Background：It is controversial whether colorectal cancer (CRC) impacts intestinal microbial alpha (α) diversity, and although some studies have suggested an association between intestinal microbiota and cancer risk, few have been used as a marker for CRC diagnosis. Methods：By searching PubMed and BioProject databases, we reanalysed published raw 16S ribosomal RNA (rRNA) gene sequences and metadata. We calculated α-diversity indices, screened the differentially enriched genera and species shared among different studies, identified potential CRC markers, and finally assessed the overall trend of these indices. Results：The pooled analysis showed that based on the fixed-effects model, α-diversity of the cancer group was lower than that of the non-cancer group, and there was significant heterogeneity. Heterogeneity was significantly reduced or eliminated when grouped by geographic region, study scope, and sequencing platform. We also found an association between gut microbiota and CRC. The genera Fusobacterium, Parvimonas, Gemella Campylobacter, and Peptostreptococcus were only enriched in the cancer group, while Faecalibacterium, Subdoligranulum, and Fusicatenibacter were dominant in the non-cancer group. At the same time, we also provide some evidence that Fusobacterium, Gemella, Faecalibacterium, and Subdoligranulum have diagnostic value in several studies and may be potential diagnostic markers of CRC. Conclusions： This analysis indicates an association between CRC and microbiota composition, and microbial markers could be used as diagnostic indicators of CRC. However, future studies should include more cohorts and wide sample sizes to identify the role of the different microbiota in CRC.

A male passenger arriving at Nanning Wuxu Airport in Guangxi on an international flight from Jakarta, Indonesia, was found to be positive for SARS-CoV-2 nucleic acid on a routine test at the airport on June 8 2021. The passenger was sent to Fourth People’s Hospital of Nanning immediately for further isolation and observation. On the day of admission, the test for SARS-CoV-2 nucleic acid of nasopharyngeal swabs, pharyngeal swabs and sputum specimens were positive (CT values of N gene and ORF1ab gene were between 20 and 30). After 8 weeks of hospitalization, the patient’s test for SARS-CoV-2 nucleic acid of all specimens turned to negative. We isolated a SARS-CoV-2 variant strain from the nasal swab of the patient, and then we found that the genome sequence of the variant strain had 13 base deletions and 38 nucleotide mutations compared with that of the Novel Coronavirus Wuhan strain after sequencing, comparison and analysis. The deletions and mutations of the variant strain resulted in four amino acid deletions and 30 amino acid mutations. Furthermore, we found that the variant strain was similar to those from Indonesia, South Korea and The United Kingdom after conducting BLAST analysis on GISAID platform, among them, hCOV-19 /Indonesia/ Ji-ITD-43591N /2021 was the most similar, with 99.98% similarity and only 8 base differences. The maximum likelihood phylogenetic tree was constructed taking the Wuhan strain as the root and including most the reference sequence contained most of the epidemic strains. The result showed that the strains isolated in our laboratory belonged to Delta strain.