Towards internationalization of Agrobiotechnology Research between University of São Paulo (USP), Brazil, and University of Natural Resources and Life Sciences (BOKU), Austria

Abstract

The use of probiotic microorganisms in animal nutrition has been investigated as an efficient alternative to the use of antibiotics as growth promoters. In addition, recent studies have shown that certain substances produced by these microorganisms, such as bacteriocins, vitamins, fatty acids, exopolysaccharides, enzymes, among others, improve the immunity and development of their hosts. The probiotic action is therefore not only restricted to the addition of suitable microorganisms, but also the improvement of the absorption conditions in the lumen. The most commonly used probiotic microorganisms in the food and pharmaceutical industries are those belonging to the lactic acid bacteria group (LAB), since they are considered safe by regulatory agencies in this area. However, it is known that the beneficial effects generated by probiotics are specific to each host and, frequently, interest compounds are synthesized in greater quantity by a given bacterial strain. Beside the acidic condition create by these microorganisms, they also produce several antimicrobial substances such as hydrogen peroxide, ethanol, diacetyl, carbon dioxide and bacteriocin, which may confer to them the potential effect as a probiotic. Bacteriocins are peptides synthesized in the ribosome and are produced by a wide variety of bacteria, including LABs, which have a broad spectrum of action against Gram-positive and Gram-negative bacteria, protozoa, fungi and viruses, thereby behaving effectively in the gastrointestinal tract. Pediococcus genus colonize the gastrointestinal tract and are considered probiotics, because they inhibit the growth of intestinal pathogens by stimulating the immune system, reducing total and LDL cholesterol levels and improving protein digestion, hence leading to an increase in the absorption of vitamins and minerals. This genus is composed of Gram-positive homofermentative, motile, non-spore-forming and facultative anaerobic cocci, which are usually organized in tetrads, have complex nutritional requirements and grow under microaerophilic and occasionally anaerobic conditions because of their limited respiratory capacity. To increase the antimicrobial activity of these peptides, the ability of LABs to ferment different carbon and nitrogen sources has been studied. In fact, to achieve the best performance and obtain the desired product, there is a need for selection of these sources to improve the process conditions and provide adequate supply to the cells for biosynthesis and energy generation. In addition, if feed is one of the most important cost factors in the production of biomolecules by fermentation, the composition of culture medium must be carefully defined. (AU)