Engineering CrtW and CrtZ for improving biosynthesis of astaxanthin in Escherichia coli.

This study engineered β-carotene ketolase CrtW and β-carotene hydroxylase CrtZ to improve biosynthesis of astaxanthin in Escherichia coli. Firstly, crtW was randomly mutated to increase CrtW activities on conversion from β-carotene to astaxanthin. A crtW* mutant with A6T, T105A and L239M mutations has improved 5.

Diversity of Salmonella isolates using serotyping and multilocus sequence typing.

One hundred and twenty-one Salmonella isolates were obtained from food, feed, and live chicken samples derived from 13 countries or regions. In this study, their subtypes were evaluated by serotyping and multilocus sequence typing (MLST), and their genetic profiles were also characterized. It was demonstrated by serotyping on these isolates that 36 various serovars were obtained in this study, of which three serotypes S.

Development of a quantitative polymerase chain reaction method using a live bacterium as internal control for the detection of Listeria monocytogenes.

A novel real-time quantitative polymerase chain reaction (Q-PCR) assay was developed for rapid and accurate detection of Listeria monocytogenes. In this Q-PCR assay, a computational DNA random shuffling method was used to design an internal amplification control (IAC) sequence, which was the same in length and G + C content to the hly amplicon. This IAC sequence was inserted into the genome of L.