Peptide Analysis from Soil Actinomycetes Exhibiting Antimicrobial and Antiproliferative Activities

Abstract

Actinomycetes are considered a potential group of microorganisms capable of producing bioactive
molecules. In the present study, the actinomycetes species belonging to the genus Thermoactinomycetes,
Micromonospora and predominantly Streptomyces were isolated from maize rhizosphere soil and from
compost soil. With anticipating the isolation of potential antimicrobial peptides from the actinomycetes
isolates, the isolates were subjected for total protein extraction after growing them in starch casein nitrate
media. The antimicrobial peptides are low molecular weight peptides attacking the cell membrane by
ionic interactions, thus disrupting membrane integrity of invading pathogens or the abnormal cells such
as cancer cells. The peptides obtained from actinomycetes were analyzed by SDS-PAGE technique after
their salt precipitation and dialysis. The total peptides were checked for antimicrobial activity against the
bacteria Pseudomonas sp, Enterobacter sp, Klebsiella sp, Streptococcus sp, Escherichia coli and
Staphylococcus aureus. The peptides obtained from Streptomyces predominantly showed effective
antibacterial activities. The compost isolated actinomycetes mainly identified belonging to
Thermoactinomycetes, Micromonospora and Streptomyces also showed antibacterial activity but showed
good antiproliferative effect against the proliferative yeast cultured cell lines. The morphological features
of actinomycetes were characterized by gram staining, acid fast staining and slide culture techniques.