Comparative genomic and transcriptome analysis of Bacillus velezensis CL-4 fermented corn germ meal

Effects of biopreparations based on Bacillus and Trichoderma, combined with mineral and organic fertilization and a Pisum sativum L. forecrop on improving the tolerance of Maize plants to drought stress

The increased frequency of extreme weather phenomena, such as heat waves and drought, adversely affects the condition of plants. The need to strive for more sustainable methods of growing plants requires undertaking researches that focus on strengthening the immunity of plants using methods that have a positive impact on both crops and the natural environment. The aim of the study was to assess the effectiveness and compare the effects of selected microbiological preparations based on Bacillus bacteria and Trichoderma symbiotic fungi, combined with mineral (NPK) and organic fertilization (manure) and a Pisum sativum L. forecrop on improving the tolerance of maize plants to drought stress. The pot experiment was carried in 2023 as a two-factor experiment in three replicates. Physiological parameters were assessed based on measurements of photosynthetic efficiency (A - CO2 assimilation rate, E - Transpiration Rate, Gs - Stomatal Conductance) and chlorophyll content (CCI) and fluorescence (F0 - initial fluorescence, Fm - maximum fluorescence, Fv/Fm - maximum photochemical efficiency of PSII, Yield - quantum yield of the photochemical reaction in PSII, ETR - electron transport rate, NPQ - Non - Photo-chemical Quenching), as well as soil respiration (NCER- Net CO2 Exchange Rate, W flux- Net H2O Exchange Rate, Ce- Soil Respiration) and biometric measurements (dry mass of shoots and roots).The measurement of photosynthesis efficiency under drought stress clearly indicated the highest, significant effect caused by Trichoderma preparation with both fertilizers. In the control, CO2 assimilation was practically inhibited due to drought (98% drop), while in the plants in which the Trichoderma preparation was used together with half dose of NPK and manure, there was only a slight decrease (1% and 13% respectively). A greatest, significant improvement in the DM of roots under drought was noted in plants in which the Pisum forecrop was applied together with NPK and manure (230% and 168% respectively). Pisum forecrop and treatments with microbiological preparation containing Trichoderma, make it possible to reduce the fertilization dose by at least half. This is particularly important in view of the global trend of increasing drought stress and efforts to improve soil quality.

Complete genome sequence and comparative analysis of Bacillus velezensis Lzh-5, a fungal antagonistic and plant growth-promoting strain

BACKGROUND

Plant diseases significantly and persistently impair product quality and yield across the globe. Employing antagonistic microorganisms represents an environmentally friendly and cost-effective approach to pathogen management. In this study, Bacillus velezensis Lzh-5 was explored to understand the molecular underpinnings of its antagonistic activity and plant growth-promoting properties.

RESULTS

We present the basic genomic profile of B. velezensis Lzh-5. Whole-genome analysis revealed that Lzh-5 possesses a 4,015,817 bp circular chromosome with a GC content of 46.0%, and an 8,933 bp circular plasmid with a GC content of 40.5%. A total of 3,998 genes were predicted, of which 3,881 (97.07%) are coding DNA sequences (CDSs). Through phylogenomic and comparative genomic analyses, strain Lzh-5 was confirmed as B. velezensis. The Lzh-5 genome harbors genes for cell wall-degrading enzymes. Additionally, 13 gene clusters responsible for secondary metabolite production were identified. Notably, a unique cluster (cluster 2) coding for an unknown compound was found exclusively in strain Lzh-5. Genes associated with plant growth enhancement, such as those involved in chemotaxis, motility, biofilm formation, phytohormone production, nitrogen fixation, phosphate solubilization, glycine betaine biosynthesis, and acetoin and 2,3-butanediol synthesis, were also identified.

