茶园土壤耐酸铝微生物的分离鉴定及其耐铝特性研究

Isolation and characterization of acid-and Al-tolerant microorganisms.

对茶园土壤中耐酸铝微生物进行分离纯化,并选择其中的3株真菌,用通用引物NS1和NS8PCR扩增出全长18S rDNA基因,测序后与GenBank数据库中的相似序列构建系统发育树,结合真菌形态分析,初步鉴定为:Aspergillus zonatus,Penicilliumsp.和Rhizopussp..他们都具有很强的耐酸铝特性,其中F2株甚至可以在200 mmol·L-1的Al3+、pH2.2的条件下生长.在pH3.5的琼脂平板培养基上,铝对3株真菌生长速率的影响总体表现为:随Al3+浓度的增加而下降,其中F6株较为明显,而低浓度的铝(10 mmol·L-1)对F2株生长有一定促进作用.在pH3.5的土壤提取液培养基(S-LB)中培养7d后,3株真菌的培养液pH均升高到7.0左右,铝的含量也由于pH的升高而降低;在含1.0%葡萄糖的土壤提取液培养基中,培养液pH却降低到2.7左右,并且铝的含量几乎没有变化.这些结果揭示了分离的真菌可能具有不同的耐酸铝机制.

Acid- and aluminum （Al）-tolerant microorganisms were isolated from acidic tea fields, from which three fungal strains were selected and identified as Aspergilluz zonatus, Penicillium sp. and Rhizopus sp. by molecular phylogenetic trees based on 18S rDNA gene sequences and morphological characteristic analysis, They were tolerant to Al^3＋ up to 100-200 mmol · L^-1 and could grow at low pH. F2 strain even could grow at pH2. 2, 200 mmol· L^-1 Al^3＋. Generally, the growth rates showed decreasing trends with the increasing concentration of Al^3＋ when the microorganisms were cultured on agar plate with pH3. 5. However, the low concentration of Al^3＋ may accelerate the growth of F2 strain, In a soil extract medium （pH3. 5）, pH of the spent medium of all strains increased to around 7.0 and Al^3＋ content in the spent medium decreased due to the increase of pH. When put 1.0% glucose into the soil extract medium, pH of the spent medium decreased to 2.7, Al^3＋ content in the spent medium almost remained constant. These results suggested that the fungi isolated possibly have different acid- and Al-tolerant mechanisms.