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Background and Aims Rhizosphere microorganisms play an important role in promoting plant growth and maintaining soil health. Bacillus altitudinis LZP02 (LZP02) is an efficient plant growth-promoting rhizobacterium that interacts closely with rice radicals. However, the mechanisms mediating the rhizosphere interactions of beneficial strains of microorganisms in native soil are mostly unclear. Methods This study analysed the rhizosphere-enriched taxonomic and functional properties of the rhizosphere-associated microbiome and determined how they were affected by LZP02 using metagenome sequencing and ITS sequencing after the inoculation of LZP02 in soil. And microorganisms from the rice rhizosphere were identified and cultivated using high-throughput sequencing. Results LZP02 stimulated some beneficial bacteria, such as Novosphingobium , Acidovorax , Sphingomonas , and Devosia , to the rhizosphere. The enrichment of functional attributes, nitrogen metabolism and bacterial chemotaxis demonstrated an increase in active microbe-microbe interactions in the rhizosphere. This study showed that LZP02 stimulated plant growth in three ways: (1) by increasing the relative abundance of most rhizosphere-enriched genus; (2) by increasing the relative abundance of the functional attributes involved in microbe-microbe interactions; and (3) by enriching functional components that are essential for plant fitness, such as nitrogen fixation and bacterial chemotaxis in the rhizosphere microbiome. Finally, inoculation of enriched single strains or synthetic consortia isolated from the radical-associated microbiome using high-throughput cultivation could improve plant growth. Conclusion This study proposes a new mechanism by which LZP02 influences the nitrogen metabolism of rhizosphere microorganisms and bacterial chemotaxis for rice growth by reshaping the rhizosphere microbiome.

Microbial succession and metabolic adjustment during cigar tobacco leaf (CTL) fermentation are key factors to improve the quality and flavor of CTLs. However, the interactions in the above processes remain to be further elucidated. inoculants were added to the CTLs, and metagenomics and metabolomics were used to analyze the effects of the inoculants on regulating microbial succession, metabolic shift, and aroma production during fermentation. The addition of the inoculants reinforced the CTL macromolecule transformation and facilitated the aroma production efficiently, and the total aroma production was increased by 43% compared with natural fermentation. The omics analysis showed that was a main contributor to fatty acid degradation, inositol phosphate metabolism, energy supply (oxidative phosphorylation), nutrient transport (ABC transporter and phosphotransferase system [PTS]), and aroma production (terpenoid backbone biosynthesis, phenylalanine metabolism, and degradation of aromatic compounds). Furthermore, was positively correlated with TCA cycle intermediates (citric acid, fumaric acid, and aconitic acid), cell wall components, peptidoglycan intermediates (GlcNAc-1-P and UDP-GlcNAc), and phytic acid degradation products (inositol). The characteristics collectively showed to be the most dominant in the microbial community at the genus level during microflora succession. The addition of the inoculants supplemented the nutritional components of the CTLs, enhanced the metabolic activity and diversity of bacteria such as , improved their competitive advantages in the microflora succession, and facilitated the richness of microbial communities. Additionally, a metabolic shift in nicotine degradation and NAD + anabolism from to in fermentation with inoculants was first observed. Meanwhile, the significantly correlative differential metabolites with and were a metabolic complement, thus forming a completely dynamic fermentation ecosystem. The results provided evidence for CTL fermentation optimization.

Bacillus strain UTK D1-0055 was isolated from a laboratory environment and appeared to have antilisterial activity. The genome was sequenced, the strain was identified as Bacillus altitudinis, and a high-quality complete annotated genome was produced. The taxonomy was evaluated for this and related Bacillus species (B. aerophilus, B. pumilus, B. safensis, B. stratosphericus, and B. xiamenensis) because the taxonomy is unclear and contains errors in public databases such as NCBI. The included strains grouped into seven clusters based on average nucleotide identity. Strains designated as B. aerophilus, B. altitudinis, and B. stratosphericus grouped together in the cluster containing the B. altitudinis type strain, suggesting that these three species should be considered a single species, B. altitudinis. The antimicrobial activity of UTK D1-0055 was evaluated against a panel of 15 Listeria strains (nine Listeria monocytogenes serotypes, Listeria innocua, and Listeria marthii), other foodborne pathogens (six Salmonella enterica serotypes and Escherichia coli), and three representative fungi (Saccharomyces cerevisiae, Botrytis cinerea, and Hyperdermium pulvinatum). Antibacterial activity was observed against all Listeria strains, but no antibacterial effects were found against the other tested bacterial and fungal strains. Biosynthetic gene clusters were identified in silico that may be related to the observed antibacterial activity, and these clusters included genes that putatively encode bacteriocins and nonribosomally synthesized peptides. The B. altitudinis strain identified in this investigation had a broad range of antilisterial activity, suggesting that it and other related strains may be useful for biocontrol in the food industry.

