Alkaline Protease Production by Immobilized Klebsiella aerogenes Cells from Dairy Effluent Sludge

Abstract

This study investigated the screening of alkaline protease microorganism from diary effluent sludge and identified by 16S ribosomal RNA nucleotide  sequence as Klebsiella aerogenes with accession number MF156964.1 and maximum identity 95.45%. The cells were immobilized with coconut pod husks  and optimization studies such as the effects of particle sizes, pH, temperature, agitation speed, and incubation time were determined. Out of  twenty three microorganisms screened, three were potential protease producers. K. aerogenes gave the highest zone of hydrolysis (35 mm) on the  skimmed milk agar plate. The particle size (0.075 mm2) of the immobilization agent gave the highest enzyme activity 176.83 U/mL. The optimum  incubation time for the production of protease was 48 h with enzyme activity 143.054 U/mL which further declined. The optimum pH of the protease was  pH 9.0 with activity 209.61 U/mL which made it alkaline. The agitation speed 150 rpm resulted in a protease activity 175.83 U/mL and reduced by 56.5% at  250 rpm. The optimal temperature 35 ºC was 183.78 U/mL. This study also confirmed the stability and reusability of the immobilized cells using the  coconut pod husks matrix by maintaining from 100% to 76.2% up to six times recycle. Conclusively, the study established the efficiency of low cost, readily  available matrix and reusability potentials of coconut pod husks for cells immobilization technology through entrapment at optimal conditions for  protease production.