Recent Advances in Function-based Metagenomic Screening / 基因组蛋白质组与生物信息学报·英文版

Metagenomes from uncultured microorganisms are rich resources for novel enzyme genes. The methods used to screen the metagenomic libraries fall into two categories, which are based on sequence or function of the enzymes. The sequence-based approaches rely on the known sequences of the target gene families. In contrast, the function-based approaches do not involve the incorporation of metagenomic sequencing data and, therefore, may lead to the discovery of novel gene sequences with desired functions. In this review, we discuss the function-based screening strategies that have been used in the identification of enzymes from metagenomes. Because of its simplicity, agar plate screening is most commonly used in the identification of novel enzymes with diverse functions. Other screening methods with higher sensitivity are also employed, such as microtiter plate screening. Furthermore, several ultra-high-throughput methods were developed to deal with large metagenomic libraries. Among these are the FACS-based screening, droplet-based screening, and the in vivo reporter-based screening methods. The application of these novel screening strategies has increased the chance for the discovery of novel enzyme genes.

Rapid screening of tannase producing microbes by using natural tannin

Use of natural tannin in the screening of tannase producing microbes is really promising. The present work describes about the possibility and integrity of the newly formulated method over the previously reported methods. Tannin isolated from Terminalia belerica Roxb. (Bahera) was used to differentiate between tanninolytic and nontanninolytic microbes. The method is simple, sensitive and superior for the rapid screening and isolation of tannase-producing microbes.

A NOVEL STRATEGY FOR SCREENING MUTANT ENZYMES UNDER NON-GROWTH CONDITIONS / 微生物学通报

The technique of double-layered plate was developed for screening the library of mutant endoglucanase III from Trichoderma reesei generated by the method of directed evolution.The enzyme activity was determined according to the velocity of the formation of halos on the plates.Several mutants with higher activity than the wild type at low temperature or alkaline pH were obtained by using this strategy under different screening conditions.Further results of spectrophotometric determination of the activities of these mutants were consistent with the results of plate screening.The establishment of such strategy will broaden the applications of the directed evolution methods for improving the existing proteins to obtain useful enzymes with new properties for industrial applications.