The development of biotechnological lactic acid production has attracted attention to the potential production of an optically pure isomer of lactic acid, although the relationship between fermentation and the biosynthesis of highly optically pure D-lactic acid remains poorly understood. Sporolactobacillus terrae SBT-1 is an excellent D-lactic acid producer that depends on cultivation conditions. Herein, three enzymes responsible for synthesizing optically pure D-lactic acid, including D-lactate dehydrogenase (D-LDH; encoded by ldhDs), L-lactate dehydrogenase (L-LDH; encoded by ldhLs), and lactate racemase (Lar; encoded by larA), were quantified under different organic nitrogen sources and concentration to study the relationship between fermentation conditions and synthesis pathway of optically pure lactic acid. Different organic nitrogen sources and concentrations significantly affected the quantity and quality of D-lactic acid produced by strain SBT-1 as well as the synthetic optically pure lactic acid pathway. Yeast extract is a preferred organic nitrogen source for achieving high catalytic efficiency of D-lactate dehydrogenase and increasing the transcription level of ldhA2, indicating that this enzyme plays a major role in D-lactic acid formation in S. terrae SBT-1. Furthermore, lactate racemization activity could be regulated by the presence of D-lactic acid. The results of this study suggest that specific nutrient requirements are necessary to achieve a stable and highly productive fermentation process for the D-lactic acid of an individual strain.

The scarcity of soil nutrient availability under cold conditions of Himalayan regions needs a sustainable approach for better crop yields. The cold-adapted bacteria, Exiguobacterium sibiricum K1, with the potential to produce several plant growth-promoting (PGP) attributes, nitrogen fixation, indole acetic acid production, phosphate and potassium solubilization at 10 °C can provide an opportunity to promote crop yield improvement in an eco-friendly way under cold conditions. The bacterium also exhibited biocontrol activity against two phytopathogens and produced siderophore (53.0 ± 0.5 % psu). The strain\'s PGP properties were investigated using a spinach-based bioassay under controlled conditions. The bacterized seeds showed a notable increase in germination rate (23.2 %), shoot length (65.3 %), root length (56.6 %), leaf area (73.7 %), number of leaflets (65.2 %), and dry matter (65.2 %). Additionally, the leaf analysis indicated elevated chlorophyll pigments, i.e., chlorophyll a (55.5 %), chlorophyll b (42.8 %), carotenoids (35.2 %), percentage radical scavenging activity (47.4 %), and leaf nutrient uptake such as nitrogen (23.4 %), calcium (60.8 %), potassium (62.3 %), and magnesium (28.9 %). Moreover, the whole-genome sequencing and genome mining endorsed various biofertilisation-related genes, including genes for potassium and phosphate solubilization, iron and nitrogen acquisition, carbon dioxide fixation, and biocontrol ability of Exiguobacterium sibiricum K1. Overall, this study highlights the role of Exiguobacterium sibiricum K1 as a potential bioinoculant for improving crop yield under cold environments.

Major challenge in biorefineries is the use of all lignocellulosic components, particularly lignins. In this study, Thermobacillus xylanilyliticus grew on kraft lignin, steam-exploded and native wheat straws produced different sets of phenoloxidases and xylanases, according to the substrate. After growth, limited lignin structural modifications, mainly accompanied by a decrease in phenolic acids was observed by Nuclear Magnetic Resonance spectroscopy. The depletion of p-coumaric acid, vanillin and p-hydroxybenzaldehyde combined to vanillin production in the culture media indicated that the bacterium can transform some phenolic compounds. Proteomic approaches allowed the identification of 29 to 33 different hemicellulases according to the substrates. Twenty oxidoreductases were differentially expressed between kraft lignin and steam-exploded wheat straw. These oxidoreductases may be involved in lignin and aromatic compound utilization and detoxification. This study highlights the potential value of Thermobacillus xylanilyticus and its enzymes in the simultaneous valorization of hemicellulose and phenolic compounds from lignocelluloses.

The traditional way of dealing with plant diseases has been the use of chemical products, but these harm the environment and are incompatible with the global effort for sustainable development. The use of Bacillus and related species in the biological control of plant diseases is a trend in green agriculture. Many studies report the positive effect of these bacteria, but a synthesis is still necessary. So, the objective of this work is to perform a meta-analysis of Bacillus biocontrol potential and identify factors that drive its efficacy. Data were compiled from articles published in journals listed in two of the main scientific databases between 2000 and 2021. Among 6159 articles retrieved, 399 research papers met the inclusion criteria for a systematic review. Overall, Bacilli biocontrol agents reduced disease by 60% compared to control groups. Furthermore, experimental tests with higher concentrations show a strong protective effect, unlike low and single concentration essays. Biocontrol efficacy also increased when used as a protective inoculation rather than therapeutic inoculation. Inoculation directly in the fruit has a greater effect than soil drenching. The size of the effect of Bacillus-based commercial products is lower than the newly tested strains. The findings presented in this study confirm the power of Bacillus-based bioinoculants and provide valuable guidance for practitioners, researchers, and policymakers seeking effective and sustainable solutions in plant disease management.

