This work aims to isolate and screen the fungicidal endophytic bacterial strains for biocontrol efficacy against Phytophthora palmivora, a soil-borne pathogenic fungus that kills durian trees worldwide. Among more than 100 isolates, 6 strains were screened as potential fungicidal strains with inhibitory efficiency of 67.4-79.8%. Based on 16S rRNA gene sequencing and phylogenetic analysis, these strains were identified as Bacillus amyloliquefaciens EB.CK9, Bacillus methylotrophicus EB.EH34, Bacillus amyloliquefaciens EB.EH18, Bacillus siamensis EB.KN10, Bacillus velezensis EB.KN15 and Paenibacillus polymyxa EB.KN35. In greenhouse tests, the two strains P. polymyxa EB.KN35 and B. velezensis EB.KN15 significantly reduced the damage to diseased roots by P. palmivora (33.3 and 35.6%, respectively), increased the rate of survival of durian trees (only 20.8 and 22.9% plant death, respectively), and showed a positive effect on promoting durian plant growth. Notably, the potential fungicidal effect of last two strains against P. palmivora was recorded for the first time in this work. HPLC analysis showed that these strains can secret several plant growth-promoting compounds, including gibberellic acid (GA3), indole-3-acetic acid (IAA), kinetin, and zeatin. Of these, GA3 and zeatin were produced with a significant amount by both strains. The volatiles bio-synthesized by these isolates were also identified using GC-MS analysis, and some major volatiles were found as fungicidal agents. This study suggested that P. polymyxa EB.KN35 and B. velezensis EB.KN15 may be potential biocontrol candidates for durian P. palmivora and bio-fertilizers for the sustainable production of durian crops.

BackgroundTomato yield is significantly reduced by root-knot nematodes (RKN; Meloidogyne spp.), particularly in tropical and subtropical regions. This study evaluated 20 bacterial isolates (B1-B20), belonging to the genera Bacillus, Lysobacter, Paenibacillus, and Streptomyces, from Sekem farms in Egypt for their potential to biocontrol RKN and stimulate plant growth in tomato 'Moneymaker.' The bacteria were compared to well-known microbial biocontrol agents (MBA), including Rhizobium etli G12 (B21), Pseudomonas trivialis 3Re2-7 (B22), Sporosarcina psychrophile Sd4-11 (B23), and B. subtilis Sb1-20 (B24), and a negative control, Escherichia coli JM109 (B25). The study involved seed-coated and -uncoated plants with bacterial isolates, planted in plastic pots, and inoculated with 1500 M. incognita J2 individuals per pot. Plants were grown in a saran-house during the 2022 and 2023 fall seasons, and their RKN-satisfying response (number of galls: NG and egg masses: NEM), vegetative growth, and metabolic activity were assessed 45 days after inoculation.ResultsIn seasons of 2022 and 2023, seed coating with bacterial isolates achieved a significant improvement in plant growth (coefficient of variation: CV ranging 26.8-120.2% in 2022 and 10.9-48.8% in 2023) and a reduction in RKN-satisfying response (CV for NG: 57.6 and 53.8%, respectively; and for NEM: 56.5 and 65.3%, respectively). Compared to uncoated-seed plants, the bacterial seed coating reduced NG by 0.66-74.09% in 2022 and 14.61-66.29% in 2023. Similarly, NEM decreased by 0.63-70.61% in 2022 and 41.91-77.46% in 2023. The coated-seed plants by Bacillus subtilis subsp. spizizenii (B5), Streptomyces subrutilus Wb2n-11 (B12), Streptomyces scabiei (B19), and Bacillus mojavensis (B20), along with the well-known MBAs B22 and B23, showed increased photosynthetic pigments, fresh weight of roots and shoots, stem size, and number of leaves. This growth has also led to higher dry weights in roots and shoots, and an increase in the root content of carbohydrates and proteins. Seed coating induced systemic RKN resistance by increasing polyphenols in the root. In contrast, uncoated-seed plants showed reduced foliar photosynthesis pigment and metabolic activity due to high RKN damage. Principal component analysis revealed significant correlations among the evaluated traits. Hierarchical clustering categorized bacteria isolates into five clusters based on their impact on estimated plant traits.ConclusionB5, B12, B19, B20, B22, and B23 demonstrated superior performance in both controlling RKN and stimulating vegetative growth in tomato 'Moneymaker' plants as known MBAs.