Microbial herbicides play a vital role in agricultural preservation, amid growing concerns over the ecological impact from extensive development and use of chemical herbicides. Utilizing beneficial microbial metabolites to combat weeds has become a significant focus of research. This study focused on isolating herbicidal active compounds from Bacillus altitudinis D30202 through activity-guided methods. First, the n -butanol extract ( n -BE) of B. altitudinis D30202 underwent fractionation using macroporous adsorption resin D101 and Sephadex LH-20, identifying Fr. F as the most potent segment against wild oats ( Avena fatua L.). Ultra-performance liquid chromatography − quadrupole time-of-flight mass spectrometry (UPLC − QTOF-MS) identified nine compounds in the active fraction Fr. F. Subsequently, three subfractions (Fr.F-1 to Fr.F-3) were derived from Fr.F via semi-preparative liquid chromatography, resulting in methyl indole-3-acetate (MeIAA) purification. MeIAA, functioning as an auxin analog, exhibited effects of indole-3-acetic acid (IAA) on wild oats’ growth, with a root length median inhibitory concentration of 81.06 µg/ml. Furthermore, we assessed MeIAA’s herbicidal impact on five weed species across diverse families and genera, providing a first-time analysis of MeIAA’s mechanism on wild oats. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed structural damage to leaves and roots post-MeIAA treatment. MeIAA treatment increased superoxide anion and hydrogen peroxide levels in wild oat roots, alongside with elevated peroxidase (POD) and superoxide dismutase (SOD) activity, chlorophyll-degrading enzymes (Chlase, MDACase), malondialdehyde (MDA) content, and relative conductivity in leaves. Conversely, it decreased catalase (CAT) activity and chlorophyll content. Therefore, this study provides a new material source and theoretical foundation for ecologically sustainable agricultural weed control.

Soybean Phytophthora root rot (PRR) caused by Phytophthora sojae is one of the most devastating diseases of soybean worldwide. This study was conducted to develop new effective biocontrol agents for the control of the disease and explore the action mechanism . Eleven antagonistic bacterial strains against P. sojae were isolated from the soybean field soil samples, and among the strains, BS-4 not only had the strongest inhibitory activity against P. sojae , but also had good inhibition to other four species of oomycetes in Phytophthora and eight fungal pathogens. Based on 16S rDNA sequence analysis and the physiological and biochemical properties, the strain BS-4 was identified as Bacillus altitudinis . Strain BS-4 culture filtrate had significant inhibitory effects on the pathogens, and the inhibition rates were stronger than those in the dual culture. BS-4 filtrate kept a high bioactivity to P. sojae at a high temperature, even at 121℃, and in the pH range of 5 to 12. The germination of zoospores and the formation of sexual organs were seriously affected by BS-4 filtrate. Furthermore, detached leaf assays and greenhouse experiments showed that BS-4 suspension and culture filtrate all had good disease control efficacy, and in the field experiment, BS-4 suspension reduced the disease index and increased the biomass of soybean shoots and roots, significantly ( P < 0.05), with control effect of 75.29% on PRR. It is suggested that B. altitudinis strain BS-4 is a novel potential biocontrol agent to control PRR, and will have a broad application prospect in PRR biocontrol.

Chicken egg shell and membrane were used as substrate for production of alkaline protease by Bacillus altitudinis GVC11. Maltose as additional carbon source enhanced enzyme production up to 13%. Addition of organic nitrogen sources like peptone and yeast extract increased enzyme production by 9% and 5%, respectively and inorganic nitrogen sources did not have any positive effect. The resultant protein hydrolyzate after fermentation was found to have essential amino acids such as leucine, phenyl alanine, isoleucine, lysine, valine, methionine, arginine in considerable quantities and minute concentrations of cysteine. The protein hydrolyzate was also found to have good antioxidant activity.

Lignin is a major by-product of pulp and paper industries, and is resistant to depolymerization due to its heterogeneous structure. Degradation of lignin can be achieved by the use of potential lignin-degrading bacteria. The current study was designed to evaluate the degradation efficiency of newly isolated Bacillus altitudinis SL7 from pulp and paper mill effluent. The degradation efficiency of B. altitudinis SL7 was determined by color reduction, lignin content, and ligninolytic activity from degradation medium supplemented with alkali lignin (3 g/L). B. altitudinis SL7 reduced color and lignin content by 26 and 44%, respectively, on the 5th day of incubation, as evident from the maximum laccase activity. Optimum degradation was observed at 40 °C and pH 8.0. FT-IR spectroscopy and GC-MS analysis confirmed lignin degradation by emergence of the new peaks and identification of low-molecular-weight compounds in treated samples. The identified compounds such as vanillin, 2-methyoxyhenol, 3-methyl phenol, oxalic acid and ferulic acid suggested the degradation of coniferyl and sinapyl groups of lignin. Degradation efficiency of B. altitudinis SL7 towards high lignin concentration under alkaline pH indicated the potential application of this isolate in biological treatment of the lignin-containing effluents.

