Keratinase characterization of protease producing halophilic bacteria using BK-1H isolate from Bledug Kuwu Mud Crater, Central Java

• Main Authors: Permatasari, Indah, Faridah, Nur, Suharti, Suharti
• Format: Conference Proceeding
• Language: English
• Subjects: Bacteria; Calcium ions; Cobalt; Enzyme activity; Enzymes; Feathers; Gene sequencing; Hazardous wastes; Ions; Leather; Metal ions; Mud; Protease; Tanning industry
• ISSN: 0094-243X; 1551-7616
• DOI: 10.1063/5.0131216

Keratinase is an alternative material used in the dehairing process of leather tanning industry to minimise production of hazardous waste. In the preservation process, leather soaked in high salt content solution, thus high salt tolerant keratinase is needed in this industry. By using halophilic bacteria isolated from the Bledug Kuwu mud crater, the BK-1H isolate is expected to have keratinase activity that can be used in the dehairing process of leather tanning. Isolate BK-1H used in this research refer to previous research that shown the high proteolitic index. The isolate needed to be identified for their ability to produce enzymes. The research stage include : (1) Gram staining and observation of bacterial colony morphology, (2) characterization of proteases by determining the optimum pH and temperature of the enzyme, and knowing the effect of metal addition on enzyme activity, (3) the variation effect of pH, time, and humidity to enzymes activity, (4) the ability of bacteria to degrade chicken feathers, (5) the ability of enzymes to degrade chicken feathers, and (6) genotypic identification of isolates using 16S rRNA gene sequencing. BK-1H was identified as a rod-shaped Gram-negative bacteria. Protease produced by BK-1H showed a maximum activity of 4,083 U/mL at 46 °C. The highest activity value for pH optimum is 1.308 (±0.243) U/mL, at pH 7. The addition of metal ions Zn2+, Ca2+, Co2+, and Mg2+ decrease enzymes their activity so that further testing is needed for other metal ions. The effect of variations pH at the time of enzyme production showed the highest yield at pH 10 with the optimum time of enzyme production within 2 days. The results of the sequencing showed the relations between BK-1H to Bacillus swezeyi with an identity percentage of 98.51%.