The microbial fermentation of food has emerged as an efficient means to eliminate pesticide residues in agricultural products; however, the specific degradation characteristics and mechanisms remain unclear. In this study, a Gram-positive bacterium, Aneurinibacillus aneurinilyticus D-21, isolated from fermented Pixian Douban samples exhibited the capability to degrade 45 mg/L of cyfluthrin with an efficiency of 90.37%. Product analysis unveiled a novel cyfluthrin degradation pathway, involving the removal of the cyanide group and ammoniation of the ester bond into an amide. Whole genome analysis discovered the enzymes linked to cyfluthrin degradation, including nitrilase, esterase, carbon-nitrogen ligases, and enzymes associated with aromatic degradation. Additionally, metabolome analysis identified 140 benzenoids distributed across various aromatic metabolic pathways, further substantiating D-21\'s catabolic capability toward aromatics. This study underscores the exceptional pyrethroid degradation prowess of A. aneurinilyticus D-21, positioning it as a promising candidate for the biotreatment of pesticide residues in food systems.

The purpose of the current study was to explore root endophytes- Priestia megaterium T3 and Bacillus cereus T4 from Moringa olefiera for the suppression of leaf spot disease in tomato plants challenged with Xanthomonas vesicatoria. Both strains had plant growth-stimulating characteristics including auxin production, solubilization of inorganic phosphate and zinc complexes, and production of ammonia, siderophore, as well as hydrolytic enzymes. An agar well diffusion and fluorescence viability assay have validated the antibacterial effect of the cell-free culture supernatant of strains T3 and T4. Liquid chromatography-mass spectrometry (LC-MS) profiling has identified the secondary metabolites in the cell-free supernatant of strains T3 and T4. The bio-priming of tomato seeds with a consortium of T3 and T4 strains has significantly declined ethylene (by 0.61-fold) and hydrogen peroxide (H2O2, 0.64-fold) concentration thus, maintaining a lower content of ROS-induced malondialdehyde (MDA, 0.91-fold) as compared to control counterparts. Consequently, the leaf spot disease severity was reduced by ∼70% in consortium-treated tomato plants in contrast to their pathogen-challenged control. The consortia (T3+T4) treatment has facilitated induced systemic resistance by enhancing enzymatic activities of phenylalanine ammonia-lyase (PAL), peroxidase (PO), polyphenol oxidase (PPO), catalase (CAT), and ascorbate oxidase (AO) to detoxify the excessive Xanthomonas-induced ROS accumulation in tomato plants. Conclusively, bacterial endophytes modulate X. vesicatoria-induced ROS response and ethylene levels in tomato plants. The current findings indicate that plant growth-promoting endophytic bacterial strains hold the potential to sustainably enhance plant growth and suppress bacterial leaf spot disease in tomato plants.

Hyphantria cunea Drury (Lepidoptera: Erebidae) is a quarantine pest in China that can cause damage to hundreds of plants. As biological control agents, Nuclear Polyhedrosis Virus (NPV) and Bacillus thuringiensis Berliner (Bacillales: Bacillaceae) (Bt) are commonly used to inhibit the prevalence of H. cunea. To investigate the role of midgut bacteria in the infection of NPV and Bt in H. cunea, we performed a series of tests, including isolating the dominant culturable bacteria in the midgut, eliminating intestinal bacteria, and respectively inoculating the dominant strains with NPV and Bt for bioassay. Two dominant bacteria, Klebsiella oxytoca Lautrop (Enterobacterales: Enterobacteriaceae) and Enterococcus mundtii Collins (Lactobacillales: Enterococcaceae), in the midgut of H. cunea were identified, and a strain of H. cunea larvae without intestinal bacteria was successfully established. In the bioassays of entomopathogen infection, K. oxytoca showed significant synergistic effects with both NPV and Bt on the death of H. cunea. In contrast, E. mundtii played antagonistic effects. This phenomenon may be attributed to the differences in the physico-chemical properties of the two gut bacteria and the alkaline environment required for NPV and Bt to infect the host. It is worth noting that the enhanced insecticidal activity of K. oxytoca on NPV and Bt provides a reference for future biological control of H. cunea by intestinal bacteria.

