The intake of probiotics such as bifidobacteria and lactobacilli has been known to prevent and alleviate allergy and infection. These physiological effects are thought to arise from the immunomodulatory effects of probiotics on immunological parameters such as cytokines. However, it is not fully understood how probiotics modulate the immunological parameters of the host. In this study, we investigated the effects of bifidobacteria on the in vitro production of cytokines and chemokines related to allergic developments. In addition, we studied the mechanism of action using the strain Bifidobacterium longum BB536, which has been shown to have anti-allergic and anti-infective properties in clinical studies. We also examined the clinical effects of B. longum BB536 on anti-infection-related immunological parameters.

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Antimicrobials in animal feed have been used for a long time as a standard supplement in the intensive farming of livestock. In recent years, however, some of the antimicrobials have been banned by statute. Therefore, the use of probiotics in the animal farming industry, is expected to become economically viable, as a potential alternative to antimicrobials, because of their positive effects on animal health and growth performance. It is required that new product development in this field makes cost-benefit calculations in addition to scientific research concerning the physiological effects of probiotics and their mechanisms. In this context, the market trends of feedstuffs and the animal products, and the environmental impact of animal farming should be studied for each type of products. Probiotics are expected by farmers to raise the quality of their products which may further contribute to the economic benefit of the farm, and it will be difficult to increase the adoption rate of probiotic goods in the animal industry, if they do not meet all the economic requirements of the farmer. In addition to the economic aspects, further scientific research should be conducted of the mechanisms behind the beneficial effects of probiotics for livestock. Farm animals are evolutionary very distant from common experimental animals, such as mice and rats, and it is difficult to generalize research evidence obtained from experimental animals to livestock.

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The molecular tool targeting the 16S ribosomal RNA gene is a powerful tool for elucidating the structure and function of bacterial communities. Here we give an outline of T-RFLP and its related techniques, mainly our devised one, as well as research findings that have been obtained using the T-RFLP. Moreover, we present research findings obtained using T-RFLP that are consistent with those obtained using next generation sequencers that have recently come into widespread use. We also discuss the future uses of the T-RFLP.

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It takes one to several days to determine the number of viable microbial cells by plate count analysis. Microcolony analysis is based on plate count analysis, and is used to detect the early stage of colony formation by staining with a fluorescent dye and observation under a fluorescence microscope. Using this method, it is possible to measure the number of bacteria with growth ability in a short time. As this analysis collects bacteria by filtration, it is used to measure the number of viable bacteria in liquid samples rather than solid samples containing insoluble materials. We usually use the plate count analysis to count the number of viable bacteria in solid commercial products such as pharmaceuticals and quasi drugs. However, a more rapid, accurate and simple technique is required. In this study, we investigated the feasibility of microcolony analysis for the quantification of viable bacteria in solid products, and obtained the following results. 1. SYTO^®9 is an optical fluorescent dye which can be used to prevent the staining of nonspecific insoluble excipients in products. 2. When the samples were centrifuged for 5 min at 150×g, the insoluble excipients were mostly removed. Therefore, it became possible to prevent the collapse of the shape of microcolonies. 3. The number of viable bacteria was accurately estimated when the microcolonies were counted in over 10 microscopic fields with 5×objective. Under these measurement conditions, we demonstrated that microcolony analysis can determine more rapidly and accurately than plate count analysis the number of viable bacteria in a Bifidobacterium solid product as well as several commercial products. In conclusion, we have demonstrated that modified microcolony analysis can be used as an alternative analysis to plate count analysis.

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