Isolation and molecular identification of Exiguobacterium profundum from drain water and study of some physiological properties

Abstract

Some microorganisms' stress tolerance and adaptability through the ability to live in new environments previously considered hostile to dense microbial growth. The aim of the study: In this work, the isolation, molecular identification, and analysis of some physiological properties of Exiguobacterium profundum isolated from washing machine drain water were carried out. Fifteen samples were collected from different washing machines' drain water, and 42 isolates were characterized and identified. Based on the morphological assay and 16S rRNA gene sequencing, one isolate was designated as Exiguobacterium profundum Kh-Am2 and was deposited in the Gene bank database under the accession number MW447498.1. The physiological properties assay showed that E. profundum could not decompose red blood cells while proving their ability to decompose crude and coconut oil, producing lipopeptide biosurfactants. It has also demonstrated its ability to form biofilm using the tube method, which helps it to live in harsh environments such as the environment of washing machines. The results showed that E. profundum is halotolerant bacteria with its ability to grow at a concentration of ( 75) g/l NaCl and the best growth was at( 25) g/l NaCl concentration. The results also showed the effect of different concentrations of NaCl on E. profundum, where the best movement rate was at a concentration of ( 25 )g/l NaCl, while the movement was completely inhibited at a concentration of (75)g/l NaCl. We have concluded that E. profundum possesses traits that enable it to live in harsh environments. Keywords. Exiguobacterium profundum, drain water, biosurfactant