天山1号冰川前缘土壤中光合细菌的分离鉴定及氮转化能力分析

Isolation, Identification and Analysis of Nitrogen Transformation Ability of Photosynthetic Bacteria in Deglaciated Forelands of Tianshan Mountain No.1 Glacier

【目的】分离,鉴定冰川前缘原生裸地土壤中紫色非硫光合细菌,并且对其氮转化能力进行分析。【方法】采用紫色非硫光合细菌富集培养基从天山1号冰川前缘土壤中富集,分离紫色非硫光合细菌,纯化后的单菌落采用形态学观察和基于16S rRNA测序的分子生物学进行鉴定。对分离得到的菌株其对氨氮和硝态氮转化能力动态变化进行为期15 d的监测。【结果】通过富集培养共分离得到5株光合细菌,活细胞吸收峰检测结果显示这几株菌在480、510、590和810 nm处有明显吸收峰;菌株最适生长pH为7.0。分子生物学鉴定4株为类球红杆菌(命名1Y, 241, GZ, G6),1株为沼泽红假单胞菌(LG)。菌株LG对氨态氮的转化率最高为65.71%,菌株GZ为56.22%次之,其余转化率为53%左右。菌G6对硝态氮的转化率最高能够达到95.79%,其次是菌株LG为95.58%,最弱的是菌株241为69.96%。并且,经光合细菌转化后的硝态氮和铵态氮仅有2%左右转化为亚硝酸盐,其余均转化为菌体蛋白。【结论】光合细菌能够高效地将无机氮转化为有机氮,其对于贫瘠土壤中氮素的固定和高效利用可能具有重要意义。

【Objective】This paper aimed to isolate,purify and identify PSB in soils of glacier foreland and analyze their nitrogen conversion ability.【Method】PSB was enriched by the enrichment medium and isolated from the soils of the glacial front of Mt.Tianshan No.1.The pu-rified single colonies were observed by morphological observation and their identification were detected by molecular biology based on 16S rRNA gene sequencing.The dynamic changes of ammonia and nitrate nitrogen degradation by the PSB were monitored for 15 days,and the residue nitrogen and the transformed nitrite contents were also documented.【Results】Five PSB were isolated based on their different growth rate,the absorption peaks of those living cells showed obvious absorption peaks at 480,510,590 and 810 nm,and the optimal growth pH of the strain was 7.0.Phylogenetic analysis showed that four strains(named 1Y,241,GZ and G6,respectively)were divided into Rhodobactersphaeroides with>99%of 16S rRNA gene similarity,and one strain was classified into Rhodopseudomonaspalustris with 100%of the gene similarity(named LG).Among them,the ammonia nitrogen conversion rate of strain LG were 65.71%,the strain GZ was 56.22%,and the others reached 53%.The nitrate conversion rate of strain G6 reached 95.79%,followed by strain LG(95.58%),and the weakest was strain 241(69.96%).After PSB conversion,most of the ammonia and nitrate were transformed into mycoprotein and 2%of nitrite were produced【Conclusion】PSB would transform inorganic nitrogen into organic nitrogen with high efficiency,suggesting it had an important significance in nitrogen fixation and nitrogen highly usage in nutrient-poor soils.