Bacteria inhabit the intestines and protect against some unhealthy organisms. Forsgren et al (2010) demonstrated the use of novel lactic acid bacteria inhibits the growth of pathogen in honey bee larvae. Furthermore, they also demonstrated that the addition of LAB to young honey bee larvae exposed to P. larvae spores decreases the proportion of larvae that succumb to American Foul Brood infection. The breakdown of food by L. acidophilus produces lactic acid, hydrogen peroxide, and other byproducts that make the environment hostile for undesired organisms. Thus Lactobacillus are also known to inhibit the growth of major honey bee pathogens (Promnuan et al., 2009; Audisio et al., 2010; Forsgren et al., 2010). Treatment by formic, lactic, and acetic acid is widely employed by beekeepers to guard against such honeybee pathogens as Varroa destructor and Nosema apis. Organic acids such as formic acid, which is produced by bifidobacteria(Van der Meulen et al, 2006), and both lactic and acetic acid, which are produced by LAB discovered in the honey stomach are antimicrobial substances, meaning that these bacteria may be of considerable importance in protecting honeybees against pathogens.
    It is also well known that Lactobacillus spp., produce antimicrobial substances (Kim et al., 1997). These facultative anaerobes tolerate the acidic environments and ferment sugars to produce lactic or acetic acid. The production of lactic acid makes the environment acidic which inhibits the growth of some harmful bacteria. These bacteria could be cultured as microbial food supplement, which benefits the host by improving its intestinal microbial balance (Fuller, 1989). These beneficial bacteria have a role to play in disease control/prevention, enhancement of growth rates, and nutrition. These right microbes could be used to inoculate the hive and the bee gut to aid colony health and diet. The midgut of honeybees is the only part of the alimentary tract, which is not lined by chitin, and thus is extremely exposed to toxic substances and improper food.      The colonization of bee intestine by bacteria such as Lactobacillus spp. and yeasts is a very important process; the micro-organisms participate not only in food digestion but also in the production of vitamins and antibiotic substances which eliminate pathogenic micro-organisms (Tomasik & Tomasik, 2003). In order to create a proper microfloral environment in the bee intestine, pollen substitutes need to be supplemented with microorganisms, which colonize the alimentary tract and determine proper digestion.

Full article