Biocontrol of rusted root rot in Panax ginseng by a combination of extracts from Bacillus amyloliquefaciens YY8 crude protein and Enterobacteriaceae YY115 ethyl acetate.

BACKGROUND: Rusted root rot is one of the most common root diseases in Panax ginseng, and Cylindrocarpon destructans is one of the main pathogenic fungus. The objective of this study was to screen and explore the extracts of biocontrol bacteria isolated from ginseng rhizosphere soil against Cylindrocarpon destructans. RESULTS: Bacterial strains Bacillus amyloliquefaciens YY8 and Enterobacteriacea YY115 were isolated and found to exhibit in vitro antifungal activity against C. destructans. A combination of crude protein extract from B. amyloliquefaciens YY8 and ethyl acetate extract from Enterobacteriacea YY115 in a 6:4 ratio exhibited the strongest antifungal activity against C. destructans. Measurements of electrical conductivity, protein content, and nucleic acid content in suspension cultures of C. destructans treated with a mixture extracts indicated that the extracts disrupted the cell membranes of rusted root rot mycelia, resulting in the leakage of electrolytes, proteins, and nucleic acids from the cells, and ultimately inhibiting the growth of C. destructans. The combined extracts suppressed the infection of ginseng roots discs by C. destructans effectively. CONCLUSION: The extracts obtained from the two bacterial strains effectively inhibited C. destructans in P. ginseng. It can provide scientific basis for the development of new biological control pesticides, reduce the use of chemical pesticides, and promote the sustainable development of agriculture.

Spore germination and lactic acid combined treatment: A new processing strategy for the shelf-life extension of instant wet noodles.

Bacillus amyloliquefaciens (BAM) was identified as the predominant spoilage bacteria in instant wet noodles (IWNs). The utilization of industrial acid treatment as a long shelf-life strategy resulted in reduced consumer acceptance due to the acidic taste of the products. This study proposed a processing strategy that integrated spore germination (SG) and lactic acid (LA) treatment to effectively reduce the spore survival rate and extend the shelf life of IWNs. L-histidine, d-glucose, and sodium chloride were highly efficient and safe germinants for BAM spores. In IWNs, compound germinants (1.0 % L-histidine, 0.5 % d-glucose, and 1.0 % sodium chloride) boosted the SG rate by 3.61 times. With synergistic LA treatment, the spore lethality increased by 34.41 % -41.68 %. Under the SG and reduced acid-heat conditions of pH 2.30-2.50, the mortality of spores could reach 92.00 %-93.17 %, which was 14.11 %-15.28 % higher than the industrial acid-heat condition of pH 2.10. DPA, ATP, and membrane potential showed that germinants reduced the spore membrane permeability and promoted the occurrence of spore membrane damage under acid-heat conditions. Moreover, this strategy significantly extended the shelf-life of IWNs by 3.00-5.50 times and controlled the pH ≥ 5.50. Additionally, it improved color, texture, and overall sensory evaluation. Accordingly, this strategy solved the contradiction between the long shelf-life of IWNs and the unacceptable acidification in industrial production.

Multiple Perspectives of Study on the Potential of Bacillus amyloliquefaciens JB20221020 for Alleviating Nutrient Stress in Lettuce.

Soil nutrient deficiency has become a key factor limiting crop growth. Plant growth-promoting rhizobacteria (PGPR) are vital in resisting abiotic stress. In this study, we investigated the effects of inoculation with Bacillus amyloliquefaciens JB20221020 on the physiology, biochemistry, rhizosphere microorganisms, and metabolism of lettuce under nutrient stress. Pot experiments showed that inoculation with B. amyloliquefaciens JB20221020 significantly promoted lettuce growth under nutrient deficiency. At the same time, the activities of the antioxidant enzymes superoxide dismutase, peroxidase, and catalase and the content of proline increased, and the content of Malondialdehyde decreased in the lettuce inoculated with B. amyloliquefaciens JB20221020. Inoculation with B. amyloliquefaciens JB20221020 altered the microbial community of the rhizosphere and increased the relative abundances of Myxococcales, Deltaproteobacteria, Proteobacteria, Devosia, and Verrucomicrobia. Inoculation also altered the rhizosphere metabolism under nutrient deficiency. The folate metabolism pathway was significantly enriched in the Kyoto Encyclopedia of Genes and Genomes enrichment analysis. This study explored the interaction between plants and microorganisms under nutrient deficiency, further explained the critical role of rhizosphere microorganisms in the process of plant nutrient stress, and provided a theoretical basis for the use of microorganisms to improve plant resistance.

