Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Hyderabad, India.
Bacterial Discovery Laboratory, Centre for Environment, Institute of Science and Technology, J.N.T. University Hyderabad, Hyderabad, India.
Sci Rep. 2021 Apr 30;11(1):9394. doi: 10.1038/s41598-021-88658-x.
Our major concern was to address "yeast endobacteria" which was based on a few reports in the recent past where bacteria may find yeast as a niche for survival. In this study, we report the microbiota of twenty-nine axenic yeast cultures recovered from different habitats based on their 16S rRNA gene-amplicon metagenomes. Yeasts were identified based on D1/D2 or ITS gene sequences. Bacterial diversity was widespread, varied and rich among all yeasts except for four strains. Taxa belonging to the phylum Firmicutes, Proteobacteria, Actinobacteria and Bacteroidetes and the genera; Streptococcus, Propionibacterium were common to all the yeasts. Candida tropicalis was used as a model organism to confirm bacteria through fluorescence in situ hybridization (FISH), isolating and re-introducing the isolated bacteria into the yeast. FISH analysis confirmed the endobacteria of C. tropicalis and we have successfully isolated four bacteria only after lysis and disruption of yeast cells. These bacteria were identified as species of Pseudomonas, Chryseobacterium, Lysinibacillus and Propionibacterium. Guestimates indicate 95% of bacterial species of C. tropicalis are yet-to-be-cultivated. We have successfully reintroduced mCherry tagged Pseudomonas into C. tropicalis. Also, auto-fluorescent Prochlorococcus and Rhodopseudomonas could be introduced into C. tropicalis while mCherry tagged E. coli or Salmonella could not be introduced. FISH analysis confirmed the presence of both native and infected bacterial cells present in C. tropicalis. Our findings unveil the insights into the ghost microbiota associated with yeast, which otherwise are considered to be axenic cultures. Their inherent occurrence, together with co-cultivation experiments under laboratory conditions suggests that yeasts are a thriving hub for bacterial communities.
我们主要关注的是“酵母内生菌”，这是基于过去几年的一些报告，其中细菌可能会发现酵母是生存的小生境。在这项研究中，我们报告了从不同栖息地回收的 29 个无菌酵母培养物的微生物组，基于其 16S rRNA 基因扩增子宏基因组。酵母是根据 D1/D2 或 ITS 基因序列鉴定的。除了四个菌株外，所有酵母中的细菌多样性广泛、多样且丰富。属于厚壁菌门、变形菌门、放线菌门和拟杆菌门以及链球菌属、丙酸杆菌属的分类群在所有酵母中都很常见。热带假丝酵母被用作模型生物，通过荧光原位杂交（FISH）确认细菌，分离并将分离的细菌重新引入酵母中。FISH 分析证实了热带假丝酵母的内生菌，并且我们仅在裂解和破坏酵母细胞后成功分离出四种细菌。这些细菌被鉴定为假单胞菌、黄杆菌、溶杆菌和丙酸杆菌的物种。估计表明，热带假丝酵母 95%的细菌物种尚未被培养。我们已经成功地将 mCherry 标记的假单胞菌重新引入热带假丝酵母中。此外，可以将自荧光原绿球藻和红假单胞菌引入热带假丝酵母中，而 mCherry 标记的大肠杆菌或沙门氏菌则不能引入。FISH 分析证实了存在于热带假丝酵母中的天然和感染的细菌细胞。我们的发现揭示了与酵母相关的幽灵微生物组的见解，否则这些酵母被认为是无菌培养物。它们的固有存在，以及在实验室条件下的共培养实验表明，酵母是细菌群落的繁荣中心。
