ABSTRACT
BACKGROUND: Mosquitoes are widespread globally and have contributed to transmitting pathogens to humans and the burden of vector-borne diseases. They are effectively controlled at their larval stages by biocontrol agents. Unravelling natural sources for microbial agents can lead us to novel potential candidates for managing mosquito-borne diseases. In the present study, an attempt was made to isolate a novel bacterium from the field-collected agricultural soil for larvicidal activity and promising bacterial metabolites for human healthcare. METHODS AND RESULTS: Field-collected soil samples from the Union territory of Puducherry, India, have been used as the source of bacteria. Isolate VCRC B655 belonging to the genus Lysinibacillus was identified by 16S rRNA gene sequencing and exhibited promising larvicidal activity against different mosquito species, including Culex (Cx.) quinquefasciatus, Anopheles (An.) stephensi, and Aedes (Ae.) aegypti. The lethal concentration (LC) of Lysinibacillus sp. VCRCB655 was observed to be high for Cx. quiquefasciatus: LC50 at 0.047 mg/l, LC90 at 0.086 mg/l, followed by An. stephensi and Ae. aegypti (LC50: 0.6952 mg/l and 0.795 mg/l) respectively. Additionally, metabolic profiling of the culture supernatant was carried out through Gas chromatography and Mass spectrophotometry (GC/MS) and identified 15 major secondary metabolites of different metabolic classes. Diketopiperazine (DKPs), notably pyro lo [1, 2-a] pyrazine1, 4-dione, are the abundant compounds reported for antioxidant activity, and an insecticide compound benzeneacetic acid was also identified. CONCLUSIONS: A new bacterial isolate, Lysinibacillus sp. VCRC B655 has been identified with significant larvicidal activity against mosquito larvae with no observed in non-target organisms. GC-MS analysis revealed diverse bioactive compounds with substantial biological applications. In conclusion, Lysinibacillus sp. VCRC B655 showed promise as an alternative biocontrol agent for mosquito vector control, with additional biological applications further enhancing its significance.
Subject(s)
Bacillaceae , Gas Chromatography-Mass Spectrometry , Larva , Mosquito Control , RNA, Ribosomal, 16S , Animals , Bacillaceae/isolation & purification , Bacillaceae/metabolism , Bacillaceae/genetics , Gas Chromatography-Mass Spectrometry/methods , Mosquito Control/methods , Larva/microbiology , RNA, Ribosomal, 16S/genetics , India , Soil Microbiology , Anopheles/microbiology , Culex/microbiology , Phylogeny , Aedes/microbiology , Insecticides/pharmacologyABSTRACT
A strain of Bacillus amyloliquefaciens (VCRC B483) exhibiting mosquito pupicidal, keratinase and antimicrobial activities was isolated from mangrove forest ecosystem of Andaman and Nicobar Islands. Molecular characterization of the strain showed the presence of lipopeptide encoding bmyC gene. Phylogenetic tree based on protein sequence of this gene exhibited homology with mycosubtilin synthetase of Bacilus atropheus and Iturin synthetase of Bacillus subtilis and B. amyloliquefaciens. This is the first report on the evolutionary conservation of amino acids concerned with the function and structure of bmyC protein of B. amyloliquefaciens. The presence of valine at the 1197th position in our strain was found to be unique and different from the existing strains of B. subtilis and B. amyloliquefaciens. Molecular modelling studies revealed significant changes in the structure of epimerization domain of the bmyC protein with A1197V variation. Crude metabolite of this strain exhibited antifungal activity against Fusarium sp. and Carvularia sp.