The beetle Anthonomus grandis Boheman, 1843, is the main cotton pest, causing enormous losses in cotton. The breeding of genetically modified plants with A. grandis resistance is seen as an important control strategy. However, the identification of molecules with high toxicity to this insect remains a challenge. The susceptibility of A. grandis larvae to proteins (Cry1Ba, Cry7Ab, and Mpp23Aa/Xpp37Aa) from Bacillus thuringiensis Berliner, 1915, with toxicity reported against Coleopteran, has been evaluated. The ingestion of different protein concentrations (which were incorporated into an artificial diet) by the larvae was tested in the laboratory, and mortality was evaluated after one week. All Cry proteins tested exhibited higher toxicity than that the untreated artificial diet. These Cry proteins showed similar results to the control Cry1Ac, with low toxicity to A. grandis, since it killed less than 50% of larvae, even at the highest concentration applied (100 μg·g-1). Mpp/Xpp proteins provided the highest toxicity with a 0.18 μg·g-1 value for the 50% lethal concentration. Importantly, this parameter is the lowest ever reported for this insect species tested with B. thuringiensis proteins. This result highlights the potential of Mpp23Aa/Xpp37Aa for the development of a biotechnological tool aiming at the field control of A. grandis.

Sigma factor B (SigB) is the central regulator of the general stress response in Bacillus subtilis and regulates a group of genes in response to various stressors, known as the SigB regulon members. Genes that are directly regulated by SigB contain a promotor binding motif (PBM) with a previously identified consensus sequence.
In this study, refined SigB PBMs were derived and different spacer compositions and lengths (N12-N17) were taken into account. These were used to identify putative SigB-regulated genes in the B. subtilis genome, revealing 255 genes: 99 had been described in the literature and 156 genes were newly identified, increasing the number of SigB putative regulon members (with and without a SigB PBM) to > 500 in B. subtilis. The 255 genes were assigned to five categories (I-V) based on their similarity to the original SigB consensus sequences. The functionalities of selected representatives per category were assessed using promoter-reporter fusions in wt and ΔsigB mutants upon exposure to heat, ethanol, and salt stress. The activity of the PrsbV (I) positive control was induced upon exposure to all three stressors. PytoQ (II) showed SigB-dependent activity only upon exposure to ethanol, whereas PpucI (II) with a N17 spacer and PylaL (III) with a N16 spacer showed mild induction regardless of heat/ethanol/salt stress. PywzA (III) and PyaaI (IV) displayed ethanol-specific SigB-dependent activities despite a lower-level conserved - 10 binding motif. PgtaB (V) was SigB-induced under ethanol and salt stress while lacking a conserved - 10 binding region. The activities of PygaO and PykaA (III) did not show evident changes under the conditions tested despite having a SigB PBM that highly resembled the consensus. The identified extended SigB regulon candidates in B. subtilis are mainly involved in coping with stress but are also engaged in other cellular processes. Orthologs of SigB regulon candidates with SigB PBMs were identified in other Bacillales genomes, but not all showed a SigB PBM. Additionally, genes involved in the integration of stress signals to activate SigB were predicted in these genomes, indicating that SigB signaling and regulon genes are species-specific.
The entire SigB regulatory network is sophisticated and not yet fully understood even for the well-characterized organism B. subtilis 168. Knowledge and information gained in this study can be used in further SigB studies to uncover a complete picture of the role of SigB in B. subtilis and other species.

For a long time, the genus Bacillus has been known and considered among the most applicable genera in several fields. Recent taxonomical developments resulted in the identification of more species in Bacillus-related genera, particularly in the order Bacillales (earlier heterotypic synonym: Caryophanales), with potential application for biotechnological and industrial purposes such as biofuels, bioactive agents, biopolymers, and enzymes. Therefore, a thorough understanding of the taxonomy, growth requirements and physiology, genomics, and metabolic pathways in the highly diverse bacterial order, Bacillales, will facilitate a more robust designing and sustainable production of strain lines relevant to a circular economy. This paper is focused principally on less-known genera and their potential in the order Bacillales for promising applications in the industry and addresses the taxonomical complexities of this order. Moreover, it emphasizes the biotechnological usage of some engineered strains of the order Bacillales. The elucidation of novel taxa, their metabolic pathways, and growth conditions would make it possible to drive industrial processes toward an upgraded functionality based on the microbial nature.