Osmolyte-producing microbial biostimulants regulate the growth of Arachis hypogaea L. under drought stress.

Globally, drought stress poses a significant threat to crop productivity. Improving the drought tolerance of crops with microbial biostimulants is a sustainable strategy to meet a growing population's demands. This research aimed to elucidate microbial biostimulants' (Plant Growth Promoting Rhizobacteria) role in alleviating drought stress in oil-seed crops. In total, 15 bacterial isolates were selected for drought tolerance and screened for plant growth-promoting (PGP) attributes like phosphate solubilization and production of indole-3-acetic acid, siderophore, hydrogen cyanide, ammonia, and exopolysaccharide. This research describes two PGPR strains: Acinetobacter calcoaceticus AC06 and Bacillus amyloliquefaciens BA01. The present study demonstrated that these strains (AC06 and BA01) produced abundant osmolytes under osmotic stress, including proline (2.21 and 1.75 µg ml- 1), salicylic acid (18.59 and 14.21 µg ml- 1), trehalose (28.35 and 22.74 µg mg- 1 FW) and glycine betaine (11.35 and 7.74 mg g- 1) respectively. AC06 and BA01 strains were further evaluated for their multifunctional performance by inoculating in Arachis hypogaea L. (Groundnut) under mild and severe drought regimes (60 and 40% Field Capacity). Inoculation with microbial biostimulants displayed distinct osmotic-adjustment abilities of the groundnut, such as growth parameters, plant biomass, photosynthetic pigments, relative water content, proline, and soluble sugar in respective to control during drought. On the other hand, plant sensitivity indexes such as electrolyte leakage and malondialdehyde (MDA) contents were decreased as well as cooperatively conferred plant drought tolerance by induced alterations in stress indicators such as catalase (CAT), ascorbate peroxidase (APX), and superoxide dismutase (SOD). Thus, Acinetobacter sp. AC06 and Bacillus sp. BA01 can be considered as osmolyte producing microbial biostimulants to simultaneously induce osmotic tolerance and metabolic changes in groundnuts under drought stress.

Genomic Insights into Combating Anthracnose with an Endophytic Bacillus amyloliquefaciens Strain.

Anthracnose, caused by Colletotrichum spp., is a common disease of Camellia oleifera. In this study, a Bacillus amyloliquefaciens strain, GZY63, was isolated from fruit of the anthracnose-resistant cultivar of Ca. oleifera "Ganzhouyou7." Plate confrontation assays and field experiments demonstrated the strong inhibitory effect of GZY63 on anthracnose, and this strain exhibited broad-spectrum resistance to nine pathogenic Colletotrichum spp. This strain shows potential as a fungicide alternative, but genetic information on this strain is critical for its optimal use. Combining Illumina and Nanopore sequencing, we assembled a high-quality circular genome of GZY63 that contained no plasmids. The GZY63 complete genome was approximately 3.93 Mb and had an average guanine-cytosine content of 46.5%. The genome comprised 4,024 predicted coding sequences and 12 types of gene clusters involved in secondary metabolite production. This genome information provides insights into the mechanism underlying the antagonistic impact of the GZY63 strain on anthracnose and its symbiotic relationship with Ca. oleifera.

Inclusion of a Bacillus-based probiotic in non-starch polysaccharides-rich broiler diets.

