Key Laboratory of Saline-alkali Vegetation Ecology Restoration in Oil Field (SAVER), Ministry of Education, Alkali Soil Natural Environmental Science Center (ASNESC), Northeast Forestry University, Harbin Hexing Road, Harbin 150040, People's Republic of China.
World J Microbiol Biotechnol. 2012 May;28(5):2147-57. doi: 10.1007/s11274-012-1020-7. Epub 2012 Feb 14.
In northeast China there are large areas of nearly bare soda saline-alkali soil, in which plant survival is exteremely difficult because the land has a pH greater than 10.5. In order to obtain resistant microbial resources able to grow in such conditions, we analyzed environmental microbial samples from this extreme saline-alkali soil region. Through selective culture conditions, 8 bacterial strains were isolated from medium with no less than 1.5 M NaCl, 12 were isolated in the medium with a pH value of no less than 11.0, and 8 were isolated in the medium with of no less than 200 mM Na(2)CO(3). Based on 16S rRNA gene sequence analysis 20 novel strains of bacteria were identified and classified into four groups: 8 group I strains belong to the genus Bacillus; three group II belong to genus Nesterenkonia (2 strains) and genus Zhihengliuella (1 strain); eight group III strains belong to the genera Halomonas (6), Stenotrophomonas (1) and Alkalimonas (1); one group IV strain belongs to genus Litoribacter. These four groups belong to the phylum Firmicutes, phylum Actinobacteria, phylum Gamma-Proteobacteria and phylum Bacteroidetes, respectively. The sequence homology of 16S rRNA in strains ANESC-S, H.sp.C4 and H.sp.C6 with that of known strains was 93.2, 96.5 and 96.5%, respectively. Based on the 97.0% identity cutoff commonly used to discriminate bacterial species, our data suggest that H. sp.C4 and H.sp.C6 may be new species, and ANESC-S may be belong to a new genus of classified into order Cytophagales. The morphological characteristics by scanning electron microscopy (SEM) showed that, in addition to the coccal N.sp.N3, the majority (19) of the isolates are bacilli of various lengths. In culture the colonies appeared red, orange, yellow, light yellow, and milk-white, with milk-white being predominant. Based on the resistance to NaCl and pH, the 20 novel strains were classified into obligate alkaliphilic and halophilic bacteria, obligate alkaliphilic halotolerant bacteria, and facultative alkalophilic salt-tolerant bacteria. This is the first study reporting the isolation and characterization of bacterial resources from extreme saline-alkali soils from northeast China.
在中国东北，有大片几乎光秃秃的苏打盐碱土，由于土地的 pH 值大于 10.5，植物的生存极其困难。为了获得能够在这种条件下生长的抗微生物资源，我们从这个极端盐碱土地区分析了环境微生物样本。通过选择性培养条件，从含有不少于 1.5 M NaCl 的培养基中分离出 8 株细菌，从 pH 值不低于 11.0 的培养基中分离出 12 株，从不少于 200 mM Na(2)CO(3)的培养基中分离出 8 株。基于 16S rRNA 基因序列分析，鉴定出 20 株新的细菌菌株，并分为 4 组：8 株 I 组菌株属于芽孢杆菌属；3 株 II 组属于内斯彻恩科尼亚菌属（2 株）和志贺氏菌属（1 株）；8 株 III 组菌株属于盐单胞菌属（6 株）、寡养单胞菌属（1 株）和盐碱单胞菌属（1 株）；1 株 IV 组菌株属于利托比拉菌属。这 4 组分别属于厚壁菌门、放线菌门、γ-变形菌门和拟杆菌门。菌株 ANESC-S、H.sp.C4 和 H.sp.C6 的 16S rRNA 序列与已知菌株的同源性分别为 93.2%、96.5%和 96.5%。根据通常用于区分细菌种的 97.0%同一性截断值，我们的数据表明 H. sp.C4 和 H.sp.C6 可能是新种，而 ANESC-S 可能属于一个新的分类目 Cytophagales。扫描电子显微镜（SEM）的形态特征表明，除了球菌 N.sp.N3 外，大多数（19）分离株都是各种长度的杆菌。在培养过程中，菌落呈红色、橙色、黄色、浅黄色和乳白色，以乳白色为主。根据对 NaCl 和 pH 的抗性，20 株新菌株分为专性嗜碱菌和嗜盐菌、专性嗜碱耐盐菌和兼性嗜碱耐盐菌。这是首次报道从中国东北极端盐碱土中分离和鉴定细菌资源的研究。
