Faculty Publications

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Production and characterization of biosurfactant produced by a novel Pseudomonas sp. 2B
(2012) Aparna, A.; Srinikethan, G.; Smitha, H.
Biosurfactant-producing bacteria were isolated from terrestrial samples collected in areas contaminated with petroleum compounds. Isolates were screened for biosurfactant production using Cetyl Tri Ammonium Bromide (CTAB)-Methylene blue agar selection medium and the qualitative drop-collapse test. An efficient bacterial strain was selected based on rapid drop collapse activity and highest biosurfactant production. The biochemical characteristics and partial sequenced 16S rRNA gene of isolate, 2B, identified the bacterium as Pseudomonas sp. Five different low cost carbon substrates were evaluated for their effect on biosurfactant production. The maximum biosurfactant synthesis (4.97g/L) occurred at 96h when the cells were grown on modified PPGAS medium containing 1% (v/v) molasses at 30°C and 150rpm. The cell free broth containing the biosurfactant could reduce the surface tension to 30.14mN/m. The surface active compound showed emulsifying activity against a variety of hydrocarbons and achieved a maximum emulsion index of 84% for sunflower oil. Compositional analysis of the biosurfactant reveals that the extracted biosurfactant was a glycolipid type, which was composed of high percentages of lipid (~65%, w/w) and carbohydrate (~32%, w/w). Fourier transform infrared (FT-IR) spectrum of extracted biosurfactant indicates the presence of carboxyl, hydroxyl and methoxyl functional groups. The mass spectra (MS) shows that dirhamnolipid (l-rhamnopyranosyl-l-rhamnopyranosyl-3-hydroxydecanoyl-3-hydroxydecanoate, Rha-Rha-C 10-C 10) was detected in abundance with the predominant congener monorhamnolipid (l-rhamnopyranosyl-?-hydroxydecanoyl-?-hydroxydecanoate, Rha-C 10-C 10). The crude oil recovery studies using the biosurfactant produced by Pseudomonas sp. 2B suggested its potential application in microbial enhanced oil recovery and bioremediation. © 2012 Elsevier B.V..
Isolation of Novel Aerobic denitrifier and optimization of process parameters for biological denitrification using RSM
(Slovak University of Agriculture info@jmbfs.org, 2019) Joshi, K.; Navalgund, N.; Shet, V.B.; Srinikethan, G.; Ashwini; Sneha; Anusha; Aparna, A.
The study aimed to isolate and characterize a high efficiency novel bacterium for denitrification in waste water and also to optimize process parameters under aerobic condition. One of the bacteria chosen among four, displayed a maximum of 98% reduction of nitrate. The strain was identified as Enterobacter sp. NCCP-29 by biochemical tests and further identified based on similarity of PCR-16S rRNA using universal primers. The parameters (pH, temperature, agitation speed, C:N ratio) which effect the denitrification were screened using one factor at a time. The pH, temperature and C:N ratio exhibited significant effect on the denitrification using Enterobacter sp. NCCP-29. The levels of these parameters were optimized using a central composite design (CCD). A maximum of 98% denitrification was achieved at pH 6.5, temperature 30°C and C: N ratio of 3:1. The second order model was generated and found to have a good fit with R2 value of 0.93. Investigations revealed the ability of Enterobacter sp. NCCP-29 to remove nitrate under aerobic conditions. © 2019, Slovak University of Agriculture.
Methyl orange dye adsorbed biochar as a potential Brønsted acid catalyst for microwave-assisted biodiesel production
(Springer, 2023) Chellappan, S.; Aparna, A.; Sajith, S.; Nair, V.; Chinglenthoiba, C.
Biodiesel production from non-edible oils utilizing a highly efficient eco-friendly catalyst is a crucial necessity for replacing fossil fuels. In the present work, biochar has been applied for both energy and environmental purposes. The biochar was made by slow pyrolysis from a variety of biomass, primarily cassava peel, irul wood sawdust, and coconut shell. All biochars were used as adsorbents to remove an anionic dye (methyl orange) by conducting batch adsorption studies. The biochar made from cassava peels showed the highest dye adsorption, and it was characterized using elements analysis (CHNS), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscopy (SEM), surface area analyzer (BET), total acid density, and sulfonic acid group density to successfully confirm the presence of weak (–OH) and strong (–COOH, –SO3H) acidic groups. Furthermore, for microwave-assisted biodiesel production from Millettia pinnata seed oil, the dye adsorbed biochar made from cassava peel was utilized as a Brønsted acid catalyst. The catalyst having a surface area of 4.89 m2/g, an average pore width of 108.77 nm, a total acid density of 3.2 mmol/g, and a sulfonic acid group density of 1.9 mmol/g exhibits distinctive mesoporous properties that contribute to a biodiesel yield of 91.25%. By utilizing the catalyst for three more cycles and getting a yield of more than 75%, the reusability of the catalyst was investigated. © 2023, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.

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