CONCLUSION

The basic characteristics of strain Lzh-5 genome were delineated through whole-genome sequencing. Our analysis indicates that the Lzh-5 genome encompasses various genes that promote plant growth, induce systemic resistance, and antagonize pathogens. Compared to other strains, several unique gene clusters in Lzh-5 may contribute to the discovery of novel bioactive compounds and offer a broader antagonistic spectrum. This investigation elucidates the antifungal and plant growth-promoting mechanisms of B. velezensis Lzh-5 at a genetic level, providing a theoretical foundation for further application in agricultural production.

Effects of Bacillus velezensis fermentation on the composition, structure, physicochemical properties and in vitro hypoglycemic effects of highland barley dietary fiber

Dietary fiber in cereals is an important active substance and is believed to be beneficial to consumer health. To improve the physicochemical and functional properties of highland barley dietary fiber and the integrated utilization of highland barley, Bacillus velezensis submerged fermentation was used to treat highland barley. Soluble and insoluble dietary fibers (SDF and IDF) were isolated and their yield, proximate composition, monosaccharide compositions, physicochemical, structural and functional characteristics were investigated. The results showed that fermentation could significantly increase the SDF yield from 6.07 to 12.57 %. Fermentation changed the monosaccharide composition ratio and rendered SDF and IDF a looser and more porous structure. The crystallinity was also changed significantly. Fermentation improved the water retention capacity and swelling capacity of SDF, while decreased that of IDF. The glucose adsorption ability, glucose delayed dialysis ability, α-glucosidase and α-amylase inhibitory activities of highland barley SDF and IDF were all improved after fermentation, especially for SDF. These results indicated that fermentation is an efficient and environmentally friendly modification method and modified SDF can be utilized in the food processing industry, promoting the high-value application of highland barley dietary fiber.

Comparative Genomic Analysis of Bacillus velezensis BRI3 Reveals Genes Potentially Associated with Efficient Antagonism of Sclerotinia sclerotiorum (Lib.) de Bary

BACKGROUND/OBJECTIVES

Bacillus velezensis has recently received increased attention as a potential biological agent because of its broad-spectrum antagonistic capacity against harmful bacteria and fungi. This study aims to thoroughly analyze the genomic characteristics of B. velezensis BRI3, thereby providing theoretical groundwork for the agronomic utilization of this strain.

METHODS

In this work, we evaluated the beneficial traits of the newly isolated strain B. velezensis BRI3 via in vitro experiments, whole-genome sequencing, functional annotation, and comparative genomic analysis.

RESULTS

B. velezensis BRI3 exhibits broad-spectrum antifungal activity against various soilborne pathogens, displays inhibitory effects comparable to those of the type strain FZB42, and exhibits particularly effective antagonism against Sclerotinia sclerotiorum (Lib.) de Bary. Whole-genome sequencing and assembly revealed that the genome of BRI3 contains one chromosome and two plasmids, which carry a large amount of genetic information. Moreover, 13 biosynthetic gene clusters (BGCs) involved in the biosynthesis of secondary metabolites were predicted within the BRI3 genome. Among these, two unique BGCs (cluster 11 and cluster 13), which were not previously reported in the genomes of other strains and could potentially encode novel metabolic products, were identified. The results of the comparative genomic analysis demonstrated the genomic structural conservation and genetic homogeneity of BRI3.

CONCLUSIONS

The unique characteristics and genomic data provide insights into the potential application of BRI3 as a biocontrol and probiotic agent.

