Shri AMM Murugappa Chettiar Research Center (MCRC), Taramani, Chennai, 600113, India.
Arch Microbiol. 2011 Aug;193(8):543-52. doi: 10.1007/s00203-011-0691-z. Epub 2011 Mar 29.
Thirteen pink-pigmented facultative methylotrophic (PPFM) strains isolated from Adyar and Cooum rivers in Chennai and forest soil samples in Tamil Nadu, India, along with Methylobacterium extorquens, M. organophilum, M. gregans, and M. komagatae were screened for phosphate solubilization in plates. P-solubilization index of the PPFMs grown on NBRIP-BPB plates for 7 days ranged from 1.1 to 2.7. The growth of PPFMs in tricalcium phosphate amended media was found directly proportional to the glucose concentration. Higher phosphate solubilization was observed in four strains MSF 32 (415 mg l(-l)), MDW 80 (301 mg l(-l)), M. komagatae (279 mg l(-l)), and MSF 34 (202 mg l(-l)), after 7 days of incubation. A drop in the media pH from 6.6 to 3.4 was associated with an increase in titratable acidity. Acid phosphatase activity was more pronounced in the culture filtrate than alkaline phosphatase activity. Adherence of phosphate to densely grown bacterial surface was observed under scanning electron microscope after 7-day-old cultures. Biochemical characterization and screening for methanol dehydrogenase gene (mxaF) confirmed the strains as methylotrophs. The mxaF gene sequence from MSF 32 clustered towards M. lusitanum sp. with 99% similarity. This study forms the first detailed report on phosphate solubilization by the PPFMs.
十三株从印度钦奈的 Adyar 和 Cooum 河以及泰米尔纳德邦的森林土壤样本中分离出的粉色可培养兼性甲基营养型（PPFM）菌株，与 Methylobacterium extorquens、M. organophilum、M. gregans 和 M. komagatae 一起，在平板上筛选了磷酸盐溶解能力。在 NBRIP-BPB 平板上培养 7 天后，PPFMs 的磷溶解指数范围为 1.1 至 2.7。发现 PPFMs 在添加磷酸三钙的培养基中的生长与葡萄糖浓度直接成正比。在 7 天的培养后，发现四种菌株 MSF 32（415mg l(-1)）、MDW 80（301mg l(-1)）、M. komagatae（279mg l(-1)）和 MSF 34（202mg l(-1)）具有更高的磷酸盐溶解能力。培养基 pH 值从 6.6 下降到 3.4 与可滴定酸度的增加有关。在培养滤液中，酸性磷酸酶活性比碱性磷酸酶活性更为明显。在 7 天龄的培养物下，在扫描电子显微镜下观察到磷酸盐附着在密集生长的细菌表面上。生化特性和甲醇脱氢酶基因（mxaF）的筛选证实了这些菌株是甲基营养型的。MSF 32 的 mxaF 基因序列与 M. lusitanum sp. 聚类，相似度为 99%。这项研究首次详细报道了 PPFMs 的磷酸盐溶解能力。
