The consumption of lactate and amino acids is very important for microbial development and/or aroma production during cheese ripening. A strain of Yarrowia lipolytica isolated from cheese was grown in a liquid medium containing lactate in the presence of a low (0.1x) or high (2x) concentration of amino acids. Our results show that there was a dramatic increase in the growth of Y. lipolytica in the medium containing a high amino acid concentration, but there was limited lactate consumption. Conversely, lactate was efficiently consumed in the medium containing a low concentration of amino acids after amino acid depletion was complete. These data suggest that the amino acids are used by Y. lipolytica as a main energy source, whereas lactate is consumed following amino acid depletion. Amino acid degradation was accompanied by ammonia production corresponding to a dramatic increase in the pH. The effect of adding amino acids to a Y. lipolytica culture grown on lactate was also investigated. Real-time quantitative PCR analyses were performed with specific primers for five genes involved in amino acid transport and catabolism, including an amino acid transporter gene (GAP1) and four aminotransferase genes (ARO8, ARO9, BAT1, and BAT2). The expression of three genes involved in lactate transport and catabolism was also studied. These genes included a lactate transporter gene (JEN1) and two lactate dehydrogenase genes (CYB2-1 and CYB2-2). Our data showed that GAP1, BAT2, BAT1, and ARO8 were maximally expressed after 15 to 30 min following addition of amino acids (BAT2 was the most highly expressed gene), while the maximum expression of JEN1, CYB2-1, and CYB2-2 was delayed (60 min).
- American Society for Microbiology
- Lactate and amino acid catabolism in the cheese-ripening yeast ...
Use of bauxite for enhanced removal of bacteria in slow sand filters
Slow sand filtration (SSF) is a well-known process for drinking water treatment and is widely used for the production of biologically stable drinking water and particle removal. The removal process of particles and microorganisms is highly dependent on the buildup of the schmutzdecke at the filter surface. During the ripening period and especially for cold waters, the buildup of the schmutzdecke may take several months until such filters are biologically mature and at steady-state regarding their removal performanc...
Identification of the bacterial population in manganese removal filters
The aim of this study was to identify bacteria present in ripened manganese removal filters for drinking water production. The bacterial population was identified with ‘next generation’ DNA sequencing, and specific bacteria were quantified with quantitative polymerase chain reaction (qPCR) and characterized by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) analysis. The ‘next generation’ DNA sequencing analysis showed a bacteria population shift from the iron oxidizing...
Onion Slices Drying Processes
The dehydrated vegetable is a kind of food with popularity to meet the fast-paced and high-efficiency life style of nowadays. After drying, the moisture content of vegetables are reduced to 4%-13%, and the water activity (Aw) is reduced to around 0.7, which makes the microorganism and enzyme in an inhibition state, thus the dried vegetable can be preserved for 2-3 years after sealed or vacuum packed. So dehydration and drying is a common process of vegetables. With the increased utilization of dehydrated onions,...
Bi-On reduces the incidence of oleocellosis in Navel oranges
Citrus fruit exhibit low levels of ethylene production and are classified as non-climacteric fruit. Although the citrus fruits produce only small amounts of ethylene it is well known that the fruit do respond to ethylene. Such as non-climacteric fruits, ethylene exposure does not hasten fruit ripening but accelerates fruit senescence.Certain unwanted responses of citrus fruit to ethylene in storage are the enhancement of chilling injury symptoms, decay and stem end rots. Published studies indicate that the use of...
Case study - Le Verger de la Blottière
Le Verger de la Blottière is a family-run company located in Maine-et-Loire in western France, which has been producing highly valued and quality apples and pears for three generations.Le Verger de la Blottière produces 20 different varieties of apples and pears, all valued for their taste and aromatic properties, where the notable Antares apple merits mention, which was created in house and has exclusive commercialisation.In 2004, the company cofounded the Demain la Terre Association. This associatio...