Aug 2026· Journal of Basic Microbiology· Vol 66· 0 citations· 44 references
Medicine
TL;DR
Overall, NBAIR Bt25 emerged as a promising multifunctional strain with strong insecticidal activity, plant growth‐promoting ability, and biocontrol potential, making it a suitable candidate for sustainable pest management and climate‐smart agriculture.
Abstract
Bacillus thuringiensis is the most widely used microbial bioinsecticide; however, only a few strains possess additional traits such as plant growth promotion and biocontrol potential. This study characterized 25 B. thuringiensis isolates obtained from soil and infected insect cadavers to identify multifunctional strains with insecticidal and plant growth‐promoting (PGP) properties. Microscopic examination revealed diverse parasporal crystal morphologies, while 16S rRNA sequencing confirmed their identity with 99%–100% similarity to reference strains. Enzymatic profiling showed protease activity in 24 strains and lipase activity in 21 strains, whereas all isolates produced lecithinase and chitinase. All strains produced indole‐3‐acetic acid (11.22–31.87 µg mL−1) and ammonia (26.74–77.68 µg mL−1), while phosphate solubilization and siderophore production were observed in 21 and 11 strains, respectively. Bioassays against Spodoptera frugiperda identified five highly virulent strains causing more than 90% larval mortality. Among these, NBAIR Bt25 showed the highest efficacy, causing 92% mortality within 96 h with an LC50 of 39.75 µg mL−1. PCR analysis revealed that NBAIR Bt25 carries multiple pesticidal genes (cry1A, cry1D, cry1E, cry1I, cry2A, and vip3A). Paper towel and glasshouse assays demonstrated that strain NBAIR Bt25 significantly enhanced shoot growth and secondary root development. Overall, NBAIR Bt25 emerged as a promising multifunctional strain with strong insecticidal activity, plant growth‐promoting ability, and biocontrol potential, making it a suitable candidate for sustainable pest management and climate‐smart agriculture.
This is the first report describing Bacillus stercoris as a multifunctional endophytic biocontrol and plant growth-promoting bacterium associated with taro, highlighting their potential as eco-friendly bioinoculants for the sustainable management of taro leaf blight.
Sreekumar Usha Shilpa, M. Jeeva, S. S. Veena et al.· 3 Biotech· 0 citations
Bacterial wilt caused by Ralstonia solanacearum remains difficult to manage sustainably, creating a need for compatible native microbial antagonists with complementary biocontrol traits. This study isolated four rhizosphere microorganisms—Trichoderma viride (Tv), Pseudomonas fluorescens (Pf), Bacillus subtilis (Bs) and Azotobacter chroococcum (Ac)—from healthy eggplant plants surviving in bacterial-wilt-affected fields and assessed their antagonistic, biochemical, plant-growth-associated and compatibility characteristics. In dual-culture assays, Pf showed the highest inhibition of R. solanacearum (68.50%; 18.40 mm inhibition zone), followed by Bs (55.40%; 15.60 mm). Hydrolytic enzyme screening indicated overlapping amylase, protease and lipase activities among the antagonists, with Bs showing a 16.5 mm protease clearance zone and Pf a 14.2 mm zone. Siderophore screening showed the largest CAS halo for Pf (22.40 mm), which also exhibited a strong positive reaction for HCN production. Ac produced the highest indole-3-acetic acid concentration (32.60 µg/ml), followed by Pf (28.40 µg/ml). Cross-streak assays showed no visible inter-strain inhibition among Tv, Pf, Bs and Ac under the tested conditions. These findings indicate complementary in vitro functional traits and preliminary mutual compatibility among the four isolates, supporting their further evaluation as candidate components of a multi-strain biocontrol consortium. Molecular identification, formulation assessment and greenhouse and field validation remain necessary before practical application.
B. J. Praveen Biradar, R. Lakshmipathi· Journal of Advances in Micro...· 0 citations
Pronounced cultivar × treatment interactions confirmed that PGPR efficacy is modulated by host genetic background, with resistant varieties carrying pyramided Xa resistance genes showing additive responses to biological treatment.
S. Naqvi, Ateeq ur Rehman, Ummad ud Din Umar· World Journal of Microbiolog...· 0 citations
Quinoa leaf spot is an important fungal disease that limits quinoa yield and quality. This study aimed to evaluate the pathogenicity of isolates associated with quinoa leaf spot in Qinghai, China, and to screen multifunctional biocontrol bacteria with potential for further development. Pathogenicity assays conducted on healthy quinoa leaves showed that isolates Alternaria alternata AF15 and A. tenuissima AF18 induced typical leaf spot symptoms. The corresponding fungi were successfully re-isolated from the resulting lesions, confirming the pathogenicity of both isolates. Two highly effective biocontrol bacteria, Serratia liquefaciens CB82 and Bacillus velezensis CB316, were subsequently selected through dual-culture assays. Their maximum inhibition rates against the two fungal pathogens reached 56.00% and 57.00%, respectively. Both biocontrol strains exhibited broad adaptability to different temperatures, pH, and NaCl conditions, produced protease, amylase, and cellulase, and showed phosphate-solubilizing activity. Metabolite extraction and fractionation revealed that the antifungal substances were predominantly enriched in the n-butanol fractions, which caused severe shrinkage, surface roughening, breakage, and deformation of the pathogen hyphae. In addition, both strains exhibited strong biofilm-forming capacity and successfully colonized quinoa leaves. Their culturable populations peaked on day 3 after inoculation, reaching 5.58 × 107 and 6.06 × 107 CFU/mL, respectively. In seed germination pouch assays, the bacterial suspensions promoted quinoa root elongation, whereas the fermentation broths increased seedling biomass accumulation in pot experiments. Overall, this study confirmed the pathogenicity of fungal isolates associated with quinoa leaf spot in Qinghai, China, identified two promising biocontrol bacterial strains, and preliminarily characterized their antifungal substances. These findings provide valuable microbial resources and a research basis for the future development of biological control strategies against quinoa leaf spot.
