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Kerala Veterinary and Animal Sciences University, Wayanad

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20211
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Subject: Dairy Microbiology × Author: MARIYA DIVANSHI A S × Thesis Type: M.Tech. ×
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    ThesisItemOpen Access
    BIOREMEDIATION POTENTIAL OF LACTIC ACID BACTERIA AGAINST CADMIUM AND LEAD
    (COLLEGE OF DAIRY SCIENCE AND TECHNOLOGY MANNUTHY, THRISSUR, 2021-12-31) MARIYA DIVANSHI A S; Aparna Sudhakaran V
    Cadmium and lead tolerant lactic acid bacteria were isolated from dairy effluent, soil sample, chikoo fruit (Manilkara zapota), breast milk and neonatal fecal matter and optimised their bioremediation potential against cadmium and lead. 16srRNA sequencing confirmed the isolates as Lactobacillus plantarum, Lactobacillus fermentum, Fructobacillus tropaeoli, Pediococcus pentosaceus and Weissella confusa respectively. The nucleotide sequences so obtained were deposited in NCBI with accession numbers MT158675, MT158674, MT158673, MT158672 and MT158671. Minimum inhibitory concentrations (MIC) of the five isolates were evaluated and the highest MIC of 600 mg/L and 2500 mg/L had shown by Weissella confusa for both cadmium and lead respectively. Multiple antibiotic resistance index was also maximum for Weissella confusa. Evaluation of biosorption potential revealed that out of all the isolates, highest biosorption efficiency for cadmium was recorded by Weissella confusa (14.20%) and for lead by Lactobacillus plantarum (51.40%). Both of them were exopolysaccharide producers. Scanning electron microscopy also confirmed the adsorption of metal ions to the cell surface. Therefore, Weissella confusa and Lactobacillus plantarum were selected for optimization of different factors. Five factors namely pH, metal concentration, inoculum rate, temperature and contact time affected the lead biosorption significantly. However, in the case of cadmium biosorption, only inoculum rate, metal concentration and contact time had a significant effect. As suggested by the two factor interaction response surface model, the optimized condition for cadmium biosorption by Weissella confusa was one per cent inoculum rate, 50 mg/L concentration of cadmium and 30 h of contact time. The quadratic model fitted for lead biosorption recommended the optimum condition as pH 7, 30⁰C temperature of incubation, one per cent inoculam rate, 50 mg/L concentration of lead and 30 h of contact time were the optimum conditions for effective biosorption by Lactobacillus plantarum.