Current models in bacterial hemicellulase-encoding gene regulation

The discovery and characterization of bacterial carbohydrate-active enzymes is a fundamental component of biotechnology innovation, particularly for renewable fuels and chemicals; however, these studies have increasingly transitioned to exploring the complex regulation required for recalcitrant polysaccharide utilization. This pivot is largely due to the current need to engineer and optimize enzymes for maximal degradation in industrial or biomedical applications. Given the structural simplicity of a single cellulose polymer, and the relatively few enzyme classes required for complete bioconversion, the regulation of cellulases in bacteria has been thoroughly discussed in the literature. However, the diversity of hemicelluloses found in plant biomass and the multitude of carbohydrate-active enzymes required for their deconstruction has resulted in a less comprehensive understanding of bacterial hemicellulase-encoding gene regulation. Here we review the mechanisms of this process and common themes found in the transcriptomic response during plant biomass utilization. By comparing regulatory systems from both Gram-negative and Gram-positive bacteria, as well as drawing parallels to cellulase regulation, our goals are to highlight the shared and distinct features of bacterial hemicellulase-encoding gene regulation and provide a set of guiding questions to improve our understanding of bacterial lignocellulose utilization. KEY POINTS: • Canonical regulatory mechanisms for bacterial hemicellulase-encoding gene expression include hybrid two-component systems (HTCS), extracytoplasmic function (ECF)-σ/anti-σ systems, and carbon catabolite repression (CCR). • Current transcriptomic approaches are increasingly being used to identify hemicellulase-encoding gene regulatory patterns coupled with computational predictions for transcriptional regulators. • Future work should emphasize genetic approaches to improve systems biology tools available for model bacterial systems and emerging microbes with biotechnology potential. Specifically, optimization of Gram-positive systems will require integration of degradative and fermentative capabilities, while optimization of Gram-negative systems will require bolstering the potency of lignocellulolytic capabilities.

Introduction of Cellulolytic Bacterium Bacillus velezensis Z2.6 and Its Cellulase Production Optimization

Enzyme-production microorganisms typically occupy a dominant position in composting, where cellulolytic microorganisms actively engage in the breakdown of lignocellulose. Exploring strains with high yields of cellulose-degrading enzymes holds substantial significance for the industrial production of related enzymes and the advancement of clean bioenergy. This study was inclined to screen cellulolytic bacteria, conduct genome analysis, mine cellulase-related genes, and optimize cellulase production. The potential carboxymethylcellulose-hydrolyzing bacterial strain Z2.6 was isolated from the maturation phase of pig manure-based compost with algae residuals as the feedstock and identified as Bacillus velezensis. In the draft genome of strain Z2.6, 31 related cellulolytic genes were annotated by the CAZy database, and further validation by cloning documented the existence of an endo-1,4-β-D-glucanase (EC 3.2.1.4) belonging to the GH5 family and a β-glucosidase (EC 3.2.1.21) belonging to the GH1 family, which are predominant types of cellulases. Through the exploration of ten factors in fermentation medium with Plackett-Burman and Box-Behnken design methodologies, maximum cellulase activity was predicted to reach 2.98 U/mL theoretically. The optimal conditions achieving this response were determined as 1.09% CMC-Na, 2.30% salinity, and 1.23% tryptone. Validation under these specified conditions yielded a cellulose activity of 3.02 U/mL, demonstrating a 3.43-fold degree of optimization. In conclusion, this comprehensive study underscored the significant capabilities of strain Z2.6 in lignocellulolytic saccharification and its potentialities for future in-depth exploration in biomass conversion.

Cellulase with Bacillus velezensis improves physicochemical characteristics, microbiota and metabolites of corn germ meal during two-stage co-fermentation

