Sriragavi Govindaraj, Sangeetha Murthy, Santhakumar Munusamy, Lokesh Elumalai, Nithyalakshmi Mohanam, Saleel Chanduveetil Ahamed, Balagurunathan Ramasamy
Actinobacterial Research Laboratory, Department of Microbiology, Periyar University, Salem 636011, Tamilnadu, India.
Department of Mechanical Engineering, College of Engineering, King Khalid University, P.O. Box 394, Abha 61421, Saudi Arabia.
ACS Omega. 2023 Sep 22;8(39):36333-36343. doi: 10.1021/acsomega.3c04954. eCollection 2023 Oct 3.
The increasing concern over multidrug resistance in pathogens has led to an ongoing search for novel antibiotics derived from soil actinobacteria. In this current investigation, actinobacteria were isolated from the rhizosphere of bamboo plants collected within the Megamalai forest of the Western Ghats in the Theni zone of Tamil Nadu, India. These actinobacteria were subjected to characterization, and their growth conditions were optimized to enhance the production of bioactive compounds. To assess antibacterial properties, the isolated Actinobacteria underwent testing using the agar plug method. The strain exhibiting notable antibacterial activity underwent further characterization through 16s rRNA gene sequencing and subsequent phylogenetic analysis. Employing response surface methodology (RSM), cultural conditions were fine-tuned. Bioactive compounds were extracted from the culture medium using ethyl acetate, and their antibacterial and antioxidant effects were evaluated through disc diffusion and DPPH radical scavenging methods, respectively. Ethyl acetate extracts were analyzed by using FT-IR and GC-MS techniques. In total, nine strains of Actinobacteria were isolated from the rhizosphere soil of bamboo. Among these, strain BS-16 displayed remarkable antibacterial activity against three strains: (19 mm), (12 mm), and (10 mm). This strain was identified as sp. The optimal conditions for bioactive compound production were determined as follows: malt extract (10 g), yeast extract (5 g), dextrose (5 g), pH 6.5, and temperature 30 °C. After a 7-day incubation period, the results showed a 6% increase in production. The ethyl acetate fraction derived from strain BS-16 exhibited dose-dependent antibacterial and antioxidant activities. FT-IR and GC-MS analyses revealed the presence of active compounds with antibacterial effects within the extract. Consequently, further investigation into the BS-16 strain holds promise for scaling up the production of bioactive compounds possessing antibacterial and antioxidant properties.
对病原体中多重耐药性的日益关注促使人们不断寻找源自土壤放线菌的新型抗生素。在本次研究中，从印度泰米尔纳德邦特尼区西高止山脉梅加马莱森林采集的竹类植物根际中分离出放线菌。对这些放线菌进行了表征，并优化了它们的生长条件以提高生物活性化合物的产量。为了评估抗菌性能，使用琼脂块法对分离出的放线菌进行测试。对表现出显著抗菌活性的菌株通过16s rRNA基因测序及后续系统发育分析进行进一步表征。采用响应面法（RSM）对培养条件进行微调。使用乙酸乙酯从培养基中提取生物活性化合物，并分别通过纸片扩散法和DPPH自由基清除法评估其抗菌和抗氧化作用。通过傅里叶变换红外光谱（FT-IR）和气相色谱-质谱联用（GC-MS）技术对乙酸乙酯提取物进行分析。总共从竹根际土壤中分离出9株放线菌。其中，菌株BS-16对三种菌株表现出显著的抗菌活性：（19毫米）、（12毫米）和（10毫米）。该菌株被鉴定为链霉菌属。确定生物活性化合物生产的最佳条件如下：麦芽提取物（10克）、酵母提取物（5克）、葡萄糖（5克）、pH值6.5和温度30℃。经过7天的培养期，结果显示产量增加了6%。源自菌株BS-16的乙酸乙酯级分表现出剂量依赖性的抗菌和抗氧化活性。FT-IR和GC-MS分析表明提取物中存在具有抗菌作用的活性化合物。因此，对BS-16菌株的进一步研究有望扩大具有抗菌和抗氧化特性的生物活性化合物的生产规模。
