ABSTRACT
Mold species that grew on the surface of retailed strawberries (10 packs, 211 strawberries) and cherries (18 packs, 441 cherries) during storage at 25 degrees C were isolated and identified to evaluate the state of mold growth. Mold growth was observed on 208 (98.6%) of the 211 strawberries and 193 (43.8%) of the 441 cherries. The mold species most frequently isolated from strawberries was Botrytis cinerea, being observed in 81.0% of the strawberries examined, followed by Cladosporium and Alternaria alternata. The mold most frequently isolated from cherries was Alternaria (28.7%), followed by Penicillium, Botrytis, and Cladosporium. The frequency of cherries on which mold growth was observed varied among packs. Mold tended to grow more often in the areas of the fruits in contact with adjacent fruits.
Subject(s)
Food Contamination , Food Handling , Food Microbiology , Fragaria/microbiology , Fungi/isolation & purification , Prunus/microbiology , Temperature , Alternaria/growth & development , Alternaria/isolation & purification , Botrytis/growth & development , Botrytis/isolation & purification , Cladosporium/growth & development , Cladosporium/isolation & purification , Fungi/growth & development , Penicillium/growth & development , Penicillium/isolation & purificationABSTRACT
An attempt was made to express protease BYA produced by an alkalophilic Bacillus sp. Y in Bacillus subtilis by gene engineering methods. The gene encoding protease BYA was cloned from Bacillus sp. Y, and expression vector pTA71 was constructed from the amylase promoter of Bacillus licheniformis, DNA fragments encoding the open reading frame of protease BYA, and pUB110. Protease BYA was secreted at an activity level of 5100 APU/ml in the common industrial culture medium of Bacillus subtilis transformed with pTA71. We then attempted to increase the specific activity of protease BYA by site-directed mutagenesis. Amino acid residue Ala29 next to catalytic Asp30 was replaced by one of three uncharged amino acid residues (Val29, Leu29, Ile29), and each mutant enzyme was expressed and isolated from the culture medium. Val29 mutant enzyme was secreted at an activity level of greater than 7000 APU/ml in culture medium, and its specific activity was 1.5-fold higher than that of the wild-type enzyme. Other mutant enzymes had specific activity similar to that of the original one and were less stabile than the wild-type enzyme. It can be thought that the substitution at amino acid residue 29 affects the level of activity and stability of protease BYA.
Subject(s)
Bacillus subtilis/enzymology , Bacillus subtilis/genetics , Bacillus/enzymology , Amylases/biosynthesis , Amylases/genetics , Bacillus/genetics , Base Sequence , Cloning, Molecular , DNA Primers , DNA Probes , DNA, Bacterial/biosynthesis , DNA, Bacterial/genetics , Genetic Vectors , Molecular Sequence Data , Mutagenesis, Site-Directed , Plasmids/genetics , Promoter Regions, Genetic/geneticsABSTRACT
Between September 2000 and March 2003 healthy subjects in 10 prefectures of Japan were investigated to identify carriers of Neisseria meningitidis. Twenty-five N. meningitidis strains were isolated from 5886 throat swab specimens collected from healthy persons, such as students, elderly, and foreigners. Of the 25 carriers, 9 were teenagers, 15 were in their twenties, and only one was in the fifties. The male-female ratio of the carriers was 17 to 8, showing male dominance. The serogroups of the 25 strains were B (9 strains), Y (4 strains) and non-groupable (12 strains). One of the strains was found to be deficient in gamma-glutamyl aminopeptidase activity, which is an identification marker for N. meningitidis.