Department of Biological Sciences, Birla Institute of Technology and Science Pilani, K K Birla Goa Campus, Zuarinagar, Goa, India.
J Appl Microbiol. 2013 May;114(5):1347-56. doi: 10.1111/jam.12135. Epub 2013 Feb 13.
Characterization of polyhydroxyalkanoates (PHA) accumulated by halophilic bacteria isolated from solar salterns.
Twenty-six halophilic isolates were obtained from solar salterns of Goa, India. They were screened for accumulation of PHA by Sudan black B, Nile blue A and Nile red stains. Strains H15, H16 and H26 were selected based on their intensity of Nile blue A/Nile red fluorescence. On the basis of phenotypic and genotypic characterization, the three isolates were identified as Bacillus megaterium. Growth kinetics and polymer accumulating capacity of strain H16 were studied in E2 mineral media with 2% glucose with/without NaCl. In the absence of NaCl, strain H16 accumulated PHA to 40·0% (w/w) of cell dry weight (CDW) at 42 h of growth, whereas in presence of 5% w/v NaCl, the culture showed longer lag phase of up to 24 h and accumulated a maximum PHA of 39% (w/w) CDW at 54 h of growth. The infrared spectra of both the polymers exhibited peaks at 1733·9 cm(-1) characteristic of C=O. Scans of (1) H nuclear magnetic resonance (NMR) showed a doublet at 2·5 ppm corresponding to methylene group (-CH(2)), the signal at 5·3 ppm corresponded to methine group (-CH-), and another signal at 1·3 ppm corresponded to the methyl group (-CH(3)). Scans of (13)C NMR showed prominent peaks at 20, 40, 67-68 and 170 ppm, indicating the polymer to be homopolymer of 3-hydroxybutyrates. The polymer is stable up to a temperature of 160°C.
Three moderately halophilic isolates (strain H15, H16 and H26) capable of accumulating PHA were isolated from solar salterns of Ribandar Goa, India, and identified as B. megaterium based on phenotypic and genotypic characterization. Strain H16 accumulated polyhydroxybutyrate in the presence and absence of NaCl up to 40% of its CDW.
This strain would be better suited for production of PHA at industrial level due to its tolerance to high concentration of NaCl.
对从印度果阿盐田分离出的嗜盐菌积累的聚羟基烷酸（PHA）进行表征。
从印度果阿盐田获得了 26 株嗜盐菌。用苏丹黑 B、尼罗蓝 A 和尼罗红染色法筛选 PHA 的积累。根据尼罗蓝 A/尼罗红荧光的强度，选择菌株 H15、H16 和 H26。基于表型和基因型特征，这三种分离物被鉴定为巨大芽孢杆菌。在 E2 矿物培养基中，用 2%葡萄糖和/或 5%w/v NaCl 研究了菌株 H16 的生长动力学和聚合物积累能力。在没有 NaCl 的情况下，菌株 H16 在 42 小时的生长过程中积累了 40.0%（w/w）的细胞干重（CDW）的 PHA，而在存在 5%w/v NaCl 的情况下，培养物表现出长达 24 小时的较长迟滞期，在 54 小时的生长过程中积累了 39%（w/w）的 CDW 的 PHA。两种聚合物的红外光谱均在 1733.9 cm(-1)处显示出 C=O 的特征峰。（1）H 核磁共振（NMR）图谱显示 2.5 ppm 处的双峰对应于亚甲基（-CH(2)），5.3 ppm 处的信号对应于次甲基（-CH-），1.3 ppm 处的另一个信号对应于甲基（-CH(3)）。（13）C NMR 图谱显示 20、40、67-68 和 170 ppm 处的显著峰，表明聚合物为 3-羟基丁酸的均聚物。该聚合物在高达 160°C 的温度下稳定。
从印度果阿里班达尔盐田分离出了三株能够积累 PHA 的中度嗜盐菌（菌株 H15、H16 和 H26），并根据表型和基因型特征鉴定为巨大芽孢杆菌。菌株 H16 在有和没有 NaCl 的情况下将聚羟基丁酸积累到其 CDW 的 40%。
由于该菌株对高浓度 NaCl 的耐受性，因此更适合于工业水平生产 PHA。