This study examined the effects of a 3-strain Bacillus-based probiotic (BP; Bacillus amyloliquefaciens and two Bacillus subtilis) in broiler diets with different rye levels on performance, mucus, viscosity, and nutrient digestibility. We distributed 720 one-d-old female broilers into 72 pens and designed nine diets using a 3 × 3 factorial approach, varying BP levels (0, 1.2 × 106, and 1.2 × 107 CFU/g) and rye concentrations (0, 200, 400 g/kg). On d 35, diets with 200 or 400 g/kg rye reduced broiler weight gain (BWG). Diets with 400 g/kg rye had the highest FCR, while rye-free diets had the lowest (p ≤0.05). Adding BP increased feed intake and BWG in weeks two and three (p ≤0.05). It should be noted that the overall performance fell below the goals of the breed. Including rye in diets reduced the coefficient of apparent ileal digestibility (CAID) for protein, ether extract (EE), calcium, phosphorus, and all amino acids (p ≤0.05). Rye-free diets exhibited the highest CAID for all nutrients, except for methionine, EE, and calcium, while diets with 400 g/kg of rye demonstrated the lowest CAID (p ≤0.05). BP in diets decreased phosphorus CAID (p ≤0.05). Diets containing 1.2 × 107 CFU/g (10X) of BP exhibited higher CAID of methionine than the other two diets (p ≤0.05). Diets containing 10X of BP showed higher CAID of cysteine than diets with no BP (p ≤0.05). Ileal viscosity increased as the inclusion level of rye in the diets increased (p ≤0.05). The ileal concentration of glucosamine in chickens fed diets with 400 g/kg of rye was higher than in those fed diets with no rye (p ≤0.05). Furthermore, ileal galactosamine concentrations were elevated in diets with 200 and 400 g/kg of rye when compared to rye-free diets (p ≤0.05). However, BP in diets had no impact on ileal viscosity, galactosamine, or glucosamine (p > 0.05). In conclusion, the applied Bacillus strains appeared to have a limited capacity to produce arabinoxylan-degrading enzymes and were only partially effective in mitigating the negative impacts of rye arabinoxylans on broilers.

Effect of Bacillus amyloliquefaciens LSG2-8 on the intestinal barrier function of Amur minnow (Rhynchocypris lagowskii).

Probiotics are widely used in aquaculture. This article aims to study the effect of Bacillus amyloliquefaciens LSG2-8 on the intestinal barrier function of Rhynchocypris lagowskii. B. amyloliquefaciens LSG2-8 were added to R. lagowskii basal diets (CK) as additives at four concentrations: 1.0 × 106 (D-6), 1.0 × 107 (D-7), 1.0 × 108 (D-8) and 1.0 × 109 (D-9) CFU g-1 by dry weight of basal diet. After a 56-day feeding experiment, the activities of intestinal digestive enzymes and immunity-related enzymes of R. lagowskii on group D-6, D-7, D-8 and D-9 diet were significantly higher than the control (P < 0.05). In molecular experiments, the authors found that the levels of TGF-ß mRNA, IL-10 mRNA, ZO-1 mRNA and claudin-3 mRNA in group D-8 R. lagowskii were significantly higher (P < 0.05) than those of the control and other groups. Furthermore, the levels of IL-1ß and IL-8 mRNA of R. lagowskii on group D-6, D-7, D-8 and D-9 diet were significantly lower than those of the control (P < 0.05). In addition, the authors found that B. amyloliquefaciens LSG2-8 can regulate the intestinal flora balance and improve the intestinal structure of R. lagowskii. In conclusion, B. amyloliquefaciens LSG2-8 can improve the intestinal barrier function of R. lagowskii and can be used as a feed additive in aquaculture.

Bacterial Inoculant and Sucrose Amendments Improve the Growth of Rheum palmatum L. by Reprograming Its Metabolite Composition and Altering Its Soil Microbial Community.

Rheum palmatum L. is an important traditional Chinese medicinal herb now in demand worldwide. Recently, the theoretical framework suggested that sucrose triggers colonization of PGPM (plant growth-promoting microbes) in the rhizosphere, but their interactions on the plant remain largely unknown. Here, we applied three concentrations of both Bacillus amyloliquefaciens EZ99 inoculant (1.0 × 105, 1.0 × 106, and 1.0 × 107 colony-forming units (CFU)/mL, denoted as LB, MB, and HB, respectively) and sucrose (0.15, 1.5, and 15 g/L, denoted as LS, MS, and HS, respectively) to investigate their co-effects on R. palmatum in a field experiment. The results showed that LB + MS (1.0 × 105 CFU/mL Bacillus + 1.5 g/L sucrose) and LB + LS (1.0 × 105 CFU/mL Bacillus + 0.15 g/L sucrose) treatments significantly increased root fresh weight (p ≤ 0.05). Metabolite analysis revealed that the treatment LB + LS significantly increased the relative content of major active components in rhubarb, namely anthraquinones and phenolic compounds, by 1.5% and 2.3%. Although high sucrose addition increased the activities of certain soil enzymes, the LB + LS treatment significantly increased total potassium (TK), whereas it decreased available potassium (AK), which facilitated the potassium utilization in rhizosphere soil. Furthermore, rhizosphere microbiomes revealed that fungal diversity was augmented in LB + LS treatment, in which the common causative fungal pathogen Fusarium spp. showed an effective suppression. Additionally, the redundancy analysis and Spearman correlations revealed a positive relationship of Sphingomonas associated with change in potassium bioavailability. Altogether, our findings suggest that the combined application of a bacterial inoculant and sucrose can improve the growth and quality of R. palmatum, and stimulate uptake of plant nutrients that contribute to alter the microbial community for biocontrol potential. Hence, this work not only has broad application prospects across economical plants, but also emphasizes agroecological practices for sustainable agriculture.

