Biodiversity and Biotechnological Process

Question: Discuss about the Biodiversity and Biotechnological Process. Answer: Introduction: Kluyveromyces marxianus is a yeast species that was earlier called Kluyveromyces fragilis. The yeast has roles in cheese ripening, as a probiotic that boosts immunity and as an inoculum for whey, a dairy by-product to produce several bio-ingredients. It is a versatile yeast and can utilize a variety of substrates, its rate of growth is rapid and it can grow well at temperatures up to 400 C. The organism is generally regarded as safe and is therefore appropriate for fermentations in the food and pharmaceutical industries (Fonseca, et al., 2007). K. marxianus is an aerobic respiring and Crabtree negative yeast. Kluyveromyces marxianus plays a key role in the ripening of cheese along with other yeasts of importance in the dairy industry that include Kluyveromyces lactis, Yarrowia lipolytica, and Debaryomyces hansenii. The yeasts ferment lactose and increase the pH by utilizing the lactic acid produced during fermentation. The yeasts also release enzymes that are lipolytic, proteolytic and autolytic. The rise in pH allows acid-sensitive bacteria to act on the cheese during the process of ripening. The main distinctive feature of K. marxianus is that it produces the enzyme -galactosidase even in the absence of lactose (Tofalo, et al., 2014). The yeast Kluyveromyces marxianusis is a versatile organism and is employed for a variety of applications in the industry. It is used in the production of ethanol, cell protein, bioingredients, inulinase, lactase, lipase, pectinase and aromatic compounds (Fonseca, et al., 2007). An important application of the yeast is in reducing lactose content of various food products. Important applications of K. marxianus have been proposed in the production of oligonucleotides that can be used as flavour enhancers. The production of oligosaccharides from whey for use s prebiotics can help to stimulate the growth of Bifidobacterium sp. in human intestines. The proteolysis of whey protein can yield oligopeptides that can act as immunostimulators (Belem Lee, 1998). Kefir and koumiss are fermented milks that contain the lactose fermenting yeast K. marxianus (Kumura, et al., 2004). The presence of microorganisms in kefir prevents the spoilage and the development of pathogenic bacteria due to presence of antibiotics and bctericidal compounds in kefir. It is therefore consumed for treatment of diarrhoea caused by Clostridium difficile. Kefir inhibits formation of Aspergillus flavus and the formation of aflatoxin B1. Its role in food preservation is considered to be important (Prado, et al., 2015). While K. marxianus is an important yeast in the ripening of cheese, it is known to cause defects in flavour and texture of the soft cheeses. It can deteriorate the quality of some cheeses and make them gassy due to the production of fermentative gases(Boekhout Robert, 2003). It is interesting to note that the same species of yeast can contribute to the ripening of one kind of cheese on one hand and cause the spoilage of other kinds of cheese on the other hand. marxianus is an yeast species that has been employed for several applications in the dairy and food industries. It has been used to ripe cheese, ferment milk to form kefir and koumiss and for the production of several enzymes. Lactic acid bacteria Lactic acid bacteria are found adventitiously in natural milk and have been used to produce several dairy products that involve fermentation of milk. The lactic acid is produced due to the fermentation of the milk sugar- lactose into lactic acid. The production of lactic acid lowers the pH of milk and results in the separation of milk proteins from whey. The reduced moisture of milk proteins and the lowering of pH helps to prevent the spoilage of milk proteins. The whey can be removed and the milk solids can be processed further to form cheese. Curd, yoghurt, ayran, kefir and koumiss are traditional and industrially produced fermented milk products that employ the lactic acid bacteria for the fermentation of milk. Certain species of yeasts may also play a role in the formation of these products. The production of bacteriocins by the lactic acid bacteria further protects the fermented milk products from spoilage or the growth of pathogens (Cogan, et al., 1997). The production of lipases, proteases and exopolysaccharide are characteristics of lactic acid bacteria that help in cheese making. The several amino acids required for the growth of starter culture become available through the breakdown of the milk protein. Since lactic acid bacteria fall in the category of generally regarded as safe bacteria, the bacteriocins produced are broad- spectrum and are widely employed in the food industry. Bacteriocins that remain stable at higher temperature and can remain active at low pH are particularly useful in the food processing industry. The exopolysaccharides produced by lactic acid bacteria are useful in production of fermented milks such as, kefir and ayran. Lactic acid bacteria through the process of fermentation, help to prolong the shelf life of milk which is highly perishable. Some examples of Lactic acid bacteria include Lactobacillus casei, Lactobacillus rhamnosus and Lactobacillus lactis. Lactic acid bacteria used for preparation of yoghurt are Streptococcus thermophilus and Lactobacillus bulgaricus. Lactic acid bacteria used for the production of cheese include both mesophilic and thermophilic bacteria. The mesophilic genera are Lactococcus and Leuconostoc while Streptococcus thermophilus and Lactococcus lactis are genera that are thermophilic. The flavours of yoghurt and cheese are imparted by the lactic acid bacteria. Bacterial or yeast species that cause ripening of cheese also play a role in imparting flavour and developing the texture of the cheese. The probiotic properties of lactic acid bacteria pro vide several health benefits. Lactic acid bacteria fermented milk products are consumed all over the world, some examples include, Kumis (Columbi), Maasai and Susaac (Kenya), Lben (Morocco) and Ayran (Turkey).Since fermented milk products are rich in Calcium, these are an important component of food (Widyastuti, et al., 2014). Some products help in lowering cholesterol and treating conditions like diarrhoea. The lactic acid bacteria are therefore useful in prolonging shelf life of milk, prepartion of probiotic foods, production of bacteriocins that can stop the growth of spoilage bacteria or pathogenic microorganisms. The use of lactic acid bacteria in preparation of ethnic foods and as commercial inocula or starter cultures has long been practised. Development of newer fermented foods also employs LABs. References Belem, M. Lee, B., 1998. Production of Bioingredients From Kluyveromyces Marxianus Grown on Whey: An Alternative. Critical Reviews in Food Science and Nutrition, 38(7), pp. 565-598. . Boekhout, T. Robert, V., 2003. Yeasts in Food. 1 ed. s.l.: Behr's Verlag, . Cogan, T. et al., 1997. Characterization of the lactic acid bacteria in artisanal dairy. Journal of Dairy Research , Volume 64, pp. 409-421. Fonseca, G., Gombert, A., H. E. Wittmann, C., 2007. Physiology of the yeast Kluyveromyces marxianus during batch and chemostat cultureswith glucose as the sole carbon source. FEMS Yeast Research, Volume 7, pp. 422-435. Kumura, H. et al., 2004. Screening of Dairy Yeast Strains for Probiotic Applications. Journal of Dairy Science, Volume 87, p. 40504056. Prado, M. et al., 2015. Milk kefir: composition, microbial cultures, biological activities, and related products. Frontiers in Microbiology, Volume 6, p. 1177. Tofalo, R. et al., 2014. The predominance, biodiversity and biotechnological properties of Kluyveromyces marxianus in the production of Pecorino di Farindol cheese. International Journal of Food Microbiology , Volume 187, p. 4149. Widyastuti, Y., Rohmatussolihat Febrisiantosa, A., 2014. The Role of Lactic Acid Bacteria in Milk Fermentation. Food and Nutrition Sciences , Volume 5, pp. 435-442.