Identifying Extremophilic Actinomycetes Effective Against Multidrug-Resistant Bacterial Pathogens and Demonstrating High Enzyme Activities

Abstract

Objective: This study focused on isolating actinomycetes from an unexplored arid region of Saudi Arabia. Methods: Actinobacteria were isolated on starch nitrate agar and identified using molecular techniques. All isolated screened for antibacterial and enzyme activities. Results: Twenty-two different isolates were obtained on starch nitrate agar. Identification via 16S rRNA sequencing showed that 86.4% belonged to the genus Streptomyces, with one isolate related to Lentzea albidocapillata. The actinomycetes were tested for enzyme production (amylase, protease, keratinase, gelatinase, chitinase, and lipase) and antibacterial activity against various pathogens, including Staphylococcus aureus, methicillin-resistant Staphylococcus aureus (MRSA), Enterococcus faecalis, Acinetobacter baumannii, Klebsiella oxytoca, and Escherichia coli. Eight isolates exhibited antibacterial activity, with AL3 being effective against all tested Gram-positive bacteria and showing the largest inhibition zones. The crude extract from AL3 demonstrated strong activity against E. faecalis. In conclusion, actinomycetes from extreme habitats can produce valuable antibiotics and enzymes, highlighting the potential for further bioprospecting in similar and unique ecological regions of Saudi Arabia.