Corn germ meal (CGM) is one of the major byproducts of corn starch extraction. Although CGM has rich fiber content, it lacks good protein content and amino acid balance, and therefore cannot be fully utilized as animal feed. In this study, we investigated the processing effect of cellulase synergized with Bacillus velezensis on the nutritional value of pretreated CGM (PCGM) in two-stage solid-state fermentation (SSF). High-throughput sequencing technology was used to explore the dynamic changes in microbial diversity. The results showed that compared with four combinations of B. velezensis + Lactiplantibacillus plantarum (PCGM-BL), cellulase + L. plantarum (PCGM-CL),control group (PCGM-CK), and cellulase + B. velezensis + L. plantarum (PCGM-BCL), the fourth combination of PCGM-BCL significantly improved the nutritional characteristics of PCGM. After two-stage SSF (48 h), viable bacterial count and contents of crude protein (CP) and trichloroacetic acid-soluble protein (TCA-SP) all were increased in PCGM-BCL (p < 0.05), while the pH was reduced to 4.38 ± 0.02. In addition, compared with PCGM-BL, the cellulose degradation rate increased from 5.02 to 50.74%, increasing the amounts of short-chain fatty acids (216.61 ± 2.74 to 1727.55 ± 23.00 µg/g) and total amino acids (18.60 to 21.02%) in PCGM-BCL. Furthermore, high-throughput sequencing analysis revealed significant dynamic changes in microbial diversity. In the first stage of PCGM-BCL fermentation, Bacillus was the dominant genus (99.87%), which after 24 h of anaerobic fermentation changed to lactobacillus (37.45%). Kyoto Encylopaedia of Genes and Genomes (KEGG) metabolic pathway analysis revealed that the pathways related to the metabolism of carbohydrates, amino acids, cofactors, and vitamins accounted for more than 10% of the enriched pathways throughout the fermentation period. Concisely, we show that cellulase can effectively improve the nutritional value of PCGM when synergized with B. velezensis in two-stage SSF.

Whole-Genome Analysis of Termite-Derived Bacillus velezensis BV-10 and Its Application in King Grass Silage

Bacillus velezensis (B. velezensis) is a cellulose-degrading strain that has the potential as an additive in fermented feed. B. velezensis BV-10 was isolated and screened from the termite gut. We sequenced the whole genome of this new source of B. velezensis to reveal its potential for use in cellulose degradation. Whole-genome sequencing of B. velezensis BV-10 showed that it has a circular chromosome of 3929792 bp containing 3873 coding genes with a GC content of 45.51% and many genes related to cellulose, hemicellulose, and lignin degradation. King grass silage was inoculated with B. velezensis BV-10 and mixed with other feed additives to assess the effect of B. velezensis BV-10 on the fermentation quality of silage. Six treatment groups were established: the control, B. velezensis BV-10, molasses, cellulase, B. velezensis BV-10 plus molasses, and B. velezensis BV-10 plus cellulase groups. After 30 days of silage-fermentation testing, B. velezensis BV-10 was found to rapidly reduce the silage pH value and significantly reduce the acid-detergent fiber (ADF) content (p < 0.05). The addition of B. velezensis BV-10 plus molasses and cellulase in fermented feed significantly reduced the silage neutral-detergent fiber and ADF content and promoted organic-acid accumulation (p < 0.05). The above results demonstrate that B. velezensis BV-10 promotes the fermentation quality of silage and that this effect is greater when other silage-fermentation additives are included. In conclusion, genes involved in cellulose degradation in B. velezensis BV-10 were identified by whole-genome sequencing and further experiments explored the effects of B. velezensis BV-10 and different feed additives on the fermentation quality of king grass silage, revealing the potential of Bacillus velezensis as a new silage additive.

Analyzing Current Trends and Possible Strategies to Improve Sucrose Isomerases' Thermostability

Due to their ability to produce isomaltulose, sucrose isomerases are enzymes that have caught the attention of researchers and entrepreneurs since the 1950s. However, their low activity and stability at temperatures above 40 °C have been a bottleneck for their industrial application. Specifically, the instability of these enzymes has been a challenge when it comes to their use for the synthesis and manufacturing of chemicals on a practical scale. This is because industrial processes often require biocatalysts that can withstand harsh reaction conditions, like high temperatures. Since the 1980s, there have been significant advancements in the thermal stabilization engineering of enzymes. Based on the literature from the past few decades and the latest achievements in protein engineering, this article systematically describes the strategies used to enhance the thermal stability of sucrose isomerases. Additionally, from a theoretical perspective, we discuss other potential mechanisms that could be used for this purpose.