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Subject: Agricultural Business Management × Author: Basavaraj M. Kurabet × End date: 2017 × Start date: 2012 × Thesis Type: M.Sc ×
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    ThesisItemOpen Access
    Isolation and Functional Characterization of Lactic Acid Bacteria From Different Sources
    (UAS, Dharwad, 2012) Basavaraj M. Kurabet; K.S. Jagadeesh
    An attempt was made to isolate lactic acid bacteria (LAB) from different sources and characterize them in terms of agriculturally important functional characteristics. Totally, 97 isolates of LAB were isolated from different sources such as dairy products, rhizhosphere soils, fruits, vegetables, sprouted grains and fermented foods. The isolates were characterized based on morphological and biochemical characteristics. Cells varied in their shape like, rod and cocci. All the isolates were Gram-positive, and negative for catalase. Based on acid and gas production tests, the isolates were grouped into homo and heterofermentative LAB. Further, the isolates were screened for beneficial characters. The results revealed that the highest indole acetic acid production was recorded in the isolate LAB 63 (grapes) (73.65 μg/ml), which was higher than the reference strain. The isolates were also tested for Psolubilization activity. None of the isolates showed any P-solubilization activity. The antagonistic activity of the LAB isolates against fungal pathogens like Aspergillus flavus and Colletotrichum capscici was studied. None of the isolates inhibited the growth of the fungal pathogens. The antibacterial activity of the LAB isolates against bacterial pathogens like Xanthomonas axonopodis pv. punicae and Ralstonia solanacerum was studied. The highest zone of inhibition of 17.25 dia. (in mm) of X. axonopodis pv. punicae was recorded by the isolate LAB 92 (karadant) which was higher than the reference strain. All the isolates were subjected for exopolysaccharide (EPS) production. Although all the isolates produced EPS, LAB 67 (rhizhosphere soil greengram) produced the highest amount (93.2 μg/ml) of exopolysaccharide. All the isolates were examined for lactic acid production. The maximum lactic acid production was observed in the isolate LAB 72 (rhizhosphere soil soybean) (8.2%), which was significantly higher than that of the reference strain. All the isolates were tested for methionine production qualitatively through thin layer chromatography (TLC). Out of 97 isolates, only 12 isolates showed positive for methionine production, as indicated by their Rf values. With regard to lactic acid production, the isolate LAB 72 (rhizhosphere soil soybean) was more promising and has potential to be utilized industrially after thorough investigations including optimization studies.