%0 Journal Article
%T A Review on Some Chemical Engineering and Microbiological Aspects Considered in the Production of Highly Concentrated Probiotic Cultures and Bacteriocins by Lactococci and Lactobacilli
%A Nelson P¨Śrez Guerra
%J ISRN Chemical Engineering
%D 2012
%R 10.5402/2012/836381
%X The main purpose of this work is to give an overview on the chemical engineering aspects related with the production of probiotic cultures and bacteriocins. Firstly, some evidence of the potential of different Lactococci and Lactobacilli strains for prevention or treatment of different human diseases, or as growth promoters in farm animals is given. In addition, examples of different commercial dietary supplements containing probiotic lactoccocci and lactobacilli in combination or not with other probiotic bacteria are presented. Secondly, the main factors (cultivation method, culture media, and media composition) affecting the production of bacteriocins by lactoccocci and lactobacilli strains are showed. Examples of modelling procedures developed to describe the production of higher concentrations of biomass and bacteriocins in fed-batch cultures subjected or not to successive alkalizations are summarized. Finally, the corresponding mass balance equations performed in the latter cultures are presented to calculate the volumes of feeding substrates and the concentrations of nutrients (lactose, glucose, proteins, nitrogen, and phosphorous) added to the fermentation medium, as well as the concentrations of biomass and products in the fermentor just after each feeding. 1. Main Characteristics of Probiotics Probiotics are viable microorganisms that, once ingested in sufficient amounts, exert health-promoting effects in humans and animals by assisting in the establishment of an intestinal population which is beneficial to the host entity and antagonistic to harmful bacteria [1¨C4]. This beneficial effect is commonly related with the elimination of pathogens by stimulating the immune system, by colonizing the gut in large numbers (competitive exclusion), and/or by the production of antimicrobial substances, including organic acids and bacteriocins [5, 6]. Thus, since the extensive use of antimicrobials (e.g., antibiotics and silver sulphadiazine) could produce adverse reactions and side effects [7, 8], the interest has been focussed on the use of probiotics for preventing or treating different human diseases [1, 4] and for improving the performance parameters of farm animals. These probiotics can play an important role in immunological, digestive, and respiratory functions in humans [9] and can improve the body weight gain and feed conversion in farm animals [2, 3]. The probiotic strains must be: (i) safe, noninvasive, nonpathogenic, nontoxic, and noncarcinogenic; (ii) resistant to gastric acidity and bile toxicity, which is an important characteristic for
%U http://www.hindawi.com/journals/isrn.chemical.engineering/2012/836381/