Microorganisms contain a large number of biocatalysts, which are of great potential in industrial applications. However, the traditional cultural approaches can obtain only less than 1% of microorganisms. As a culture-independent method, metagenomics is an advanced solution by means of extracting all microbial genomic DNAs in certain environmental habitat, constructing and screening metagenomic libraries to seek novel functional genes. It serves as an effective tool for studying these uncultured microorganisms. Therefore, mining novel biocatalysts from metagenome has drawn the attention of researchers in the world. In this paper, environment sample category, genomic DNA extraction, library construction and screening strategies were reviewed. Recent examples of isolated biocatalysts from metagenomic libraries were presented. Future research directions of metagenomics were also discussed.
Biocatalysis ; DNA ; Genomic Library ; Metagenomics ; trends

With the widely application of the metagenomics, the relationship between microbiota and disease has become a hot research topic. Understanding the potential association between upper gastrointestinal cancer or precancerous lesions and microbiota may play an important role in the early detection, clinical diagnosis and treatment, and prognostic evaluation of upper gastrointestinal cancer. Therefore, a literature retrieval was conducted by using PubMed, Embase and wanfang databases to summarize the latest research progress in the microbiota of upper gastrointestinal cancer, including oral, esophageal, gastric cancer and precancerous lesions. Lower microbial diversity or richness in esophageal cancer and precancerous lesions and specific prognostic biomarkers for esophageal cancer were found. Lactobacillus richness showed an increase trend during the process from gastritis to gastric cancer. This paper summarizes the progress in the research of potential biological etiology of upper gastrointestinal cancer from the perspective of metagenomics in order to provide evidence on the, prevention and control of upper gastrointestinal cancer.
Esophageal Neoplasms/microbiology* ; Gastrointestinal Microbiome ; Gastrointestinal Neoplasms/microbiology* ; Gastrointestinal Tract/microbiology* ; Humans ; Lactobacillus ; Metagenomics/trends* ; Microbiota ; Precancerous Conditions/microbiology* ; Prognosis ; Research/trends* ; Risk Factors ; Stomach Neoplasms/microbiology*