Production of keratinase under solid-state fermentation (SSF) by Bacillus sp. MD24 and potential of its liquid by-product as organic fertilizers.

Keratinase is a specific proteolytic enzyme that degrades keratin. Keratinase has wide applications in global industries. Bacillus sp. MD24 has been reported to produce keratinase by solid-state fermentation method using chicken feathers as a sole substrate. Furthermore, keratinase production could be elevated by adding biomass waste (sugarcane bagasse, tofu waste, or rice husk) to chicken feathers. However, the ratio of biomass waste addition was unknown. The liquid by-product of keratinase production contains both carbon and nitrogen sources, which is potential as organic fertilizer. This study aimed to determine the effect of chicken feathers and an additional carbon source ratio toward keratinase production by Bacillus sp. MD24 and potential of its liquid by-products as organic fertilizer. This research was conducted in several stages: keratinase production, enzyme assay, testing liquid by-product on the growth of caisim, and plant morphological analysis. The results showed that the addition of tofu waste produced higher keratinase compared to other carbon sources. The optimal ratio between chicken feathers and tofu waste to produce optimal keratinase was 1:0,4 on the 6^th day. Growth rates, the number of leaves, and chlorophyll a and b pigments increased significantly with 20-days irrigation at 1:5 and 1:10 (v/v) dilution. [ABSTRACT FROM AUTHOR]