Actinomycetes are the source of many secondary metabolites, enzymes, and antimicrobials that have various applications. This study aimed to evaluate the photostimulatory effect of UV and laser light on the lipase, amylase and antimicrobial productivity of three actinomycetes' strains from genera: Micromonospora, Pseudonocardia, and Nocardiopsis. The strains were exposed to UV (300-400 nm) and monochromatic laser (632.8 nm) radiations for 10 and 20 minutes. The influence of radiations on the actinomycetes' growth, pigment production, enzymatic and antimicrobial activity was evaluated after incubation at 28 ±2 °C for 7 days. Two reference bacterial strains Escherichia coli NCMB 11943 and Staphylococcus aureus NCMB 6571, and one clinical yeast strain Candida albican, were used for antibacterial assessment, compared to five commercial antibiotics.

Both Pseudonocardia and Micromonospora have exhibited significant increase in pigmentation with laser exposure. In contrast, Nocardiopsis has shown reduction in pigment production. The UV and Laser radiations have almost doubled the amylase enzyme activity in Pseudonocardia and Micromonospora strains, while not affecting lipase production. On the other hand, the crude metabolites from the Micromonospora sp. strain exhibited a highly promising inhibitory effect against E. coli (NCMB11943) when compared with five commercially available antibiotics. The laser irradiation for 10 min has almost doubled the inhibitory zone of Micromonospora metabolites against S. aureus (from 0.65 to 1.2 cm) and C. albicans (from 0.7 to 1.3 cm). In conclusion, the results of our research recommend using monochromatic laser radiation to enhance the production of amylase and antimicrobial metabolites from Pseudonocardia and Micromonospora, respectively.