Potassium Phosphite Enhances the Antagonistic Capability of Bacillus amyloliquefaciens to Manage Tomato Bacterial Wilt.

Bacterial wilt caused by Ralstonia solanacearum is a distributed and worldwide soilborne disease. The application of biocontrol microbes or agricultural chemicals has been widely used to manage tomato bacterial wilt. However, whether and how agricultural chemicals affect the antagonistic ability of biocontrol microbes is still unknown. Here, we combined potassium phosphite (K-Phite), an environmentally friendly agricultural chemical, and the biocontrol agent Bacillus amyloliquefaciens QPF8 (strain F8) to manage tomato bacterial wilt disease. First, K-Phite at a concentration of 0.05% (wt/vol) could significantly inhibit the growth of R. solanacearum. Second, 0.05% K-Phite enhanced the antagonistic capability of B. amyloliquefaciens F8. Third, the greenhouse soil experiments showed that the control efficiency for tomato bacterial wilt in the combined treatment was significantly higher than that of the application of B. amyloliquefaciens F8 or K-Phite alone. Overall, our results highlighted a novel strategy for the control of tomato bacterial wilt disease via application and revealed a new integrated pattern depending on the enhancement of the antagonistic capability of biocontrol microbes by K-Phite.

In Vitro and In Vivo Anti-Clostridioides difficile Effect of a Probiotic Bacillus amyloliquefaciens Strain.

Clostridioides difficile infection (CDI) is a significant cause of hospital-acquired and antibiotic-mediated intestinal diseases and is a growing global public health concern. Overuse of antibiotics and their effect on normal intestinal flora has increased the incidence and severity of infections. Thus, the development of new, effective, and safe treatment options is a high priority. Here, we report a new probiotic strain, Bacillus amyloliquefaciens (BA PMC-80), and its in vitro/in vivo anti-C. difficile effect as a prospective novel candidate for replacing conventional antibiotics. BA PMC-80 showed a significant anti-C. difficile effect in coculture assay, and its cell-free supernatant (CFS) also exhibited a considerable anti-C. difficile effect with an 89.06 µg/ml 50% minimal inhibitory concentration (MIC) in broth microdilution assay. The CFS was stable and equally functional under different pHs, heat, and proteinase treatments. It also exhibited a high sensitivity against current antibiotics and no toxicity in subchronic toxicity testing in hamsters. Finally, BA PMC-80 showed a moderate effect in a hamster CDI model with reduced infection severity and delayed death. However, further studies are required to optimize the treatment condition of the hamster CDI model for better efficacy and identify the antimicrobial compound produced by BA PMC-80.

Isolation and identification of an osmotolerant Bacillus amyloliquefaciens strain T4 for 2, 3-butanediol production with tobacco waste.

Microbial biomass and waste materials conversion for biochemicals production has been an alternative for energy conservation and emission reduction. While toxic substances in biomass materials and high osmotic pressure formed in fermentation-based systems block the bioconversion processes of microorganisms. In the present study, strain T4 that isolated from tobacco waste could resist toxic inhibitors such as nicotine and was suitable for generation of 2, 3-butanediol (2, 3-BD) with a high concentration of glucose (up to 20%). 30.06 and 1.54 g/L of 2, 3-BD was generated respectively from 50 g/L of tobacco waste with and without 200 g/L glucose after fermentation for 48 h. Besides, the results of biochemical tests showed that it was gram-positive and able to liquefy gelatin, hydrolyze starch and produce catalases. It could utilize glucose but not lactose as carbohydrates during fermentation. The 16S rRNA sequence and systematic analysis revealed that T4 was identified to be a Bacillus amyloliquefaciens (B. amyloliquefaciens). This work presents a promising model microorganism chassis to use the biomass waste for high value-added biochemicals production.

