Characterization of disease-associated microbiota in hepatocellular carcinoma.

Aims: This study aimed to investigate the differences in the composition of microbial communities and related functions in hepatocellular carcinoma (HCC) tumours and matched normal tissues were investigated.

Methods and material: Tumour tissues and matched normal samples were collected from 30 HCC patients. Genomic DNA was collected and subjected to sequencing of the V3 + V4 region of the 16S rRNA gene. The microbial community profiles and metabolic pathway predictions of the different groups were characterized and compared.

Results: Tumour and adjacent tissues had similar microbiota compositions but differed in abundance. Proteobacteria and Firmicutes abundance decreased and Cyanobacteria and Acidobacteria abundance increased in the tumour tissue. The microbial community diversity was higher in the tumour tissues than in adjacent samples, with potentially more dominant taxa in the adjacent tissues, including Firmicutes, Proteobacteria, and Actinobacteria. Acidobacteria, Cyanobacteria, and Chloroflexi were the dominant microbes in tumour tissues. A total of 46 metabolic pathways were identified. Global and overview maps were the most abundant pathways, followed by carbohydrate metabolism, energy metabolism, metabolism of cofactors and vitamins, and membrane transport. The top 50 most highly correlated microbial genera included Klebsiella, Rhodococcus, Ochrobactrum, and Azoarcus. Fonticella, Haloimpatiens, Brevibacterium, and Acidothermus were positively correlated with other microbial genera. The microbiota of adjacent tissues was more robust in the network analysis.

Conclusions: This study revealed differences in microbial composition between HCC tumour tissues and normal tissues and differences in microbial abundance associated with different metabolic functions. Cyanobacteria, Proteobacteria, and Actinobacteria may play important roles in HCC.