Project description:L. helveticus is used to modulate cheese flavor and as a starter organism in certain cheese varieties. Our group has compiled a draft (4x) sequence for the 2.4 Mb genome of an industrial strain L. helveticus CNRZ32. The primary aim was to investigate expression of 168 completely sequenced genes during growth in milk and MRS medium using microarrays. Oligonucleotide probes against each of the completely sequenced genes were compiled on maskless photolithography-based DNA microarrays. Additionally, the entire draft genome sequence was used to produce tiled microarrays where the non-interrupted sequence contigs were covered by consecutive 24-mer probes. Keywords: growth conditions response
Project description:The enzymatic repertoire of starter cultures is important for cheese characteristics but is challenging to characterize due to the high protein and fat concentration, and the semi-solid state of the cheese matrix. This study aimed to generate a protocol to characterize the proteome of bacteria harvested from milk and cheese, to assess the proteome differences between Lactococcus cremoris grown in milk and laboratory medium, and to investigate the proteome adaptation during cheese production and ripening.
Project description:Growth of L. cremoris NCDO712 was not altered when manganese is omitted from its defined medium. This study was conducted in order to compare protein requirements of Lactococcus cremoris NCDO712 to grow in the presence or absence of manganese in defined medium (1% lactose). The majority of protein adaptation involves upregulation of Mn transporters and to a lesser extent various NADH-dependent proteins. Such adaptation is highly relevant for starter culture in dairy fermentation where manganese is limited and NADH homeostasis determines the formation of volatiles during long-term incubation e.g. cheese ripening.
Project description:This project characterizes the temporal dynamics of microbial communities and functional potential in strong-flavor Daqu (a traditional Chinese fermentation starter) across a 4-month storage period.
Project description:To study the characteristics of proteins in Chinese Chixiang-flavor Baijiu fermentation, a label-free quantitative proteomics approach was established to identify proteins in Jiuqu starter and fermented grains.
Project description:Propionibacterium freudenreichii is used as a ripening culture in Swiss cheese manufacture. It produces flavor compounds over the whole ripening period. During cheese ripening, P. freudenreichii is exposed to a temperature downshift, especially when cheeses are transferred from warm temperature (about 24°C) to cold temperature (about 4°C). The cold adaptation of the type strain was studied previously. The aim of this study was to investigate the adaptation of 6 other P. freudenreichii strains at cold temperature by means of a global gene expression profile. The temporal transcriptomic response of 6 P. freudenreichii strains was analyzed at 2 times of growth, during growth at 30°C then after 3 days 4°C, in the constant presence of lactate as the main carbon source.
