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Subject: Microbiology × Author: Dolly Rani × End date: 2019 × Start date: 2019 ×
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    ThesisItemOpen Access
    Biochemical characterization and toxicity Studies of biosurfactants produced by yeast
    (CCSHAU, 2019) Dolly Rani; Sangwan, Seema
    The biosurfactant production potential of two yeasts, Meyerozyma guilliermondii YK 32 and M. guilliermondii YK 22 was investigated using total eight types of carbon sources followed by extraction and characterization of final product. Maximum biosurfactant production monitored in terms of oil displacement (9.0cm) was obtained using a mixture of olive oil and whey at 4%(v/v) concentration of each in case of M. guilliermondii YK 32. Its cell free supernatant yielded maximum 12.77g/L crude biosurfactant using acetone precipitation method. Total eight types of crude biosurfactants obtained using different carbon sources (BS1-BS8) were subjected to further characterization. The preliminary characterization using TLC revealed yellow spots in case of BS1, BS4, BS5 and BS8 having Rf 0.33, 0.41, 0.45 and 0.38, respectively indicating the presence of carbohydrate and lipids while a ninhydrin spray detected purple to reddish purple spots in BS2, BS3, BS6 and BS7 with Rf value varied from 0.23 to 0.93 depicting protein and lipid contents. The biosurfactant produced using a mixture of olive oil and whey (BS6) as substrate contained highest protein content (28.61 mg/g) followed by BS2 (20.90 mg/g) and BS1 (15.94 mg/g) while a mixture of molasses and whey supported the production of crude biosurfactant (BS8) containing highest carbohydrate (28.82 mg/g) as well as lipid content (A260nm, 16.85). All the crude biosurfactants exhibited neutral behavior during ionic charge determination. Contrary to chemical surfactant (1%SDS) which inhibited the germination of chickpea, the increasing concentration of biosurfactants supported the germination of chickpea giving a maximum germination index equaled to 423 % at 0.8% concentration of biosurfactants BS4.Further, all the biosurfactants were non toxic to yeast multiplication and did not show any antimicrobial activity against Rhizobium, a bioinoculant for nitrogen fixation. Being supportive to chickpea germination and nontoxic to yeast, the neutral biosurfactant produced by M. guilliermondii YK 32 may be tested for application in agricultural practices, cosmetics and pharmaceutical industries.