A unique sweetener
The work was carried out with Kluyveromyces lactis. The scientists have taught this type of fungus to produce two proteins that are important for the brazzein formation. This method allowed to obtain 2.6 times more brazzein than before. The taste of the protein was evaluated by volunteers. According to the volunteers, the resulted protein is more than 2000 times sweeter than sugar.
Danish scientists have developed a yogurt having a sweet taste without adding a sugar. They tried to solve the problem of abundance of added sugar in yogurt. And they have created an initially sweet yogurt, which, however, has more questions than answers. The scientists have altered metabolic characteristics of bacteria, helping to get the yogurt.
The idea was that the bacteria did not consume glucose – a sweet product of fermentation process of the yogurt. We must understand that the yogurt is a product that contains live cultures of Streptococcus thermophiles and some Lactobacillus delbrueckii. When these strains grow in milk, they usually decompose the lactose disaccharide into two monosaccharide - glucose and galactose.
Then they consume glucose and produce more galactose. But the scientists have made bacteria to consume galactose by spitting glucose. They have made this by growing the bacteria in a medium containing glucose analogue - 2-deoxyglucose, which is toxic for cells. So, in this way the scientists have got bacteria-mutants that are unable to process glucose.
Further mutants fell into a solution containing a high level of 2-deoxyglucose. As a result, the bacteria lost the glucose transport mechanism, completely. The final version of the bacteria produced a little bit of lactose and galactose, but the grate amount of glucose. It turned out that the yogurt, due to its high glucose content, became sweeter, but more harmful.