Mandragutti Teja, Sudhakar G
Department of Biotechnology, Andhra University, Visakhapatnam, 530003, India.
Department of Human Genetics, Andhra University, Visakhapatnam, India.
J Genet Eng Biotechnol. 2023 Feb 28;21(1):24. doi: 10.1186/s43141-023-00484-y.
Biopolymers like polyhydroxyalkanoates (PHA) are the best natural macromolecules to use as alternative to the synthetic polymers. Many prokaryotes accumulate PHA as cytoplasmic intracellular granules and their accumulation is triggered by starving conditions. The PHAs are ecofriendly and used to create biodegradable plastics. The microbial synthesized PHA had acquired global importance in industrial and biomedical sectors.
Ten different bacterial strains were isolated for the screening of PHA producers from the estuarine region of the Bay of Bengal, Suryalanka in Bapatla. A yellowish slimy circular colony known as M4 is actively growing on selective minimal media and was screened for polymeric granules in its cytoplasm using Sudan Black B and confirmed with the fluorescent dye Nile blue A. All of the isolates were biochemically tested and isolate M4 is the most capable of growing at high NaCl concentrations (3.2 percent) and tests positive for catalase, methyl red. The M4 strain revealed clear hydrolysis of gelatin, starch, and casein. The 16S rRNA sequencing revealed that M4 is 99.72% of identity to Brachybacterium paraconglomeratum LMG 19861(T) in BLAST and the obtained strain was assigned with accession no. MTCC 13074 and deposited in NCBI with accession no. MW899045. The chief cellular fatty acids found in M4 were C14:0, C15:0, C16:0, C18:1cis-9, C18:0, iso-C15: 0, iso-C14: 0, anteiso-C17: 0 and C18:1-7. Crotonic acid formation from M4-PHB extract was detected at 235nm in a UV spectrophotometer. Methanolysis was done, and derivatives of polyhydroxybutyric acid (PHB) in the extract were analyzed using GC-MS. Increasing viscosity was seen in the extracts which confirms the presence of polymer in the extracts. Thermogravimetric analysis was studied to determine the thermal profile of the PHB in the extract of M4.
In the study, the selective screening and extraction of ecofriendly PHB from M4 strain was highlighted. Brachybacterium paraconglomeratum is a novel strain showed its uniqueness by producing few monomeric derivatives of PHB. The strain was reporting for the first time as PHA producer. B. paraconglomeratum has promising characteristics according to its metabolic profile. In addition, this study also helps to understand the diversity of bacteria isolated from marine sources.
聚羟基脂肪酸酯（PHA）等生物聚合物是替代合成聚合物的最佳天然大分子。许多原核生物将PHA积累为细胞质内的颗粒，饥饿条件会触发其积累。PHA对环境友好，可用于制造可生物降解的塑料。微生物合成的PHA在工业和生物医学领域已具有全球重要性。
从巴帕特拉苏里亚兰卡孟加拉湾河口地区分离出10种不同的细菌菌株，用于筛选PHA生产者。一种名为M4的淡黄色粘性圆形菌落在选择性基本培养基上活跃生长，使用苏丹黑B对其细胞质中的聚合物颗粒进行筛选，并用荧光染料尼罗蓝A进行确认。对所有分离株进行了生化测试，分离株M4最能在高NaCl浓度（3.2%）下生长，过氧化氢酶、甲基红测试呈阳性。M4菌株对明胶、淀粉和酪蛋白有明显的水解作用。16S rRNA测序显示，M4在BLAST中与副凝聚短杆菌LMG 19861(T)的同一性为99.72%，所获得的菌株被赋予登录号MTCC 13074，并在NCBI上以登录号MW899045保存。在M4中发现的主要细胞脂肪酸为C14:0、C15:0、C16:0、C18:1顺式-9、C18:0、异-C15:0、异-C14:0、反异-C17:0和C18:1-7。在紫外分光光度计中于235nm处检测到M4-PHB提取物中产生巴豆酸。进行了甲醇解，并使用气相色谱-质谱联用仪分析了提取物中聚羟基丁酸（PHB）的衍生物。提取物的粘度增加，证实提取物中存在聚合物。研究了热重分析以确定M4提取物中PHB的热谱。
本研究重点突出了从M4菌株中选择性筛选和提取环境友好型PHB。副凝聚短杆菌是一种新型菌株，通过产生少量PHB单体衍生物显示出其独特性。该菌株首次作为PHA生产者被报道。根据其代谢谱，副凝聚短杆菌具有良好的特性。此外，本研究还有助于了解从海洋来源分离的细菌的多样性。