The objective of this study was to evaluate the effect of feeding Bacillus altitudinis spores to sows and/or offspring on growth and health indicators. On day (D) 100 of gestation, twenty-four sows were selected and grouped as: control (CON), fed with a standard diet; and probiotic (PRO), fed the standard diet supplemented with B. altitudinis WIT588 spores from D100 of gestation until weaning. Offspring (n 144) from each of the two sow treatments were assigned to either a CON (no probiotic) or PRO (B. altitudinis-supplemented) treatment for 28 d post-weaning (pw), resulting in four treatment groups: (1) CON/CON, non-probiotic-supplemented sow/non-probiotic-supplemented piglet; (2) CON/PRO, non-probiotic-supplemented sow/probiotic-supplemented piglet; (3) PRO/CON, probiotic-supplemented sow/non-probiotic-supplemented piglet and (4) PRO/PRO, probiotic-supplemented sow/probiotic-supplemented piglet. B. altitudinis WIT588 was detected in the faeces of probiotic-supplemented sows and their piglets, and in the faeces and intestine of probiotic-supplemented piglets. Colostrum from PRO sows had higher total solids (P = 0·02), protein (P = 0·04) and true protein (P = 0·05), and lower lactose (P < 0·01) than colostrum from CON sows. Maternal treatment improved offspring feed conversion ratio at D0–14 pw (P < 0·001) and increased offspring body weight at D105 and D127 pw (P = 0·01), carcass weight (P = 0·05) and kill-out percentage (P < 0·01). It also increased small intestinal absorptive capacity and impacted the haematological profile of sows and progeny. There was little impact of pw treatment on any of the parameters measured. Overall, the lifetime growth benefits in the offspring of B. altitudinis-supplemented sows offer considerable economic advantages for pig producers in search of alternatives to in-feed antibiotics/zinc oxide.

Background Verticillium wilt, caused by the fungus Verticillium dahliae , is a soil-borne vascular fungal disease, which has caused great losses to cotton yield and quality worldwide. The strain KRS010 was isolated from the seed of Verticillium wilt-resistant Gossypium hirsutum cultivar “Zhongzhimian No. 2.” Results The strain KRS010 has a broad-spectrum antifungal activity to various pathogenic fungi as Verticillium dahliae , Botrytis cinerea , Fusarium spp., Colletotrichum spp., and Magnaporthe oryzae , of which the inhibition rate of V. dahliae mycelial growth was 73.97% and 84.39% respectively through confrontation test and volatile organic compounds (VOCs) treatments. The strain was identified as Bacillus altitudinis by phylogenetic analysis based on complete genome sequences, and the strain physio-biochemical characteristics were detected, including growth-promoting ability and active enzymes. Moreover, the control efficiency of KRS010 against Verticillium wilt of cotton was 93.59%. After treatment with KRS010 culture, the biomass of V. dahliae was reduced. The biomass of V. dahliae in the control group (Vd991 alone) was 30.76-folds higher than that in the treatment group (KRS010+Vd991). From a molecular biological aspect, KRS010 could trigger plant immunity by inducing systemic resistance (ISR) activated by salicylic acid (SA) and jasmonic acid (JA) signaling pathways. Its extracellular metabolites and VOCs inhibited the melanin biosynthesis of V. dahliae . In addition, KRS010 had been characterized as the ability to promote plant growth. Conclusions This study indicated that B. altitudinis KRS010 is a beneficial microbe with a potential for controlling Verticillium wilt of cotton, as well as promoting plant growth.

The rise of antimicrobial resistance poses a significant global health threat, necessitating urgent efforts to identify novel antimicrobial agents. In this study, we undertook a thorough screening of soil-derived bacterial isolates to identify candidates showing antimicrobial activity against Gram-positive bacteria. A highly active antagonistic isolate was initially identified as Bacillus altitudinis ECC22, being further subjected to whole genome sequencing. A bioinformatic analysis of the B. altitudinis ECC22 genome revealed the presence of two gene clusters responsible for synthesizing two circular bacteriocins: pumilarin and a novel circular bacteriocin named altitudin A, alongside a closticin 574-like bacteriocin (CLB) structural gene. The synthesis and antimicrobial activity of the bacteriocins, pumilarin and altitudin A, were evaluated and validated using an in vitro cell-free protein synthesis (IV-CFPS) protocol coupled to a split-intein-mediated ligation procedure, as well as through their in vivo production by recombinant E. coli cells. However, the IV-CFPS of CLB showed no antimicrobial activity against the bacterial indicators tested. The purification of the bacteriocins produced by B. altitudinis ECC22, and their evaluation by MALDI-TOF MS analysis and LC-MS/MS-derived targeted proteomics identification combined with massive peptide analysis, confirmed the production and circular conformation of pumilarin and altitudin A. Both bacteriocins exhibited a spectrum of activity primarily directed against other Bacillus spp. strains. Structural three-dimensional predictions revealed that pumilarin and altitudin A may adopt a circular conformation with five- and four-α-helices, respectively.