Search

This study explores the comparative effect of conventional and organic treatments on the rhizosphere microbiome of Mangifera indica cv. Dashehari. The long-term exposures (about 20 years) were monitored under a subtropical ecosystem. Based on plant growth properties and acetylene reduction assay, 12 bacterial isolates (7 from G1-organic and 5 from G2-conventional systems) were identified as Pseudomonas and Bacillus spp. In the conventional system, dehydrogenase activity significantly decreased (0.053 µg TPF formed g−1 of soil h−1) and adversely affected the bacterial diversity composition. In comparison, organic treatments had a good impact on dehydrogenase activity (0.784 µg TPF formed g−1 of soil h−1), alkaline phosphatase (139.25 µg PNP g−1 soil h−1), and bacterial community composition. The Metagenomics approach targeted the V3 and V4 regions to see the impact in the phylum, order, family, genus, and species for both the treatments. Results showed that phylum Acidobacteria (13.6%), Firmicutes (4.84%), and Chloroflexi (2.56%) were dominating in the G2 system whereas phylum Bacteroides (14.55%), Actinobacteria (7.45%), and Proteobacteria (10.82%) were abundantly dominated in the G1 system. Metagenome sequences are at the NCBI-GenBank sequence read archive with SRX8289747 (G1) and SRX8289748 (G2) in the study PRJNA631113. Results indicated that conventional and organic conditions affect rhizosphere microbiome and their environment.

Ubiquitous presence of cypermethrin as a contaminant in surface stream and soil necessitates to develop potential bioremediation methods to degrade and eliminate this pollutant from the environment. A cypermethrin utilizing bacterial strain (MIC, 450 ppm) was isolated from the soil of pesticide contaminated agriculture field and characterized by using polyphasic approach. On molecular basis bacterial isolate showed 98% homology with Bacillus subtilis strain 1D. Under optimized growth conditions, bacteria showed 95% degradation of cypermethrin after 15 days and the end products of cypermethrin biodegradation under aerobic conditions were cyclododecylamine, phenol, 3-(2,2-dichloroethenyl 2,2-dimethyl cyclopropane carboxylate,1-decanol,chloroacetic acid, acetic acid, cyclopentan palmitoleic acid, and decanoic acid. Amplification of esterase (700 bp) and laccase (1200 bp) genes was confirmed by PCR which showed a possible role of these enzymes in biodegradation of cypermethrin. In the presence of cypermethrin Km value(s) of both the enzymes was low than the control. A nobel cypermethrin degradation pathway followed by B. subtilis was proposed on the basis of characterization of biodegraded products of cypermethrin using GC-MS. Cypermethrin biodegradation ability of Bacillus subtilis strain 1D without producing any toxic end product reveals the potential of this organism in cleaning of pesticide contaminated soil and water.