High-throughput sequencing analysis of intestinal flora diversity of two freshwater snails (Radix auricularia and Planorbella trivolvis) / 生物工程学报

Freshwater snail is an important biological group in aquatic ecosystem and an intermediate host of many parasites. Intestinal flora plays an important role in animal energy metabolism and resistance to pathogens. We analyzed the intestinal microbiota diversity of Radix auricularia (RA) and Planorbella trivolvis (PL) by 16S rRNA high-throughput sequencing. At the phylum level, RA had 23 phyla, including Proteobacteria (33.63%), Cyanobacteria (15.33%), Chloroflexi (13.95%), and Actinomycetes (12.99%). PL had 13 phyla, including Proteobacteria (54.88%), Bacteroidetes (28.49%), and Actinomycetes (7.65%). At the genus level, there were 445 genera in RA, including Pleurocapsa, Thiodictyon, Leptotrichia, and Nocardioides. There were 238 genera in PL, including Cloacibacterium, OM60NOR5_clade, Pseudomonas, and Rhodobacter. Ninety-three genera were the common core flora of the two snail species (all the samples were present), and 27 genera had an abundance greater than 0.5%. The structure of intestinal microbiota was significantly different between the two groups (P=0.027). We performed the functional prediction of intestinal microbiota using Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt), and the results show that the KEGG functional composition of the intestinal flora of the two snails was similar, and the abundance of the amino acid metabolism, carbohydrate metabolism and membrane transport were large. In summary, the intestinal microbiota of the two snails was high in diversity and significantly different, but there were a large number of common core flora.

The molecular diversity analysis of Auricularia auricula-judae in China by nuclear ribosomal DNA intergenic spacer

Background: For the crossbreeding of Auricularia auricula-judae, selecting the appropriated parents in hybridization is very important. However, the classification and diversity analysis of A. auricula-judae has been equivocal, due to the similarity of the fruiting body morphology and its susceptibility to environmental influences. For this purpose, the molecular diversity of 32 A. auricula-judae commercial cultivars in China was analyzed by using the nuclear ribosomal DNA intergenic spacer. Results: The complete nuclear rDNA gene complex of A. auricula-judae isolate is 11,210 bp long, and contains the 18S, 5.8S, and 28S rRNA gene as well as the ITS and IGS regions. Based on the sequence data, four more effective primer combinations for the IGS region of A. auricula-judae were designed. Nucleotide sequence variation in the IGS among 32 A. auricula-judae commercial cultivars in China sorted into three strongly supported clades, which is correlated with geographical regions. Most strains originated from the same area were with a narrow genetic basis and could possibly be domesticated from the local wild-type strains. Conclusion: The grouping information obtained in the present work provides significant information for further genetic improvement in A. auricula-judae, and suggested that the IGS region can be used as an excellent tool for identification of genetic variation.