Biosurfactants are secondary metabolites with surface active properties and have wide application in agriculture, industrial and therapeutic products. The present study was aimed to screen bacteria for the production of biosurfactant, its characterization and development of a cost effective media formulation for iturin A production. A total of 100 bacterial isolates were isolated from different rhizosphere soil samples by enrichment culture method and screened for biosurfactant activity. Twenty isolates were selected for further studies based on their biosurfactant activity [emulsification index (EI%), emulsification assay (EA), surface tension (ST) reduction] and antagonistic activity. Among them one potential isolate Bacillus sp. RHNK22 showed good EI% and EA with different hydrocarbons tested in this study. Using biochemical methods and 16S rRNA gene sequence, it was identified as Bacillus amyloliquefaciens. Presence of iturin A in RHNK22 was identified by gene specific primers and confirmed as iturin A by FTIR and HPLC. B. amyloliquefaciens RHNK22 exhibited good surface active properties and antifungal activity against Sclerotium rolfsii and Macrophomina phaseolina. For cost-effective production of iturin A, 16 different agro-industrial wastes were screened as substrates, and Sunflower oil cake (SOC) was favouring high iturin A production. Further, using response surface methodology (RSM) model, there was a 3-fold increase in iturin A production (using SOC 4%, inoculum size 1%, at pH 6.0 and 37 °C temperature in 48 h). This is the first report on using SOC as a substrate for iturin A production.

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Bacillus amyloliquefaciens strain RHNK22 isolated from groundnut rhizosphere showed direct and indirect plant growth-promoting traits along with biosurfactant activity and reduction in surface tension of water. Biosurfactants were identified as lipopeptides (surfactin, iturin, and fengycin) by molecular and biochemical analysis in our studies.

Hexavalent Cr is most toxic metal and hazardous compound worldwide. It is also considered to be cellular oxidizing pollutant causing damage, mutagenic and hematopoietic effects to living systems. Present work is focused on synthesis of zero valent iron nano particles (Fe-NPs) using Bacillus subtilis SHB 13, Achromobacter xylosoxidans SHB 204 and Surfactin and their application for Cr (VI) detoxification (100 ppm) in synthetic solutions and polluted sludge, sewage and soil samples about 90-100% reduction observed with above particles. Qualitative analysis, structural characterization of Fe-NPs, adsorption, and recovery of Cr (VI) were carried out using XRD, SEM and TEM. This work explains adsorption isotherm of Cr with iron nano particles (Fe- NPs), was best fitted with Langmuir model and it followed first order rate kinetic reaction. Microcosm studies were carried out using Fe-NPs in sludge, sewage and tannery samples and Cr (VI) was completely (100 %) removed within 72 h. In another microcosm experiment, bacteria were able to reduce (60-70 %) Cr (VI) from soils with and without moisture and glucose. In green house experiments both the bacteria were able to reduce Cr (VI) (65-90%) effectively from both polluted and non-polluted soil and there was increase in root length and shoot length of plant L. esculentum was observed and maximum plant biomass was observed with plants inoculated with SHB 204 and SHB 13.