AN ASSESSMENT ON POTENTIAL OF β-GALACTOSIDASE PRODUCTION FROM PROBIOTICS ISOLATED FROM DAIRY PRODUCTS OF HIMACHAL PRADESH AND ITS IMMOBILIZATION
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Date
2018-11
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UHF, NAUNI
Abstract
ABSTRACT
The present investigation was carried out to isolate most efficient potential lactic acid bacteria
from dairy products of Himachal Pradesh were screened β-galactosidase production, identification,
safety assessment, evaluation of probiotic attributes, optimization, characterization and
immobilization of the purified β-galactosidase. Dairy products being a highly probable source for βgalactosidase
producing microorganisms was utilized as a source for isolation of β-galactosidase
producing lactic acid bacteria. Total 56 bacteria were isolated, after tentatively identification 40 were
lactic acid bacteria. Out of 40, 14 β-galactosidase producing LAB have been screened from different
dairy products. Among them, hyper β-galactosidase producing strains MK4 and MB2 were selected
and identified as Lactobacillus sp. MK4 and Lactobacillus casei MB2 |MH823224|. Safety
assessment of β-galactosidase producing isolates was done by evaluating haemolytic, DNase and
gelatinase activities. All the isolates exhibited non-heamolytic, non-DNase and non-gelatinase
activities, thereby proving their safe status. These screened isolates were further examined for their
probiotic potential viz. Bacteriocinogenicity, siderophore production, antioxidant activity and
cholesterol assimilation. Both the screened isolates show good probiotic properties. Further, the
cultural conditions and process parameters viz. incubation period, pH, temperature, inoculum size,
incubation time, substrate concentration, divalent ions and surfactants etc. were optimized firstly
through classical one variable at a time (OVAT) followed by statistical optimization by placketburman
design. The enzymes obtained from both the strains were purified to homogeneity by
following a sequential purification approach. Lactobacillus sp. MK4 was purified to a final
purification fold of 1.66 and had a molecular weight of 25.5 kDa whereas Lactobacillus casei MB2 βgalactosidase
was purified to a final purification fold of 2.52 and had a molecular weight of 30.5 kDa.
β-galactosidase activity was found to be maximum at 30 °C and pH 7.0 for both the isolates. βgalactosidase
from both the strains was thermostable with retention of more than 50% activity after
incubation of 120 min at 25-45 °C. Immobilization of purified β-galactosidase from Lactobacillus
sp. MK4 onto natural polymer chitosan show
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