Tag: biotechnology and genetic engineering

When yeast is added to a mixture of dough, a fermentation process begins as the yeast eats the sugars and releases carbon dioxide gas. The yeast absorbs the oxygen in the dough as it begins a reproduction of cells, dividing the single yeast cell into two cells, which then become four, and redividing continuously into increasingly larger numbers of cells. Trapped in the dough, the yeast cells produce carbon dioxide resulting in the rising of the dough until it reaches a point in size to be burst, reducing it back into its original shape to begin the rising process again. This second rising is faster due to the abundance of cells now present from multiplying continuously.

• Single-cell proteins refer to edible unicellular microorganisms. 
• The biomass or protein extract from pure or mixed cultures of algae, yeasts, fungi or bacteria may be used as an ingredient or a substitute for protein-rich foods and is suitable for human consumption or as animal feeds. 
• Hence, The method of producing proteins for food or feed-through microbial biomass is called as SCP (Single Cell Protein).
• So, the correct answer is 'SCP (Single Cell Protein)'.

Single-cell protein (SCP) refers to sources of mixed protein extracted from pure or mixed cultures of algae, yeasts, fungi or bacteria (grown on agricultural wastes) used as a substitute for protein-rich foods, in human and animal feeds. Single-cell proteins develop when microbes ferment waste materials including wood, straw, cannery and food-processing wastes, residues from alcohol production, hydrocarbons, or human and animal excreta.

It has been demonstrated that Propionibacteria species has the highest potential to accumulate vitamin B$ _{12}$ intracellularly. Propionibacterium shermanii and Propionibacterium freudenreichii are most widely used. Propionibacteria produce vitamin B$ _{12}$ intracellularly and excrete mainly propionic acid and acetic acid extracellularly. All Propionibacterium strains employed for vitamin B$ _{12}$ production are microaerophilic and produce vitamin B$ _{12}$ in high yields only under very low oxygen concentrations.

Plants and animals do not have the capacity to synthesize vitamin B12 by their own. But the microorganisms like Saccharomyces cerevisiae ( contains vitamin B12 but there is no clear answer about the source of synthesizing vitamin B12 in this yeast. But it synthesizes vitamin B12.), acetobacter and also by the mushrooms Agaricus. Thus, the correct answer is option D.

The curdling step in cheese making relies on lactic acid bacteria. These bacteria are able to ferment the carbohydrates found in the milk, releasing lactic acid in the process. The lactic acid causes the proteins dissolved in the milk to precipitate, or come out of solution. When the proteins precipitate, they pull out the fats as well. What you are left with is similar to the sour milk from the introduction: the liquid whey filled with many solid chunks of protein and fat, called curds.

The overall process of fermentation is to convert glucose sugar (C$ _6$H$ _{12}$O$ _6$) to alcohol (CH$ _3$CH$ _2$OH) and carbon dioxide gas (CO$ _2$). The reactions within the yeast to make this happen are very complex but the overall process is as follows: 

Chymosin, known also as rennin, is a proteolytic enzyme synthesized by chief cells in the stomach in young ruminants. Its role in digestion is to curdle or coagulate milk in the stomach, in the very young animal. Chymosin efficiently converts liquid milk to a semisolid like cottage cheese, allowing it to be retained for longer periods in the stomach. It is widely used in the production of cheese. 

Beer is an alcoholic beverage produced by the saccharification of starch and fermentation of the resulting sugar. The starch and saccharification enzymes are often derived from malted cereal grains, most commonly malted barley and malted wheat.

Lactobacillus bacteria have the ability to convert sugars into lactic acid. The Lactobacillus strain is so named because it was first studied in milk ferments. These bacteria readily use lactose or other sugars and convert them quickly and easily to lactic acid.