Proteolytic Potential Actinobacteria from Cemetery Soil in Surakarta, Central Java, Indonesia

Abstract

Human corpses contain approximately 20% protein, enriching cemetery soil with proteinaceous matter that supports proteolytic microorganisms, especially Actinobacteria known for producing bioactive compounds. Several studies related to burial soil and corpse decomposition have been conducted outside Indonesia for forensic purposes, archaeology, and pathogen transmission risk. However, there is still limited exploration of proteolytic Actinobacteria from cemetery soils in Indonesia. This study aimed to screen potential proteolytic isolates of Actinobacteria from cemetery soil and to identify them based on the 16S rRNA gene. As many as 29 isolates from the collection of Actinobacteria were screened for their proteolytic potential using Skim Milk Agar media. Potential proteolytic Actinobacteria were characterized for their morphology, including spore type, and were molecularly identified. The results showed that 25 isolates have proteolytic potential, with the highest Proteolytic Index of 6.5 (isolate T41), which is very close to Streptomyces albidoflavus strain ZLC-20 with 99.79% similarity. Its aerial mycelium and vegetative mycelium are white, and the colony surface is powdery with a radial circle around the main colony and closed spiral spores. It was concluded that cemetery soil, especially from Bonoloyo, Surakarta, Indonesia, stores potential proteolytic Actinobacteria. Moreover, the results of this study discovered the potential of cemeteries as sources of proteolytic microorganisms, which may enrich the collection of protease-producing microorganisms that are applicable in various fields of industrial biotechnology.