Phenotypic characterization of pectinase-producing alkaliphilic microbial isolates from Lake Bogoria, Baringo County, Kenya

Alkaline pectinases are in demand in industrial processes that require the degradation of plant pectins at high pH, e.g., removal of pectin stains from fabrics, cutlery, and porcelain; treatment of pectic wastewater; fermentation of coffee, tea, and cocoa; manufacture of poultry and animal feeds, and processing of textiles, etc. The present study aimed to a) screen four alkaliphilic microbial isolates, previously obtained from samples collected around Lake Bogoria (soda lake), Baringo County, Kenya, for alkaline pectinases, and b) characterize the pectinase-producers. The screening data revealed that all the isolates were pectinase producers, exhibiting catalytic activities that ranged from 1.4 - 1.6 pectinolytic indices (PI) (primary screening) and 0.04 - 0.15 U/ml (secondary screening). These isolates’ colonies featured smooth textures and umbonate elevations and were moist, white, or cream. Their cells were motile, aerobic rods that were Gram-, catalase-, and oxidase-positive. They utilized inositol, sucrose, lactose, and glucose and hydrolyzed starch, pullulan, casein, and gelatin. They grew optimally at pH 10.5, 45 °C, and without NaCl but tolerated growth at higher temperatures (up to 55 °C) and saline conditions [up to 12.5 % (w/v) NaCl]. At neutral pH, no growth was detected. Based on these phenotypic characteristics, the Lake Bogoria alkaliphilic microbial isolates were identified as Bacillus halodurans , capable of producing alkaline pectinases that, if harnessed, can potentially find applications in the aforementioned industrial processes.