Activities of Cellulolytic, Amylolytic, and Secondary Metabolites from Thermophilic Actinomycetes Collected from the Heated Soil around Cisolok Geyser

This study investigated the antimicrobial activity, cellulolytic, and amylolytic abilities of eight thermophilic Actinomy-cetes isolated from the heated soil around the Cisolok geyser, West Java, Indonesia. Cellulolytic and amylolytic abili-ties were screened for on media by adding 1% (w/v) soluble starch and carboxymethylcellulose (CMC), respectively. Antimicrobial activity was screened for using the agar-plug diffusion method by cultivating strains on various growth media. Growth at various temperatures showed that six strains could grow up to 50 °C. Seven out of eight strains showed amylolytic ability at 40 °C and 45 °C, and only four strains did so at 50 °C. Screening for cellulolytic ability showed that seven strains could hydrolyze CMC at 40 °C, whereas seven and five strains could hydrolyze at 45 °C and 50 °C, respectively. Antibacterial activity showed that strains UICC B-110 and UICC B-118 grown on various media could inhibit the growth of Gram-positive bacteria. The results of the antifungal activity test showed that strain UICC B-118, incubated for seven and 14 days, could inhibit the growth of Candida albicans. Based on 16S rRNA gene se-quence similarity and phylogenetic analyses, strains UICC B-110 and UICC B-118 were identified as Streptomyces glaucescens and Microbispora rosea subsp. rosea, respectively. These results show that thermophilic Actinomycetes from the soil around the Cisolok geyser have the potential as a source of thermostable enzymes and new bioactive compounds with antimicrobial activity.