Abstract
Lake Mariout is Egypt’s degraded coastal marine habitat that encompasses a variety of wastes. The biodiversity and hard environmental conditions allow the co-existence of organisms with high resistance and rich metabolism, making them potential candidates for screening and isolating novel microbial strains. A bacterial isolate (BF202) cultured from the marine sediments of Alexandria’s Mariout Lake (Egypt) was tested for its antimicrobial and anticancer potential. The phylogenetic analysis of the isolated strain’s
16S rDNA
and
gyrB
revealed that BF202 belongs to
Brevibacillus laterosporus
(
B. laterosporus
). Antibiosis of
B. laterosporus
was confirmed against microbial pathogens including
Escherichia coli, Klebsiella pneumoniae
,
Salmonella typhi
, and
Staphylococcus aureus
. The highest antibacterial activity was detected on glucose peptone medium after 18 h of incubation at 35 °C, and at pH of 7.0 in the presence of mannose and ammonium carbonate as carbon and nitrogen sources, respectively. The cytotoxicity of the methanolic extract against breast cancer (MCF-7) and normal Vero cell lines, using the MTT test, revealed IC
50
values of 7.93 and 23.79 µg/mL, respectively. To identify apoptotic and necrotic cells, a flow cytometric analysis using annexin V-FITC/PI dual-labeling was utilized and recorded a higher number of necrotic cells compared to apoptotic ones. Similarly, the cell cycle S-phase arrest was reported. The LC-MS-MS investigation of
B. laterosporus
extract and the molecular networking database analysis demonstrated five strategic diketopiperazine compounds with antimicrobial and anticancer activities. Taken together, this research shows that the crude extract of
B. laterosporus
might be an effective agent against drug-resistant bacteria and malignant disorders due to its richness in diketopiperazines.