In bacteria, metabolic energy present in the form of a phosphoesterbond (e. g. ATP or phosphoenolpyruvate [PEP] ) and ion gradients (e. g. H⁺-proton motive force [pmf] or Na⁺ sodium motive force) are used to sustain various biological reactions. The two forms of metabolic energy can be interconverted by FoF1 -ATPases that catalyze the translocation of H+(or Na⁺) concomitant with the hydrolysis/or synthesis of ATP. Nutrient transport by bacteria is usually thought of as consuming such metabolic energy. Over the last ten years, however, a new class of nutrient transport reactions has been identified, one in which substrate transport is virtually used to generate rather than consume energy. The reaction consists of two steps, (i)electrogenic exchange of precursor (amino acids or organic acids) with its intracellular metabolic product (decarboxylation), and (ii) intracellular decarboxylation of the transported precursor. The net charge movement through the precursor: product exchange generates a membrane potential of physiological polarity, and intracellular decarboxylation consumes cytoplasmic protons to generate both a pH gradient of physiological polarity and an outward concentration gradient of the end-product to drive precursor uptake. The combined activities constitute a metabolically-driven proton pump (proton-motive metabolic cycle), allowing cells to display decarboxylative phosphorylation. Thus, it can be recognized as a new class of ATP generation systems besides substrate-level phosphorylation, oxidative phosphorylation, and photo-phosphorylation. The proton motive metabolic cycles would be available for artificial energy-supply systems in various fermentation organisms with recombinant technology.

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To prevent the distribution of foods produced using recombinant DNA techniques whose safety for human consumption has not been assessed, the Government of Japan has ordered a safety assessment to be carried out by the Minister of Health, Labour and Welfare under the Food Sanitation Law of April 1,2001. Under this law it is prohibited to sell and import GM foods whose safety has not been assessed for human consumption. The food sanitation inspectors of the Ministry of Health, Labour and Welfare (MHLW) monitor foods at quarantine stations in order to ensure the safety of imported GM foods for human consumption.

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Effects of the intake of a new fermented milk prepared using Lactobacillus gasseri SBT2055 and Bifidobacterium longum SBT2928, both of human origin, in addition to the yogurt species, Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus on the fecal microflora and related properties were studied in 49 healthy adults (11 men,38 women, average age 41.2years). Administration of 100 g/day of the milk for 15 days improved both the defecation frequency and the fecal properties. Analysis of the fecal microflora in 9 adults (2 men,7 women, average age of 43.4 years) selected from the above volunteers showed increases in the number of Bifidobacterium and its ratio to the total fecal microflora (from 6.2% to 14.5%, p<0.05), thus showing it to be superior to traditional fermented milk prepared with only S. thermophilus and L. delbrueckii subsp. bulgaricus. Administration of 300g/day of the newly prepared fermented milk to five healthy adults (5 men, average age of 48.4 years) for 15 days showed no unfavorable effects. This new fermented milk shows great promise for use as an effective probiotic to improve the intestinal environment in humans.

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