两株采自惠州的细鞘丝藻亚科(Leptolyngbyaceae)嗜热蓝细菌的分离鉴定及细胞组分分析

Isolation and characterization of two thermophilic Leptolyngbyaceae strains isolated from Huizhou area, China

摘要:

【背景】随着CO2排放增加，全球变暖愈发严峻，嗜热蓝细菌作为能够在45 °C及以上环境中生长并实现生物固碳的微生物，具有重要的研究意义。【目的】对从广东惠州地区采集的藻种进行分离鉴定，并筛选出2株嗜热蓝细菌，研究其生长特性，为嗜热蓝细菌的后续应用提供依据。【方法】通过16S rRNA基因、藻蓝蛋白链A基因(PhycoA)序列分析确定从惠州地区采集到的菌株的分类学位置。对PKUAC-GDTS1-24和PKUAC-GDTS1-29两株嗜热蓝细菌进行形态观察和主要细胞成分(灰分、糖类、脂质、蛋白质和色素)分析。【结果】共分离出12株嗜热蓝细菌，其中PKUAC-GDTS1-24和PKUAC-GDTS1-29菌株，形态上呈蓝绿色球形毛状体，是由细胞形成密集的簇，彼此附着形成的。两株嗜热蓝细菌的主要细胞成分是糖类，分别占细胞干重的36.42%和28.46%。PKUAC-GDTS1-24的灰分、脂质和蛋白质含量分别为24.41%、21.40%和26.64%。PKUAC-GDTS1-29的细胞中，灰分、脂质和蛋白质含量分别为24.72%、23.92%和12.93%。藻蓝蛋白(Phycocyanin，PC)在PKUAC-GDTS1-24和PKUAC-GDTS1-29中的含量分别为157.29 mg/g DW和374.86 mg/g DW，类胡萝卜素分别为65.13 mg/g DW和18.87 mg/g DW。【结论】基于系统发育树研究，本实验的2个分离株属于细鞘丝藻亚科(Leptolyngbyaceae)，与研究较少的纤发鞘丝蓝细菌属(Leptolyngbya)菌株相近，可能是广东和四川温泉中存在的一种新型丝状轻度嗜热蓝细菌属或Leptolyngbya新种。嗜热菌株PKUAC-GDTS1-24和PKUAC-GDTS1-29的形态和细胞组成相似，通过比较，2个菌株的藻胆蛋白含量远远高于其他研究报道的Leptolyngbya蓝细菌，尤其是PKUAC-GDTS1-29可以作为藻蓝蛋白生产的潜在菌株。

Abstract:

[Background] With the increase of CO2 emissions and global temperatures, thermophilic cyanobacteria are considered as a promising group of organisms to convert CO2 into useful chemicals and biofuels at 45 °C or above. [Objective] This paper describes isolation and identification of thermophilic cyanobacteria collected from Huizhou area, and describes growth characteristics of two strains belonging to the family Leptolyngbyaceae to provide the basis for their subsequent application. [Methods] 16S rRNA gene and phycocyanin alpha chain (PhycoA) gene sequences were used in phylogenetic analysis to determine the taxonomical position of isolates from Huizhou area. Two strains PKUAC-GDTS1-24 and PKUAC-GDTS1-29 were observed morphologically and analyzed for major cellular components (ash, carbohydrate, lipid, protein and pigment). [Results] Twelve strains of thermophilic cyanobacteria were isolated, of which PKUAC-GDTS1-24 and PKUAC-GDTS1-29 were morphologically blue-green globular trichomes. Cells forming trichome formed dense clusters, that mostly attached to each other. Cellular contents of: ash, lipids, and protein were estimated to be 24.41%, 21.40%, 26.64%, respectively in PKUAC-GDTS1-24 strain. Carbohydrates were the major component of the strain at 36.42%. In another strain, PKUAC-GDTS1-29, the cellular contents of: ash, lipids, and protein contents were estimated to be 24.72%, 23.92%, 12.93%, respectively. The carbohydrates once again were the most abundant component with 28.46%. The contents of phycocyanin (PC) in PKUAC-GDTS1-24 and PKUAC-GDTS1-29 were 157.29 and 374.86 mg/g dry weight respectively, and the carotenoids were 65.13 and 18.87 mg/g dry weight, respectively. [Conclusion] Based on the phylogeny, PKUAC-GDTS1-24 and PKUAC-GDTS1-29 belong to the family Leptolyngbyaceae and cluster with many poorly described isolates. These isolates may be a potentially novel phylotype or a new genus of filamentous mildly thermophilic cyanobacteria that are present in the hot springs of Guangdong and Sichuan. The morphological features and cellular composition of both thermophilic Leptolynbya-like strains were similar. To our best knowledge, the two strains are the highest phycobiliprotein producers described to date from this cyanobacterial family, which could be used as potential strains for phycocyanin production, especially PKUAC-GDTS1-29.