Marine macroalgae and their accompanying microbial flora were proved to be the reservoir of potential bioactive compounds with promising pharmacological applications. Heterotrophic bacteria concomitant with the marine algae were isolated and screened for their antibacterial potential against clinically recognized pathogens. The bacterial isolate with greater bioactive properties was identified as Bacillus velezensis MBTDLP1 (phylum Firmicutes), which was isolated from the marine macroalga Laurencia papillosa, by integrated morphological, biochemical and molecular characterization. B. velezensis showed promising antibacterial property against methicillin-resistant Staphylococcus aureus and Vibrio parahemolyticus with inhibition zone of 32-36 mm. Organic ethyl acetate extract of the isolate also displayed prospective antibacterial activity against the test pathogens (minimum inhibitory concentration 7.5-15 µg/mL), coupled with promising antioxidant (IC50 0.1-0.9 mg/mL against oxidants), anti-inflammatory (IC50 0.01 mg/mL against 5-lipoxygenase), and carbolytic enzyme attenuation properties (IC50 0.1-0.4 mg/mL in response to α-amylase and α-glucosidase). Significant anticancer potential against breast carcinoma (MCF-7) cells (IC50 0.03 mg/mL) coupled with lesser cytotoxicity to the normal fibroblast (3T3L) cells (IC50 0.14 mg/mL) were also recognized. The apoptosis assay could give reasonable outcome as the organic extract of B. velezensis induced apoptosis to 81% of the cancer cells while maintaining almost 60% viability in normal cells. The results put forward that B. velezensis MBTDLP1 could be used to isolate bioactive compounds with therapeutic potential and biomedical applications.

中文翻译：

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海洋巨藻相关异养芽孢杆菌作为前瞻性治疗剂

海洋大型藻类及其伴随的微生物群被证明是具有潜在药理学应用前景的生物活性化合物的储存库。与海藻共生的异养细菌被分离出来，并筛选了它们对临床公认的病原体的抗菌潜力。具有更大生物活性特性的细菌分离物被鉴定为 Bacillus velezensis MBTDLP1（厚壁菌门），它是从海洋巨藻 Laurencia papillosa 中分离出来的，通过综合形态学、生化和分子表征。B. velezensis 对耐甲氧西林金黄色葡萄球菌和副溶血性弧菌显示出良好的抗菌性能，抑菌圈为 32-36 mm。分离物的有机乙酸乙酯提取物也显示出对测试病原体的预期抗菌活性（最低抑制浓度 7.5-15 µg/mL），加上有希望的抗氧化剂（IC50 0.1-0.9 mg/mL，抗氧化剂），抗炎（IC50 0.01 mg/mL 对 5-脂氧合酶）和碳化酶衰减特性（IC50 0.1-0.4 mg/mL 对 α-淀粉酶和α-葡萄糖苷酶的反应）。还认识到对乳腺癌 (MCF-7) 细胞的显着抗癌潜力 (IC50 0.03 mg/mL) 以及对正常成纤维细胞 (3T3L) 细胞的较小细胞毒性 (IC50 0.14 mg/mL)。由于 B. velezensis 的有机提取物诱导了 81% 的癌细胞凋亡，同时在正常细胞中保持了近 60% 的活力，因此细胞凋亡测定可以给出合理的结果。结果表明 B.