Progress in the construction and screening of random mutation library / 生物工程学报

Directed evolution is a cyclic process that alternates between constructing different genes and screening functional gene variants. It has been widely used in optimization and analysis of DNA sequence, gene function and protein structure. It includes random gene libraries construction, gene expression in suitable hosts and mutant libraries screening. The key to construct gene library is the storage capacity and mutation diversity, to screen is high sensitivity and high throughput. This review discusses the latest advances in directed evolution. These new technologies greatly accelerate and simplify the traditional directional evolution process and promote the development of directed evolution.

Biocontrol potential of saline- or alkaline-tolerant Trichoderma asperellum mutants against three pathogenic fungi under saline or alkaline stress conditions

ABSTRACT Salinity and alkalinity are major abiotic stresses that limit growth and development of poplar. We investigated biocontrol potential of saline- and alkaline-tolerant mutants of Trichoderma asperellum to mediate the effects of salinity or alkalinity stresses on Populus davidiana × P. alba var. pyramidalis (PdPap poplar) seedlings. A T-DNA insertion mutant library of T. asperellum was constructed using an Agrobacterium tumefaciens mediated transformation system; this process yielded sixty five positive transformants (T1T65). The salinity tolerant mutant, T59, grew in Potato Dextrose Agar (PDA) containing up to 10% (1709.40 mM) NaCl. Under NaCl-rich conditions, T59 was most effective in inhibiting Alternaria alternata (52.00%). The alkalinity tolerant mutants, T3 and T5, grew in PDA containing up to 0.4% (47.62 mM) NaHCO3. The ability of the T3 and T5 mutants to inhibit Fusarium oxysporum declined as NaHCO3 concentrations increased. NaHCO3 tolerance of the PdPap seedlings improved following treatment with the spores of the WT, T3, and T5 strains. The salinity tolerant mutant (T59) and two alkalinity tolerant mutants (T3 and T5) generated in this study can be applied to decrease the incidence of pathogenic fungi infection under saline or alkaline stress.

Biocontrol potential of saline- or alkaline-tolerant Trichoderma asperellum mutants against three pathogenic fungi under saline or alkaline stress conditions

ABSTRACT Salinity and alkalinity are major abiotic stresses that limit growth and development of poplar. We investigated biocontrol potential of saline- and alkaline-tolerant mutants of Trichoderma asperellum to mediate the effects of salinity or alkalinity stresses on Populus davidiana × P. alba var. pyramidalis (PdPap poplar) seedlings. A T-DNA insertion mutant library of T. asperellum was constructed using an Agrobacterium tumefaciens mediated transformation system; this process yielded sixty five positive transformants (T1-T65). The salinity tolerant mutant, T59, grew in Potato Dextrose Agar (PDA) containing up to 10% (1709.40 mM) NaCl. Under NaCl-rich conditions, T59 was most effective in inhibiting Alternaria alternata (52.00%). The alkalinity tolerant mutants, T3 and T5, grew in PDA containing up to 0.4% (47.62 mM) NaHCO3. The ability of the T3 and T5 mutants to inhibit Fusarium oxysporum declined as NaHCO3 concentrations increased. NaHCO3 tolerance of the PdPap seedlings improved following treatment with the spores of the WT, T3, and T5 strains. The salinity tolerant mutant (T59) and two alkalinity tolerant mutants (T3 and T5) generated in this study can be applied to decrease the incidence of pathogenic fungi infection under saline or alkaline stress.

SCREENING OF STRAINS PRODUCING LIPASES WITH HIGH ACTIVITIES AND CONSTRUCTION OF STRAIN LIBRARY / 微生物学通报

More than 80 strains producing lipases were screened from oily soil of vegetable oil plant, meat processing factory and dairy factory in Jinan city, Shandong Province, which included bacteria, moulds and yeast. Conditions for lipase production and properties of some enzymes were studied. One drug-resistant mutant strain Y-11 with higher lipase activity was from Trichosporon sp. Y-1. In addition, Optimization of lipase production and characterization of enzymes were carried out. On the basis of above experiments, a characteristic library of stains producing lipases was established.