Novel amylomacins from seaweed-associated Bacillus amyloliquefaciens as prospective antimicrobial leads attenuating resistant bacteria.

The rise in antibiotic-resistant bacterial strains prompting nosocomial infections drives the search for new bioactive substances of promising antibacterial properties. The surfaces of seaweeds are rich in heterotrophic bacteria with prospective antimicrobial substances. This study aimed to isolate antibacterial leads from a seaweed-associated bacterium. Heterotrophic Bacillus amyloliquefaciens MTCC 12716 associated with the seaweed Hypnea valentiae, was isolated and screened for antimicrobial properties against drug-resistant pathogens. The bacterial crude extract was purified and three novel amicoumacin-class of isocoumarin analogues, 11'-butyl acetate amicoumacin C (amylomacin A), 4'-hydroxy-11'-methoxyethyl carboxylate amicoumacin C (amylomacin B) and 11'-butyl amicoumacin C (amylomacin C) were isolated to homogeneity. The studied amylomacins possessed potential activities against Pseudomonas aeruginosa, vancomycin-resistant Enterococcus faecalis, Klebsiella pneumoniae, methicillin-resistant Staphylococcus aureus, and Shigella flexneri with a range of minimum inhibitory concentration values from 0.78 to 3.12 µg/mL, although standard antibiotics ampicillin and chloramphenicol were active at 6.25-25 µg/mL. Noticeably, the amylomacin compound encompassing 4'-hydroxy-11'-methoxyethyl carboxylate amicoumacin C functionality (amylomacin B), displayed considerably greater antagonistic activities against methicillin-resistant S. aureus, vancomycin-resistant E. faecalis, Vibrio parahaemolyticus, Escherichia coli, and K. pneumoniae (minimum inhibitory concentration 0.78 µg/mL) compared to the positive controls and other amylomacin analogues. Antimicrobial properties of the amylomacins, coupled with the presence of polyketide synthase-I/non-ribosomal peptide synthetase hybrid gene attributed the bacterium as a promising source of antimicrobial compounds with pharmaceutical and biotechnological applications.

Bacillus amyloliquefaciens B10 inhibits aflatoxin B1-induced cecal inflammation in mice by regulating their intestinal flora.

Aflatoxin B1 is a mycotoxin that widely exists in feed and has a great impact on human and animal health. This study aimed to examine whether Bacillus amyloliquefaciens B10 protected against aflatoxin B1-induced cecal inflammation in mice. It was found that Bacillus amyloliquefaciens B10 could significantly improve the effects of AFB1 on body weight and intestinal inflammation of mice and enhance the expression of tight-junction protein. Compared with the CON group, the combination of AFB1 and B10 significantly increased the abundance of Actinobacteria and Bacilli in a collaborative manner, and significantly reduced the abundance of Ruminococcae, Lactobacillaceae and Clostridia. Meanwhile, the results showed that the abundance of Bacterides and Bacterdia in AFB1 + B10 group was significantly lower than that of AFB1 group, and the Firmicutes increased significantly. Bacillus amyloliquefaciens B10 can be used as a feed additive and alleviate cecal inflammation induced by AFB1 in mice by regulating intestinal flora.

The mutated Bacillus amyloliquefaciens strain shows high resistance to Aeromonas hydrophila and Aeromonas veronii in grass carp.

Bacillus amyloliquefaciens X030 (BaX030) has broad-spectrum antibacterial activity against the fish pathogens Aeromonas hydrophila and Aeromonas veronii. To improve its antibacterial effect, BaX030 was subjected to compound mutagenesis of atmospheric and room temperature plasma (ARTP) and nitrosoguanidine (NTG). The results showed that, compared with the original strain, the production of macrolactin A and oxydifficidin in mutated strain N-11 increased to 39 % and 268 %, respectively. The re-sequencing analysis suggested that there were SNPs and InDels in the gene clusters focused on the sucrose utilization pathway, glycolysis pathway and fatty acid synthesis pathway. Scanning electron microscopy revealed that strain N-11 became thin and long. The qRT-PCR results indicated that the expression of immune factors in the liver or kidney tissue of grass carp increased after feeding with N-11. H&E staining and protection experiments also showed that the mortality and surface symptoms of grass carp infected by the two pathogens were significantly reduced. The study identified a probiotic strain with potential application value in aquaculture production and provided a new strategy for the discovery of new strains with higher antibacterial biological activity.

