Abstract:
Exploring untapped microbial potentials in previously uncharted
environments has become crucial in discovering novel secondary
metabolites and enzymes for biotechnological applications. Among
prokaryotes, actinomycetes are well recognized for producing a vast
range of secondary metabolites and extracellular enzymes. In the
present study, we have used surface sediments from ‘Kadolkele’
mangrove ecosystem located in the Negombo lagoon area, Sri
Lanka, to isolate actinomycetes with bioactive potentials. A total
of six actinomycetes were isolated on modified-starch casein agar
and characterized. The isolates were evaluated for their antibacterial
activity against four selected bacterial strains and to produce
extracellular enzymes: cellulase, amylase, protease, and lipase. Three
out of the six isolates exhibited antibacterial activity against Staphylococcus
aureus, Escherichia coli, and Bacillus cereus, but not against
Listeria monocytogenes. Five strains could produce extracellular cellulase,
while all six isolates exhibited amylase activity. Only three
of the six isolates were positive for protease and lipase assays separately.
Ac-1, Ac-2, and Ac-9, identified as Streptomyces spp. with the
16S rRNA gene sequencing, were used for pigment extraction using
four different solvents. Acetone-extracted crude pigments of Ac-1
and Ac-2 were further used in well-diffusion assays, and growth
inhibition of test bacteria was observed only with the crude pigment
extract of Ac-2. Further, six different commercially available
fabrics were dyed with crude pigments of Ac-1. The dyed fabrics
retained the yellow color after acid, alkaline, and cold-water treatments
suggesting the potential of the Ac-1 pigment to be used in
biotechnological applications.
