Progress in Applied Microbiology

Lipase is an important and intensely studied biocatalyst. The structure and properties of microbial lipase and
its application in grain and oil food processing, biodiesel, organic synthesis, synthesis of chiral compounds and
determination of triglyceride structure were reviewed and discussed.

The biological treatment of sewage is the strengthening of water self-purifi cation. After removing the pollutants in the
sewage, the microorganisms must be separated from the water. This separation is mainly through the fl occulation of
microorganisms and the ingestion of protozoa and rotifers completed. This paper mainly introduces the application of
microorganisms in sewage treatment, and several major sewage biological treatment technologies.

Natamycin is a broad-spectrum antifungal agent produced by fermentation of strains such as Streptomyces natalensis,
Streptomyces gilvosporeus, Streptomyces chattanoogensis and other strains. Because of its low toxicity and minimal
change in the taste of the food itself can be used as a biological preservative. In this study, the strain of natamycin
was increased by adding fungal fermentation broth to Streptomyces nalus N5 strain. The results showed that the
fermentation broth of Penicillium chrysogenum, Aspergillus niger and Saccharomyces cerevisiae had a signifi cant
eff ect on the production of natamycin in Streptomyces natalus N5 strain. The results showed that the fermentation
broth Penicillium chrysogenum and Aspergillus niger had the best effect on the synthesis of N5 strain natamycin,
while that of Saccharomyces cerevisiae was the best on day 3, and the yield of natamycin was about 1 times higher
than fungi fermentation broth treated samples.

L-tryptophan is one of the eight amino acids necessary for human and animal life activities. It cannot be naturally
synthesized in the human body and must be taken from food. It exists in the living body in a free state or in a living
state. It plays a very important role in the physiological activities of animal growth, metabolism and so on. It is called
the second essential amino acid and is widely used in food, feed and medical industry. L-tryptophan production
methods are chemical synthesis, conversion and microbial fermentation. In recent years, with the successful use of
metabolic engineering in the breeding of tryptophan bacteria, microbial fermentation has gradually become the main
method of production of tryptophan. The metabolic engineering strategies involved in the production of tryptophan by
microbial fermentation were reviewed, including the mechanism of metabolic regulation of biotinylated tryptophan
and the measures and eff ects of pathway modifi cation. In addition, the future development of L-tryptophan was also
discussed.

In recent years, the extensive use of organophosphorus pesticides, especially the unreasonable use, has brought great
safety risks to the environment. Organic phosphorus pollution has become a hotspot, and there are a large number of
microorganisms in the soil and water body that can degrade organophosphorus pesticides. The extensive degradation
performance of pesticides is applied to a variety of pollution remediation practices. This paper summarizes the
current situation of organophosphorus pesticide use and pesticide residues, the species of organophosphorus pesticide
degrading bacteria and its separation and screening and degradation of pesticide characteristics of the research
progress.