Antibacterial, cytotoxic and antioxidant activities, and identification of bioactive volatile compounds from Streptomyces sp. LV20 isolated from sediments of Lago Verde, Alter do Chão, Amazonia, Brazil.

One of the major public health challenges is pathogen resistance to multiple drugs, leading to intensive searches for new antimicrobial agents from natural sources through the exploration of new niches. The objective of this research was to isolate actinobacteria from sediments of Lago Verde (Green Lake) in Alter do Chão, evaluating their antibacterial, cytotoxic, and antioxidant activities, and identifying their bioactive volatile compounds. Identification was carried out through morphological and biochemical evaluation. Antibacterial activity was investigated using the agar disk diffusion method against 17 pathogens of clinical interest. Cytotoxic activity was determined by the percentage inhibition of cell growth in samples of the human colorectal carcinoma cell line HCT116, using a concentration of 10 µg/mL, with results expressed as mean ± SEM (n=2). The determination of antioxidant activity was performed using the DPPH radical scavenging assay. The volatile compound profile of the crude extract was established through gas chromatography-mass spectrometry (GC-MS) analysis. The identification of isolate LV20 shows characteristics of the phylum Actinobacteria, suggestive of the genus Streptomyces. Its antibacterial activity demonstrated action against Staphylococcus epidermidis (17.75 ± 1.25 mm) and Enterococcus faecalis (17.5 ± 0.5 mm), as well as inhibiting the proliferation of the HCT116 tumor cell line by 95.55%. The crude ethyl acetate extract of LV20 showed significant antioxidant activity by the DPPH method, evidenced by an Effective Concentration (EC50) of 890.29 µg/mL. Chromatographic analysis identified bioactive volatile compounds, notably glycerin (28%), tris(2,4-di-tert-butylphenyl) phosphate (22.12%), and benzenepropanoic acid, 3,5-bis(1,1-dimethylethyl)-4-hydroxy-, octadecyl ester (14.67%), which exhibit pharmacological potential. The novel results demonstrate the biological variability of Streptomyces sp. LV20 as a promising source of bioactive molecules with therapeutic applications, highlighting the importance of Amazonian biodiversity for the bioprospecting of new drugs.