., and SAC36-) compared with results observed for the inoculant BiomaPhos (mix of and ). The present study was based on the evaluation of vegetative growth, nutritional and yield parameters, and microbial biomass carbon (MBC). PSRB were more effective than, or showed similar effectiveness to, BiomaPhos for most of the evaluated vegetative, nutritional, and yield characteristics. In the fields tested in the summer 2019/2020 crop, SAC36 and SAF9 strains stood out as growth promoters, whereas in the 2020/2021 crop, SAF11, SAC36, and BiomaPhos were notable. There did not seem to be a direct relationship between long histories of soybean cultivation as a monoculture and low yield in the field. However, yield seems to be associated with soil nutritional characters such as Ca, Mg, K, P, cation exchange capacity, and organic matter levels. PSRB inoculation positively affected nodulation (NN) and nodule dry mass (NDM) in the evaluated fields in the 2019/2020 crop, and the aerial part dry mass (APDM), NN, NDM, yield, and MBC of the evaluated fields in the 2020/2021 crop. In contrast, the inoculation method was observed to have a strong effect on APDM, NN, root dry mass, and MBC, as the plants inoculated via seed showed higher mean values than those in the plants inoculated via soil. This study demonstrated the growth-promoting potential of new phosphate-solubilizing strains, which may eventually be incorporated by the biostimulants market to freely compete with BiomaPhos.
PubMed: 35456743
DOI: 10.3390/microorganisms10040691