BACKGROUND Meloidogyne incognita is a highly damaging pathogenic nematode that causes significant annual economic losses. Therefore, the development of reliable biological control agents against M. incognita is imperative. The Bacillus velezensis RKN1111 strain, isolated from inter-root soil, demonstrates the ability to directly kill M. incognita. In this study, we investigated the effect of RKN1111 in inducing resistance to M. incognita in Cucumis sativus and examined changes in the content of immune-responsive substances in the induction-treated cucumber plants. RESULT The RKN1111 treatment reduced the number of root galls in infected cucumbers, with a maximum reduction of 78.19%. RKN1111 stably colonized cucumber roots, reaching 3.65 x 106 CFU/g in 3 days. The approach and infestation rates of M. incognita on RKN1111-induced treated cucumber root tips declined at varying time points. Furthermore, RKN1111 induced significant increases (P < 0.05) in hydrogen peroxide (H2O2) and superoxide anion (O2-) contents, as well as in the callose deposition area in cucumber, by up to 59.84, 83.28, and 61.59%, respectively. CONCLUSION RKN1111 has been demonstrated to stably colonize cucumber root systems and defend against M. incognita infestation by inducing systemic resistance in the host plant. Additionally, RKN1111 elevated the levels of immune-responsive substances in cucumber plants. RKN1111 has great potential for application in the integrated pest management of M. incognita. (c) 2025 Society of Chemical Industry.

Heavy metal pollution is a global issue that poses significant risks to ecosystems and human health. Microorganisms offer a promising bioremediation approach due to their ability to mitigate metal-induced metabolic damage in an eco-friendly, efficient, and cost-effective manner. Among them, Gram-positive Bacillus species exhibit a high heavy metal adsorption capacity and secrete metabolites with diverse functional properties. Under heavy metal stress, these metabolites play a crucial role in alleviating metal-induced damage. However, the application of Bacillus metabolites in heavy metal remediation faces challenges, including prolonged treatment durations, the necessity for stable environmental conditions, and specific nutrient requirements.This review summarizes recent research on the effects of heavy metal exposure on the metabolic pathways and metabolites of Bacillus spp., elucidates their role in influencing metal bioavailability and chemical transformations, and explores innovative strategies to enhance the stability of Bacillus-mediated heavy metal remediation. The review aims to provide valuable insights for optimizing bioremediation strategies, facilitating the selection of efficient degrading strains, and advancing the sustainable management of heavy metal contamination.

Pesticide contamination has become a major environmental concern with organophosphates such as chlorpyrifos emerging as major pollutants posing significant risks to both ecosystems and human health. Chlorpyrifos is widely used in agriculture to control pests, however due to its persistence, its accumulation in soils can lead to long-term environmental damage. The objective of this study was to isolate and characterize chlorpyrifos-degrading bacteria from a tobacco field exposed to intensive pesticide use in T & uuml;rkiye. To achieve this, a selective enrichment strategy was employed to promote the growth of chlorpyrifos-degrading microorganisms. Two distinct experimental setups were established to target both normally growing and slower-growing bacteria: the first involved a 4-week incubation with weekly subculturing as described in the literature, while the second applied an 8-week incubation with biweekly subculturing. At the end of the enrichment period, bacterial loads were compared between the two groups. Four of the nine bacterial isolates were obtained from the newly tested long-term setup. Among all isolates, members of the genus Pseudomonas exhibited the best adaptation to the prolonged enrichment conditions. Additionally, isolates belonging to the genera Klebsiella, Sphingobacterium, and Peribacillus were isolated from the normally growing group. Two isolates (AB4 & AB15), identified as Sphingobacterium thalpophilum, were determined to be novel chlorpyrifos degraders. This is the first reported study from T & uuml;rkiye focusing on the biodegradation of chlorpyrifos by native soil bacteria. The findings revealed that various ecological areas, constitute potential sources for new microbial metabolic processes and these bacterial strains can be used in bioremediation studies.