Antifungal mechanism of Bacillus amyloliquefaciens strain GKT04 against Fusarium wilt revealed using genomic and transcriptomic analyses.

The application of endophytic bacteria, particularly members of the genus Bacillus, offers a promising strategy for the biocontrol of plant fungal diseases, owing to their sustainability and ecological safety. Although multiple secondary metabolites that demonstrate antifungal capacity have been identified in diverse endophytic bacteria, the regulatory mechanisms of their biosynthesis remain largely unknown. To elucidate this, we sequenced the entire genome of Bacillus amyloliquefaciens GKT04, a strain isolated from banana root, which showed high inhibitory activity against Fusarium oxysporum f. sp. cubense race 4 (FOC4). The GKT04 genome consists of a circular chromosome and a circular plasmid, which harbors 4,087 protein-coding genes and 113 RNA genes. Eight gene clusters that could potentially encode antifungal components were identified. We further applied RNA-Seq analysis to survey genome-wide changes in the gene expression of strain GKT04 during its inhibition of FOC4. In total, 575 upregulated and 242 downregulated genes enriched in several amino acid and carbohydrate metabolism pathways were identified. Specifically, gene clusters associated with difficidin, bacillibactin, and bacilysin were significantly upregulated, and their gene regulatory networks were constructed. Our work thereby provides insights into the genomic features and gene expression patterns of this B. amyloliquefaciens strain, which presents an excellent potential for the biocontrol of Fusarium wilt.

Bacillus amyloliquefaciens B10 can alleviate liver apoptosis and oxidative stress induced by aflatoxin B1.

Aflatoxin B1 (AFB1) is a mycotoxin often found in food and livestock feed. It can affect human and animal health and is especially damaging to the liver. This study aims to evaluate whether Bacillus amyloliquefaciens (hereafter referred to as B. amyloliquefaciens) B10 can alleviate the toxic effects of AFB1 and, if so, what mechanism is responsible for its action. Specific pathogen-free (SPF) Kunming mice (5-6 weeks old) were divided into four groups (Control, AFB1, B10 strain, and AFB1 + B10 strain) and conducted continuously via gavage for 28 days. Oxidation indices (MDA, T-AOC, SOD, GSH-Px, and CAT) were then measured using their liver tissues and liver coefficient were calculated. Apoptosis was determined using the TUNEL method. Gene expression was determined for Bax, Bcl-2, BIP, CHOP, JNK, Caspase-12, Caspase-9, and Caspase-3, and protein expression was detected for Bax, Bcl-2, and Caspase-3. Our results showed that AFB1 induced the oxidative damage and apoptosis in the livers of mice. However, for mice given B. amyloliquefaciens B10, the biochemical indices, pathological changes, the expressions of genes and proteins related to oxidative stress and apoptosis were significantly reversed. The results indicate that B. amyloliquefaciens B10 antagonizes oxidative damage and apoptosis induced by AFB1 in the livers of mice. The results of this study are of significance for the future use of this strain to reduce the harm of AFB1 to human health and animal reproductive performance.

Differential expression of bio-active metabolites produced by chitosan polymers-based Bacillus amyloliquefaciens fermentation.

Bacillus amyloliquefaciens strain PPL shows a potential for the control of phytopathogenic fungi. In the present study, upon growing the strain PPL on various forms of chitosan (0.5 % powder, 0.1 % soluble, and 0.15 % colloidal) as the carbon source, the antifungal activity on tomato Fusarium wilt correlated with the activity of chitosanase and ß-1,3-glucanase. The colloidal substrate-based strain PPL fermentation displayed the highest degree of spore germination inhibition (79.5 %) and biocontrol efficiency (76.0 %) in tomato by increased biofilm formation. The colloidal culture upregulated the expression of chitosanase gene (5.9-fold), and the powder attributed to the expression of cyclic lipopeptides-genes (2.5-5.7 fold). Moreover, the three chitosan cultures induced the morphological changes of Fusarium oxysporum. These results suggest that the choice of growth substrate synergistically affects the production of secondary metabolites by PPL strain, and consequently its antifungal activity.

