Isolation and Characterization of Thermostable Enzyme-Producing Microbes from Selected Hot springs of Ethiopia

Abstract

Hot springs are springs that occur naturally at elevated temperatures, originated when water seeps into the earth and come contact to the magma near to earth’s surface and are potential sources of microbial diversity and thermostable hydrolytic enzymes. Cross sectional and experimental study design was conducted to isolate and characterize thermostable enzyme-producing microbes from selected hot springs of Ethiopia. A total of 90 samples 30 from each hot springs, Woliso, Wondo Genet, and Shalla were collected from three different locations and different depths. Isolation of thermophiles was done by enriching samples in peptone water for 24 hours and conducting serial dilution followed by spread plating the samples on nutrient agar supplemented with 1% agar and thermus agar for bacteria and potato dextrose agar supplemented with 1% agar was used for fungi. Then, the isolated bacterial and fungal isolates were screened for the production of thermostable hydrolytic enzyme (amylase, protease, cellulase, and lipase) using their respective enzyme screening media and then the formation of a clear zone and opaque zone around the colony was detected as enzyme production. A total of 252 bacterial isolates and 9 fungal isolates were obtained after sub-culturing. All of the 252 bacterial isolates were producers of 1 or more enzymes they were screened for but all the fungal isolates were not capable of producing a promising clear zone for all the tested enzymes. Based on the highest clear zone formation 45 bacterial isolates were selected for biochemical and physiological characterization. Based on their biochemical characterization, 39 of the bacterial isolates were tentatively classified under the genus Bacillus and the rest 6 isolates were identified to the genus Thermus. Among these, isolates JUWG84 (30.5 ± 0.71) and JUW103 (30 ± 0), JUS4 (29.5 ± 0.71) and JUS14 (29.5 ± 0.71), JUWG44 (30 ± 0) and JUWG9 (30 ± 0) obtained the higher inhibition zone and were recognized as excellent amylase, protease, cellulase and lipase producers respectively. Seven of the isolated fungal isolates were identified as genus Aspergillus and two were identified as genus Penicillium. It is concluded that the three hotsprings studied in this study are rich with microbial community and the microbes are an important source of thermostable enzymes for industrial application. So industries need to use microbial-based enzymes by applying extra screening, optimization, and scale-up.