Distribution, isolation and characterization of bacteria with industrial potential in Lake Nakuru, Kenya

Abstract

Lake Nakuru is an economically important natural resource in Kenya. Despite the unique ecological characteristics exemplified by this lake, the industrial potential of microbes in the lake has barely been explored. The main objective of this study was to determine the distribution of bacteria, isolate and characterize bacteria with industrial potential. This was achieved through intensive ecological study of three sites on the lake for a period of six months (January to June 2010). Total bacterial counts were determined by direct epifluorescence microscopy of acridine orange stained samples on black polycarbonate filters. Heterotrophic plate counts were plated on 4% NaCl and 1 % Na2CO3 nutrient agar. Enzymatic activities of bacteria towards various macromolecules were investigated for 30 selected isolates by testing their ability to degrade such substrates as starch, cellulose, casein and lipids. The potential use of bacterial isolates for feather degradation was determined by allowing isolates to grow on a feather waste medium as the sole source of carbon and nitrogen. Genomic DNA of four isolates (LNS08, LNC09, LNC11 and LNC06) that showed highest potential to degrade macromolecules and feathers was amplified by PCR and subsequently sequenced. Temperature and pH variations in the lake were low throughout the sampling duration. Dissolved oxygen varied tremendously in the lake with a high value of about 18.4±5.1 mg/l in February and a low mean value of 2.08mg/l in April 2010 when a highest rainfall event occurred and consequently higher total counts (TC) and heterotrophic plate counts (HPC) were recorded. There were significant (P<0.05) temporal and spatial variations in terms of HPC and TC and this was factored by the rainfall event with the Northern side of the lake being significantly different from the South and Central points. Of the 30 bacterial isolates from Lake Nakuru, 24 showed ability to degrade macromolecules with 26.7% degrading starch, 20% proteins, 16.7% cellulose and 16.6% lipids while for 20% of isolates no enzymatic activity was recorded. DNA analysis revealed identity of four isolates with industrial potential to be closely related to known bacteria viz; Nesterenkonia lacusekhoensis (LNS08), Bacillus agaradhaerens (LNC06) and Bacillus sp. Acc No: AB043860.1(LNC09 and LNC11). Bacillus agaradhaerens showed best potential for industrial application in the degradation of chicken feathers. Bacillus sp. Acc No: AB043860.1has potential industrial production of sugars from starch and cellulose. Nesterenkonia lacusekhoensis is a lipid degrader. The results of this work indicated that Lake Nakuru is a rich source of many alkaliphilic bacteria which could be a good source of interesting enzymes from the industrial point of view.