Singh Purnima, Hanada Yuichi, Singh Shiv Mohan, Tsuda Sakae
Birla Institute of Technology and Science (BITS), Goa campus, Zuarinagar, Goa, India.
FEMS Microbiol Lett. 2014 Feb;351(1):14-22. doi: 10.1111/1574-6968.12345. Epub 2013 Dec 18.
Fourteen Arctic bacterial strains belonging to five genera, Cryobacterium, Leifsonia, Polaromonas, Pseudomonas, and Subtercola isolated from sediments found in cryoconite holes of Arctic glaciers, were subjected to screening for antifreeze proteins (AFPs). Eight strains showed AFP activity, and six strains of four species were further characterized. Pseudomonas ficuserectae exhibited a high thermal hysteresis (TH) activity. Ice recrystallization inhibition (IRI) activity was observed in most cultures at low protein concentration. Bacterial AFPs produced rounded shape of ice crystals that did not change their size and morphology within the TH window. Cry-g (P. ficuserectae) failed to inhibit ice recrystallization, indicating that the IRI activity of the AFPs does not relate to the strength of TH activity. SDS-PAGE analysis of the AFPs suggests their apparent molecular weights to be around 23 kDa. This study is significant as it screens several species of Arctic bacterial strains for AFP activity. So far, only one species of bacteria, Pseudomonas putida, was reported from the Arctic to produce AFPs. N-terminal amino acid sequence analysis shows that the bacterial AFPs isolated belong to the AFP family IBP-1, which is known to have an important physiological role in the cold environment. AFPs of glacier cryoconite habitat have been discussed.
从北极冰川冰尘洞沉积物中分离出的属于5个属（嗜冷杆菌属、利夫松氏菌属、极地单胞菌属、假单胞菌属和地下杆菌属）的14株北极细菌菌株，接受了抗冻蛋白（AFP）筛选。8株菌株显示出AFP活性，对4个物种的6株菌株进行了进一步表征。榕生假单胞菌表现出高热滞（TH）活性。在大多数培养物中，低蛋白浓度时观察到冰重结晶抑制（IRI）活性。细菌AFP产生圆形冰晶，在TH窗口内其大小和形态不变。Cry-g（榕生假单胞菌）未能抑制冰重结晶，表明AFP的IRI活性与TH活性强度无关。AFP的SDS-PAGE分析表明其表观分子量约为23 kDa。这项研究意义重大，因为它筛选了几种北极细菌菌株的AFP活性。到目前为止，北极地区仅报道过一种细菌——恶臭假单胞菌能产生AFP。N端氨基酸序列分析表明，分离出的细菌AFP属于AFP家族IBP-1，已知该家族在寒冷环境中具有重要生理作用。本文还讨论了冰川冰尘栖息地的AFP。
