Analysis of microbiota of the swimming crab (Portunus trituberculatus) in South Korea to identify risk markers for foodborne illness

Differences in diversity and community composition of the shell microbiome of apparently healthy lobsters Homarus americanus across Atlantic Canada

Host-microbe dynamics are of increasing interest in marine research due to their role in host health and productivity. Changes in the shell microbiome of American lobsters have been associated with epizootic shell disease, a syndrome that is spreading northwards across the eastern U.S. and Canadian Atlantic coast. This study analyzed differences in alpha and beta diversity, as well as differentially abundant taxa, in the shell-associated bacterial community of apparently healthy lobsters from four lobster fishing areas (LFAs) in Atlantic Canada. Over 180 lobsters from New Brunswick, Nova Scotia and Prince Edward Island (PEI) were sampled during seven sampling events over four sampling months. The bacterial community was identified using novel PacBio long-read sequencing, while alpha and beta diversity parameters were analyzed using linear regression models and weighted UniFrac distances. The bacterial richness, diversity and evenness differed by sampling location, sampling month, and molt stage, but not by lobster sex or size, nor sampling depth. Similarly, based on LFA, sampling month, year and lobster molt stage, the shell microbiome differed in microbial community composition with up to 34 out of 162 taxa differing significantly in abundance between sampling groups. This large-scale microbial survey suggests that the shell microbial diversity of apparently healthy lobsters is influenced by spatial and temporal factors such as geographic location, as well as the length of time the carapace is exposed to the surrounding seawater.

Comparison of 16S rRNA Gene Based Microbial Profiling Using Five Next-Generation Sequencers and Various Primers

Microbial community analysis based on the 16S rRNA-gene is used to investigate both beneficial and harmful microorganisms in various fields and environments. Recently, the next-generation sequencing (NGS) technology has enabled rapid and accurate microbial community analysis. Despite these advantages of NGS based metagenomics study, sample transport, storage conditions, amplification, library preparation kits, sequencing, and bioinformatics procedures can bias microbial community analysis results. In this study, eight mock communities were pooled from genomic DNA of Lactobacillus acidophilus KCTC 3164^T, Limosilactobacillus fermentum KCTC 3112^T, Lactobacillus gasseri KCTC 3163^T, Lacticaseibacillus paracasei subsp. paracasei KCTC 3510^T, Limosilactobacillus reuteri KCTC 3594^T, Lactococcus lactis subsp. lactis KCTC 3769^T, Bifidobacterium animalis subsp. lactis KCTC 5854^T, and Bifidobacterium breve KCTC 3220^T. The genomic DNAs were quantified by droplet digital PCR (ddPCR) and were mixed as mock communities. The mock communities were amplified with various 16S rRNA gene universal primer pairs and sequenced by MiSeq, IonTorrent, MGIseq-2000, Sequel II, and MinION NGS platforms. In a comparison of primer-dependent bias, the microbial profiles of V1-V2 and V3 regions were similar to the original ratio of the mock communities, while the microbial profiles of the V1-V3 region were relatively biased. In a comparison of platform-dependent bias, the sequence read from short-read platforms (MiSeq, IonTorrent, and MGIseq-2000) showed lower bias than that of long-read platforms (Sequel II and MinION). Meanwhile, the sequences read from Sequel II and MinION platforms were relatively biased in some mock communities. In the data of all NGS platforms and regions, L. acidophilus was greatly underrepresented while Lactococcus lactis subsp. lactis was generally overrepresented. In all samples of this study, the bias index (BI) was calculated and PCA was performed for comparison. The samples with biased relative abundance showed high BI values and were separated in the PCA results. In particular, analysis of regions rich in AT and GC poses problems for genome assembly, which can lead to sequencing bias. According to this comparative analysis, the development of reference material (RM) material has been proposed to calibrate the bias in microbiome analysis.

Characterization of fungus microbial diversity in healthy and diarrheal yaks in Gannan region of Tibet Autonomous Prefecture

Diarrhea is a serious epidemic in yaks on Qinghai Tibet plateau, but the exact pathogen is not confirmed. Diarrhea is related to the changes in diversity of intestinal flora. The current study herein is performed for high-throughput sequencing of fungus microbial diversity in healthy adult yaks, diarrheal adult yaks and diarrheal yak calves in Gannan Tibetan Autonomous Prefecture. A total 446726 optimized sequences were achieved. Over 250 OTUs in species level have been indentified for each sample. The Shannon and Simpson index revealed that there was no visible difference in the flora between different yak groups (p > 0.05). However, obvious difference was watched in the principal component of microbial community structure in different yak groups by PCA analysis, especially between healthy adult yak group and diarrheal adult yak groups. There were 248 fungus species shared in three groups. Interestingly, there were 97 fungus species shared in the diarrheal groups (calves and adult yaks), which were not found in the healthy yaks, while there were 212 fungus species only found in the healthy yaks. In the Phylum level, 1 phylum (Neocallimastigomycota) was discovered to have significant difference between healthy yaks and diarrheal yak calves (p < 0.05). In the genus level, 23 genus were found obvious difference between healthy adult yaks and diarrheal adults yaks (p < 0.05); 28 genus were found significant difference between healthy adult yaks and diarrheal yak calves (p < 0.05); 23 genus were found obvious difference between diarrheal adult yaks and diarrheal yak calves (p < 0.05). The present study herein first reported an insight of the change of microbial diversity of fungus in diarrhea yaks at altitude regions, which contributed towards the solid prevention of diarrhea in yaks.