The development of microbial chassis strains with high rare earth element (REE) tolerance is critical for the advancement of new metal biomining and bioprocessing technologies. In this study, we present a mechanistic understanding of how hyperacidophilic bioleaching organism Acidithiobacillus ferrooxidans resists REE-mediated damage at concentrations of REEs as high as 100 mM, while mesophilic Escherichia coli BL21 is significantly inhibited by far lower concentrations of REEs (IC50 between similar to 5 mu M and similar to 140 mu M depending on the element). Using light microscopy to document physiological changes and fluorescent probes to quantify membrane quality, we prove that cell surface interactions explain REE toxicity and demonstrate its reversibility through the addition of chelators. Removal of the A. ferrooxidans outer membrane and cell wall confers REE sensitivity comparable to that of E. coli, corroborating the importance of the outer membrane surface. To conclude, we present a model of differential REE sensitivity in the two strains tested, with implications for industrial metal bioprocessing. IMPORTANCE Demand for rare earth elements (REEs), a technologically critical group of metals, is rapidly increasing (US Geological Survey, 2024. Mineral commodity summaries. Reston, VA). To expand the supply chain without creating environmentally hazardous conditions, there is growing interest in the application of bioprocessing and bioextraction techniques to REE mining and separation. While REE toxicity has been demonstrated in Escherichia coli and other mesophilic neutrophiles, the effect of REEs on organisms currently used in metal bioleaching has been less studied. We present physiological evidence suggesting that REEs damage the outer membrane of E. coli, resulting in growth inhibition that is reversible by chelation. In contrast, Acidithiobacillus ferrooxidans tolerates saturating REE concentrations without apparent inhibition. This study fills gaps in the rapidly expanding body of literature surrounding REE's impact on microbial physiology. Furthermore, A. ferrooxidans resistance to REEs at saturating concentrations (50-100 mM at pH 1.6) is unprecedented in the literature and demonstrates the potential utility of this organism in REE biotechnology.

Probiotics are living microorganisms when administered in adequate amounts confer health benefits to the host. In the present study, a soil isolate was identified as Bacillus subtilis based on the 16S rRNA sequencing. In probiotic functional characterization (in vitro), B. subtilis SKB/2074 produced 10 different enzymes, was stable under simulated gastric conditions (pH 2.5/1-3 hr), bile salt (0.05-0.3% w/v), and temperature (40-90 degrees C) conditions. B. subtilis SKB/2074 cells were non-hemolytic, found susceptible to the 30 antibiotics, and showed antimicrobial activity against Escherichia coli, Salmonella typhimurium, and Clostridium perfringens. In in vivo studies, B. subtilis SKB/2074 demonstrated encouraging results to reverse E. coli and castor oil incited diarrhea in Wistar rats and Albino mice, respectively. Histopathological studies exhibited restoration of damaged mucosal epithelium cells and recovers veracity of goblet cells (colon). B. subtilis SKB/2074 exhibited immunomodulatory effects (increased immunoglobulins in blood and weight of spleen and thymus) and significant antioxidant activity (84.14%), reducing capacity and ascorbate auto-oxidation inhibition effect (95.13%). In poultry field studies, B. subtilis SKB/2074 significantly improved growth performance and lowered mortality rate in broiler chickens. Based on these preliminary scientific assessments B. subtilis SKB/2074 is likely to be used as potential probiotic and antidiarrheal agent in humans and animal healthcare.

BackgroundIn winter, tea plants are highly susceptible to low-temperature freezing damage. The rapid recovery of tea plant vigor in spring is crucial for tea yield and quality. Some studies have reported that Bacillus mucilaginosus could improve the stress resistance of plants. However, there were no reports on the effect of B. mucilaginosus on the recovery of tea plant vigor after low-temperature stress. This study firstly used different concentrations of B. mucilaginosus to spray tea leaves and used 16S rRNA high-throughput sequencing technology to study the impact of different treatments on tea leaf endophytic populations. Meanwhile, physiological indexes such as Soil and plant analyzer development values (SPAD), maximum photochemical quantum yield of PS II (Fv/Fm), and superoxide dismutase (SOD) were measured and analyzed in tea plant leaves of different treatments, and the correlation between them and the bacterial community was studied.ResultsMicrobial results showed that the diversity of leaf endophytic populations treated with different concentrations of Bacillus mucilaginosus (T1, T2, T3) was higher than that in control group (CK) leaves, and T2 treatment had the highest diversity. The dominant bacterial phyla of all samples were Proteobacteria, Actinobacteriota, Firmicutes, and Bacteroidota. At the phylum level, the relative abundance of Actinobacteriota, Firmicutes, and Bacteroidota in leaves treated with B. mucilaginosus was significantly higher than that in the control. At the genus level, the relative abundance of Paenibacillus, Nocardioides, and Marmoricola in leaves treated with B. mucilaginosus was significantly higher than that in the control. Different concentrations of B. mucilaginosus affected the distribution of leaf endophytic populations. At the level of bacterial function, abundant metabolic functional features were observed, including amino acid transport and metabolism, as well as energy production and conversion, indicating that bacterial metabolism in tea plant leaf samples tends to be vigorous. The treatment with B. mucilaginosus significantly increased the activity of antioxidant enzymes and osmolyte content, promoted the recovery of Fv/Fm in tea plants after low-temperature stress, and improved the resistance of tea leaves to low-temperature stress, thereby promoting recovery.ConclusionsThis study showed that B. mucilaginosus could significantly change the community structure of leaf endophytic populations, and increase antioxidant enzyme activity and osmolyte content in tea plants after low-temperature stress, promoting the rapid recovery of photosynthesis, and thereby benefiting the recovery of tea plant leaves. This study provided a theoretical basis for the application of B. mucilaginosus in practical production and also provided new ideas for the recovery of tea plants exposed to low-temperature stress.

