Isolation and Identification of Yeast Strains with High Beta-galactosidase Activity from Dairy Products
Titel:
Isolation and Identification of Yeast Strains with High Beta-galactosidase Activity from Dairy Products
Auteur:
I. Nahvi H. Moeini
Verschenen in:
Biotechnology
Paginering:
Jaargang 3 (2004) nr. 1 pagina's 35-40
Jaar:
2004
Inhoud:
In this study of twenty-five samples which were collected from dairy producing centers in the city of Isfahan, 30 yeast strains were isolated using Malt Extract Broth (MEB) containing 0.1 gl?1 chloramphenicol and Yeast Extract Glucose Chloramphenicol Agar (YGCA). Of the isolated strains, 11 with the ability to lactose fermentation were isolated (M1-M11). These strains were identified by morphological and physiological properties. From these 11 strains, six were identified as Kluyveromyces lactis, four as Kluyveromyces marxianus and one as Candida versatilis. In the next step, the amount of produced single cell protein, SCP, from whey; whey including nitrogen supplementation and whey with mixed yeast cultures in these strains was measured. Among these strains, M2 that was identified as K. lactis had the most SCP production from whey with 11.79 gl?1. It was found that the ammonium sulfate as a nitrogen source has a significant effect on biomass yield so that amount of produced biomass of the M11 strain (K. marxianus) increase from 11.54 gl?1 (from whey without nitrogen supplementation) to 15.75 gl?1 (in the presence of nitrogen source). The co-cultures of yeast strains with Saccharomyces cerevisiae were evaluated. In the mixed yeast cultures of these yeast strains and S. cerevisiae, the M2 strain which was identified as K. lactis had the most biomass production, 22.38 gl?1. ONPG assay of beta-galactosidase in yeast strains found that a strain of K. lactis (M2) has the highest enzyme activity (8103 Eu ml?1). These strains can be used for removal of whey pollutant, SCP & ethanol production and treatment of lactose in dairy food.
Uitgever:
Asian Network for Scientific Information, Pakistan (provided by DOAJ)
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