Volatile compounds from beneficial rhizobacteria Bacillus spp. promote periodic lateral root development in Arabidopsis.

Lateral root formation is coordinated by both endogenous and external factors. As biotic factors, plant growth-promoting rhizobacteria can affect lateral root formation, while the regulation mechanism is unclear. In this study, by applying various marker lines, we found that volatile compounds (VCs) from Bacillus amyloliquefaciens SQR9 induced higher frequency of DR5 oscillation and prebranch site formation, accelerated the development and emergence of the lateral root primordia and thus promoted lateral root development in Arabidopsis. We demonstrated a critical role of auxin on B. amyloliquefaciens VCs-induced lateral root formation via respective mutants and pharmacological experiments. Our results showed that auxin biosynthesis, polar transport and signalling pathway are involved in B. amyloliquefaciens VCs-induced lateral roots formation. We further showed that acetoin, a major component of B. amyloliquefaciens VCs, is less active in promoting root development compared to VC blends from B. amyloliquefaciens, indicating the presence of yet uncharacterized/unknown VCs might contribute to B. amyloliquefaciens effect on lateral root formation. In summary, our study revealed an auxin-dependent mechanism of B. amyloliquefaciens VCs in regulating lateral root branching in a non-contact manner, and further efforts will explore useful VCs to promote plant root development.

Impact of Supplements on Enhanced Activity of Bacillus amyloliquefaciens BmB1 Against Pythium aphanidermatum Through Lipopeptide Modulation.

The present study has been designed to improve the activity of endophytic Bacillus amyloliquefaciens BmB1 against Pythium aphanidermatum through the culture supplementation with carbon sources, nitrogen sources and zinc oxide nanoparticles (ZnONPs). From the results of the study, supplementation with glucose (45 g/L), yeast extract (7.5 g/L) and ZnONPs (5 mg/L) were found to enhance the antifungal activity of B. amyloliquefaciens BmB1. This was also confirmed by comparative statistical analysis with experimental control. Further LC-Q-TOF-MS analysis of extracts of B. amyloliquefaciens BmB1 cultured with supplements showed a remarkable modulation of its lipopeptide profile. The blend of lipopeptides enhanced during the culture supplementation of B. amyloliquefaciens BmB1 as evidenced by the mass spectrometric analysis can consider to be the basis of its increased activity against P. aphanidermatum. As Bacillus spp. are well known for their biocontrol activities, the results of the study offer ways to improve its agricultural applications.

Seaweed-associated heterotrophic bacteria: new paradigm of prospective anti-infective and anticancer agents.

Ever since the development of the first antibiotic compound with anticancer potential, researchers focused on isolation and characterization of prospective microbial natural products with potential anti-infective and anticancer activities. The present work describes the production of bioactive metabolites by heterotrophic bacteria associated with intertidal seaweeds with potential anti-infective and anticancer activities. The bacteria were isolated in a culture-dependent method and were identified as Shewanella algae MTCC 12715 (KX272635) and Bacillus amyloliquefaciens MTCC 12716 (KX272634) based on combined phenotypic and genotypic methods. Further, the bacteria were screened for their ability to inhibit drug-resistant infectious pathogens and prevent cell proliferation of human liver carcinoma (HepG2) and breast cancer (MCF7) cell lines, without affecting the normal cells. Significant anti-infective activity was observed with bacterial cells and their organic extracts against broad-spectrum multidrug-resistant pathogens, such as vancomycin-resistant Enterococcus faecalis, methicillin-resistant Staphylococcus aureus, Klebsiella pneumonia and Pseudomonas aeruginosa with minimum inhibitory concentration ≤ 3.0 µg mL-1 as compared to the antibiotic agents' chloramphenicol and ampicillin, which were active at ≥ 6.25 mg mL-1. The extracts also exhibited anticancer activity in a dose-responsive pattern against HepG2 (with IC50, half maximal inhibitory concentration ~ 78-83 µg mL-1) and MCF7 (IC50 ~ 45-48 µg mL-1) on tetrazolium bromide screening assay with lesser cytotoxic effects on normal fibroblast (L929) cell lines (IC50 > 100 µg mL-1). The results revealed that seaweed-associated heterotrophic bacteria could occupy a predominant role for a paradigm shift towards the development of prospective anti-infective and anticancer agents.