BackgroundLow soil temperature and its fluctuation can negatively impact the growth of seedlings. The district of Cooch Behar (India), belonging to the Cwa zone (according to Koppen's classification), receives several cold waves during winter. Our previous study demonstrated that a constant temperature of 20 degrees C (chilling but not freezing) can cause a loss in the vigor of tomatoes. Since the temperature of the soil is not uniform throughout the day, we hypothesized that the duration of cold exposure can have variable effects on seed vigor.ResultsIt was observed that increasing the duration of cold stress can slow down the germination process and reduce vigor. This was due to the cold-mediated damage to cell membranes (due to dehydration) which caused electrolyte leakage and reduced levels of glutathione reductase. In this regard, biopriming seeds with microbes that produce exopolysaccharide (EPS) can be useful as it can form a protective layer on the seeds. Indigenous EPS-producing bacteria, Bacillus, Phytobacter and Priestia sp., were used for biopriming. Priestia and Phytobacter sp. not only reduced the electrolyte leakage but also increased the levels of antioxidant genes. This improved the germination speed and vigor. In a field trial, the rhizosphere of the seedlings pretreated with bioinoculants displayed a reduced thermal fluctuation compared with the untreated seeds.ConclusionThe seedlings treated with bioinoculants grew faster in soil in spite of low soil temperature. This can reduce the nursery time of seedlings. (c) 2025 Society of Chemical Industry.

BackgroundEnergy flows in most food chains in the agroecosystem are crowned with beneficial natural enemies including different species of predatory and parasitic insects, birds and animals. They are utilized in organic and IPM cotton production to replace the conventional insecticides usually applied in cotton production.ResultsNatural populations of six coccinellids, five staphylinids and two carabids (Coleoptera), three anthocorids and three reduviids (Heteroptera), five syrphids (Diptera, three labidurids (Dermaptera), two chrysopids (Neuroptera) and one thripid (Thysanoptera) species were manipulated in Egyptian clover to aggregate in seed production stripes (stripe technique) adjacent to and across the cotton fields during April-May, 2022. These 30 predatory species represent 112 energy flow routes in food chains preying on tetranychid mites, aphids, thrips, whiteflies and cotton leaf worm attacking cotton plants during vegetative growth stage beginning from April to May 2022. High populations of these predators develop along the clover season (November-May) on different pests where no insecticide applications occur. They aggregate in the flowering clover stripes left for seed production feeding on nectar, pollens and remaining pests. By dryness of the clover stripes, populations of all these predatory species abandon the clover, migrating outwards into the adjacent cotton or corn fields showing an excellent high protection against cotton pests suppressing their populations far away under the level of economic threshold damage during vegetative growth stage. Dressing cotton seeds with Bacillus amyloliquefaciens as antagonist protects the seedlings from soil-borne diseases. Insect pheromone traps detected the first appearance of the pink bollworm, Pectinophora gossypiella (Saund.) moths, the cotton bolls are attacked also by the spiny bollworm, Earias insulana (Boisd.). The egg parasitoid Trichogramma evanescens (West.) was released in 6 successive releases to guide the energy flow in favor of the parasitoid by getting it from egg contents of these two pests, which resulted in high protection of cotton bolls. This study aims better understanding of biodiversity and the routes of energy flow among the complex net of food chains governing the bio-dynamics in the Egyptian agroecosystem, which enabled the development of the present strategy to completely abandon application of the conventional insecticides and chemical fertilization for organic cotton production in Egypt.ConclusionThe study is an approach contributing to improvement of the agroecosystem and production of healthy crops.