ABSTRACT
In this study, plate transparent circle by Davis method was introduce firstly screening ?-Rhamnosidase high-yield strain. The spore-sprouted Aspergillus niger 8-hour were mutagenized by ethyl methane sulphonate and pre-screened via transparent circle. 11% mutants yield 40% higher of ?-rhamnosidase than the original strain. A high-yield strain, T-226 with the highest ?-rhamnosidase activity of 373.4 U/mL was finally selected from these potential high-yield mutants after rescreened by shake flask fermentation twice. When the T-226 strain was fermented in 5 L bioreactor, the enzyme activity could reach to 631.9 U/mL after 84 h. Thus, the established screening method is highly efficient to isolate ?-rhamnosidase high-yield mutant of A. niger.
ABSTRACT
In order to develop a rapid method which can check Campylobacter jejuni in animal and poultry foods nicely, an immunomagnetic capture-fluorescent PCR (IMC-FPCR) method was established in this paper. The reported method involves isolation of the target pathogen by immunocapture prior to the fluorescent PCR step, therefore the immunomagnetic-beads for Campylobacter were developed, and two groups of primer/probe, which targeted for the species special sequence of flaA gene and hipO gene for Campylobacter jejuni were designed. The immunomagnetic capture-fluorescent PCR assay amplification of the hipO gene and flaA gene for detection of Campylobacter jejuni was firstly reported in this paper. Result indicated that IMC-FPCR method permits direct detection of the pathogen without an enrichment step and can be performed in approximately 24 h. The assay results are positive for all of the isolates of Campylobacter jejuni (3 isolates, including type strain ATCC 33560 and ATCC8341) with a detection limit of approximately 10 cfu/mL, are negative for Campylobacter coli and several other bacteria. IMC-FPCR assay provide not only a rapid, sensitive method for quantitative detection of Campylobacter jejuni, but also an important method for detecting of Campylobacter jejuni of viable but non-culturerable (VNC) state.
Subject(s)
Campylobacter jejuni , Genetics , Fluorescence , Immunomagnetic Separation , Methods , Polymerase Chain Reaction , Methods , Sensitivity and SpecificityABSTRACT
This paper summarize the practice in the teaching reform of microbiology experiment in recent years. We identify the main contents of experimental teaching systems and pay much more attention to peo-ple-oriented. Through the reform of teaching and assessment methods,students are trained to cultivate their practical ability and spirit of innovation.