Low temperature active pectinases production by Saccharomyces cerevisiae isolate and their characterization

The objective of the present study was to isolate a yeast strain from fruit wastes and able to produce pectinases by submerged fermentation. Among 5 positive pectinolytic yeast isolates screened, one exhibited strong pectinolytic activity with highest zone (1.6 cm) of pectin hydrolysis in ruthenium red plate assay. This yeast was identified as Saccharomyces cerevisiae by morphological characteristics and 26 S rRNA gene analysis. The yeast isolate has been characterised as low temperature active pectinase producer in flasks containing YEPD medium and commercial citrus pectin as substrate. Time course studies of submerged fermentation revealed that the enzymes production is growth associated and maximum enzyme activities were obtained after 48 h of incubation. The strain was able to produce both polygalacturonase (PG) and pectin lyase (PL). The physicochemical properties of pectinases were determined by the study of the effect of temperature and pH on its production and found to be optimum for PG and PL at pH 4.5 and 6.0, respectively, optimum temperature was 30 °C for both the enzymes. The partially purified and characterised enzymes showed the presence of isoforms. Further the enzyme tested for depolymerisation capacity of fruit peel pectin and juice clarification potential. These novel pectinases were low temperature active and moderately thermostable have prospects of application in fruit peel pectin degradation which was studied by using scanning electron microscopy (SEM). Finally we have studied the effect of temperature on clarification of fruit juices, which infers the potential of this yeast-pectinases for commercial and industrial exploitation.