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首页> 外文期刊>Current Science: A Fortnightly Journal of Research >Characterization of polyhydroxy alkanoates - Biodegradable plastics from marine bacteria
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Characterization of polyhydroxy alkanoates - Biodegradable plastics from marine bacteria

机译：多羟基链烷酸酯的表征-海洋细菌可生物降解的塑料

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A wide variety of bacteria accumulate polyhydroxy alkanoates (PHAs) as intracellular storage material. Because of their physical and structural properties and amenability to biodegradation, PHAs are considered potential substitutes for petrochemical plastics. PHAs vary in their mechanical properties depending on the composition of the monomeric units. The medium chain-length PHAs are semi-crystalline elastomers with a low melting point (T_m), low tensile strength and high elongation to break, and can be used as biodegradable rubber. Polyhydroxy butyrate (PHB), smallest known PHA displays a similar degree of crystallinity and T_m as polystyrene8, and is stiffer and more brittle than polypropylene; but its copolymerization with hydroxy valerate (HV) monomer units reduces its stiffness and increases its toughness, giving a product with desirable properties for commercial applications. Polymers may fail in specific applications, simply because they do not possess the necessary strength to carry the designed load or occasional overload. Hence, it is important to study the mechanical and physical properties of such commercially important polymers before their use in the industry. Tropical mangrove and marine ecosystems from the mid-west coast of India were screened for promising bacteria, with capability of accumulating high amounts of PHA. The isolates designated as 61/4, 64/4, 87/4, 182/5, 12/BL, 85/6 and 86/6, which accumulated more than one gram PHA per litre culture broth were studied for physico-chemical factors influencing quantitative yield of PHA (unpublished results). The physical and mechanical properties of the PHA produced by these organisms are presented here.
机译：多种细菌积累多羟基链烷酸酯（PHA）作为细胞内存储材料。由于其物理和结构特性以及易于生物降解的特性，PHA被认为是石化塑料的潜在替代品。 PHA的机械性能取决于单体单元的组成。中等链长的PHA是具有低熔点（T_m），低拉伸强度和高断裂伸长率的半结晶弹性体，可以用作可生物降解的橡胶。聚羟基丁酸酯（PHB）是已知最小的PHA，其结晶度和T_m与聚苯乙烯8相似，并且比聚丙烯更硬，更脆。但是它与戊酸羟基酯（HV）单体单元的共聚作用降低了其刚度并提高了其韧性，从而为产品提供了具有商业用途所需的性能。聚合物在特定的应用中可能会失效，这仅仅是因为它们不具备承受设计载荷或偶尔过载的必要强度。因此，重要的是在工业上使用这种商业上重要的聚合物之前研究其机械和物理性能。对印度中西部沿海的热带红树林和海洋生态系统进行了筛选，筛选出有前途的细菌，这些细菌具有积累大量PHA的能力。研究了每升培养液中积累超过1克PHA的61 / 4、64 / 4、87 / 4、182 / 5、12 / BL，85/6和86/6菌株的理化因子影响PHA的定量产量（未发表的结果）。这些生物体产生的PHA的物理和机械特性在此介绍。

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