杜氏盐藻促生菌株的分离与鉴定

拟通过探究藻际微生物对微藻生长及代谢产物积累的影响,筛选出促进微藻生长的促生菌株。以杜氏盐藻(Dunaliella salina)Ds-SXYC-2为试材,分离鉴定盐藻藻际环境中的共生菌株,进一步构建藻菌(1∶1)共培养体系、测试盐藻生长及代谢产物积累等表型。结果显示,从杜氏盐藻藻际环境分离获得5株共生菌株,经16S rDNA分子鉴定,属于3个菌属。菌株B1与B2为涅斯捷连科氏菌(Nesterenkonia),菌株B3与B4为盐单胞菌(Halomonas),菌株B5为海杆菌(Marinobacter)。5株共生菌株对杜氏盐藻的生长均有促进作用,菌株B3能显著促进杜氏盐藻生长及代谢产物的积累。共培养15 d后,杜氏盐藻生物量达到2.3 g/L,比对照组增加了28.9%,叶绿素a的含量达到4.61 mg/L,比对照组增加了36.3%,β-胡萝卜素比对照组提高了56.4%。盐藻多糖、蛋白质、总脂含量分别比对照组增加了34.8%、71.2%和37.6%。菌株B3盐单胞菌可以作为促进杜氏盐藻生长及代谢产物累积的优势菌株,进一步构建共培养体系可应用于杜氏盐藻的商业生产。

Isolation and Identification of the Growth-promoting Bacteria from Pbycosphere of Dunaliella salina

Through exploring the influence of phycosphere microorganisms on the microalgae growth and metabolite accumulation,the predominant growth-promoting strains were screened.The symbiotic bacterial strains from the phycosphere of Dunaliella salina Ds-SXYC-2 were isolated and identified,and 1∶1 algal-bacteria co-culture system was constructed,and the growth of D.salina and the accumulation of its metabolite were measured.The results showed that 5 symbiotic bacterial strains were isolated from the phycosphere of D.salina,and they belonged to 3 genera,including Nesterenkonia(Strain B1 and B2),Halomonas(strain B3 and B4),and Marinobacter(Strain B5).All the 5 strains promoted the growth of D.salina.Among them,strain B3 significantly promoted the growth and the accumulation of metabolites.After 15 d of co-culture,the biomass of D.salina reached 2.3 g/L,which was higher than that of the control without bacteria and increased by 28.9%.The content of chlorophyll a(4.61 mg/L)and beta-carotene increased by 36.3% and 56.4%,respectively,in contrast to the control.The contents of intracellular polysaccharide,proteins and total lipids increased by 34.8%,71.2% and 37.6%,respectively,compared with the control group.Halomonas strain B3 could be used as the dominant strain to promote the growth and metabolite accumulation of D.salina,and the co-culture system could be constructed and applied to the commercial production of D.salina.