Lina Maziyyatus Salamah, Nur Faridah, Andriyani Andriyani, Suharti Suharti
Keratin in chicken feathers has potential as a raw material for wood adhesives because it has functional groups from amino acid side chains that are able to cross-link with lignin in wood. The solid structure of keratin in chicken feathers needs to be converted into a soluble structure through a degradation step in order to be applied as a wood adhesive. Chemical degradation of keratin in chicken feathers cannot control the results of hydrolysis which causes keratin to be degraded into amino acids and produces hazardous chemical waste. Enzymatic degradation is an environmentally friendly alternative. Previous research reported that Bacillus sp. MD24 and 2 microbial isolates from Pasuruan salt pond water, namely TG3 and TG6 isolates were able to produce keratinase. Keratinase from each microbe is thought to have the ability to degrade by cutting at different specific keratin sites. Thus, the microbial consortium may be able to increase the concentration of soluble keratin hydrolyzate with more diverse molecular weights. This research was conducted with an experimental laboratory design. The steps carried out in this study include: (1) Confirming the ability of TG3 and TG6 isolates to produce keratinase; (2) Identification of TG3 and TG6 isolate species using 16s rRNA genomic methods; (3) Optimization of the humidity of the fermentation medium for TG3 and TG6 isolates; (4) Trial of microbial consortium isolates TG3 and TG6 with Bacillus sp. MD24?in keratinase fermentation. The environmental conditions of keratinase fermentation were carried out at 37°C and pH 8 using the Solid-State Fermentation method. TG3 and TG6 isolates have been tested for their ability to produce keratinase seen from their ability to degrade keratin in chicken feathers as much as 11.20% and 14.50% for 2 days of incubation, respectively. Species identification of isolates TG3 and TG6 showed that they were closely related to Salinivibrio proteolyticus with a similarity percentage of 99.13% and 99.14%, respectively. The optimization of the humidity of the fermentation medium showed that on the third day of incubation, both showed the highest optimum activity at variations in the ratio of chicken feather weight (g): volume of salt solution pH 8 (mL) 1:3. In this study, the microbial consortium of Bacillus sp MD24 with isolates TG3 and TG6 was not able to significantly increase the degradation ability of chicken feathers and the protein content of keratin hydrolyzate. This is possibly because the characteristics of the optimum pH and temperature of the enzymes produced by each microbe are different, so that in the microbial consortium it is necessary to select 2 isolates of microbes that have almost the same optimum characteristics of enzymes. © 2023 Author(s).
Departement of Chemistry, Faculty of Mathematics and Natural Science, Universitas Negeri Malang, Jl. Semarang 5, Malang, 65145, Indonesia