Probiotic bacteria seem to hold great promise as a biotherapeutic agent because of their role in prevention of infectious illness, reinforcing the barrier function of the intestinal flora or strengthening the immune system. Different probiotic species and even different strains exhibit distinctive properties that can markedly affect their survival in foods, fermentation characteristics and other probiotic properties. Acid and bile tolerance of Lactobacillus acidophilus strains make it capable of surviving in the gut. Cholesterol removal property is one of the greatest applications of probiotics exploited. Antimicrobial and antibiotic property explores them further as probiotic. As the bioactivities of probiotics are strain-dependent, biotyping of probiotics is of great importance, especially for the quality control application of approved strains—to avoid health risks and for the description of new species. In the present study, 11 strains of Lactobacillus acidophilus were tested for their acid and bile tolerance, cholesterol removal ability, antimicrobial and antibiotic probiotic properties. The results showed considerable variation among cultures in their growth viability in the presence of acid, bile and removal of cholesterol from the culture medium, antimicrobial and antibiotic properties in vitro. LA 5, strain R showed the best results which indicate that these strains may be promising candidates for use as a dietary adjunct.

Probiotics are defined as “a live microbial supplement that beneficially affects the host animal by improving its intestinal microbial balance” (Fuller, 1989). Shaper et al. (1963) and later Mann (1974) observed that men from the tribes of Samburu and Masai warriors in Africa showed a reduction in serum cholesterol levels after consumption of large amounts of milk fermented with a wild Lactobacillus strain. There has been considerable interest in the beneficial effects of fermented milk products containing Lactobacilli and/or Bifidobacteria on human lipid metabolism. Various studies have indicated that probiotics may alleviate lactose intolerance, have a positive influence on the intestinal flora of the host, stimulate/modulate mucosal immunity, reduce inflammatory or allergic reactions, reduce blood cholesterol, possess anticolon cancer effects, diarrhea, constipation, candidasis and urinary tract infections and competitively exclude pathogens (Bhatia and Pawan, 2010).

The public interest in cholesterol has increased owing to awareness and publicity of the relationship of serum cholesterol to the risk of developing coronary heart disease and also of inducing colon cancer, in addition to high dietary fat and low fiber (Reddy et al., 1977; Law et al., 1994; and Baroutkoub et al., 2010). Even a small reduction of 1% in serum cholesterol was found to reduce the risk of coronary heart disease by 2 to 3% (Manson et al., 1992). Several methods have been developed to reduce cholesterol in foods by using various physical, chemical and biological procedures (Micich, 1990; Lee et al., 1999; and Sedaghat et al., 2010). The capability of the probiotics incorporated into foods to inhibit the growth or even kill certain pathogens confirms the health benefits one derives from the consumption of these products. However, with the emergence of a more health-conscious society, the role of biological procedures (probiotic food products) has gained considerable attention from both producers and consumers, raising an alternative source of medicine.

Biotechnology Journal, Stress Adaptation of Bacteria, Extremophiles, Bacterial Adaptation, Cytosolic Components, Denature Cellular Proteins, Reactive Oxygen Species, Monounsaturated Fatty Acids, Ultraviolet Radiation, Environmental Stress, Stress Management, Biological Systems, Cellular Economy.