Abstract: By administering sterilized bacterial cells obtained by heat treating cells of a coryneform bacterium or an enterobacterium under a condition of pH 2 to 5 at 90 to 120° C. for 3 minutes to 4 hours, or a feed containing such sterilized bacterial cells to a mammal, fowl, fish, or crustacean, immunity of these animals is enhanced.

Abstract: An Escherichia bacterium having dihydrodipicolinate synthase and aspartokinase, both of which are desensitized to feedback inhibition by L-lysine. The intracellular activity of dihydrodipicolinate reductase in this bacterium can also be enhanced. Furthermore, a diaminopimelate dehydrogenase gene can be introduced into this bacterium, or intracellular activities of tetrahydrodipicolinate succinylase and succinyl diaminopimelate deacylase can be enhanced. Finally, the intracellular activities of aspartate-semialdehyde dehydrogenase or phosphoenolpyruvate carboxylase can be enhanced in this bacterium. The bacterium can be cultured in a suitable medium to produce and accumulate L-lysine in culture, and the L-lysine is collected from the culture.

Abstract: An Escherichia bacterium having dihydrodipicolinate synthase and aspartokinase, both of which are desensitized to feedback inhibition by L-lysine. The intracellular activity of dihydrodipicolinate reductase in this bacterium can also be enhanced. Furthermore, a diaminopimelate dehydrogenase gene can be introduced into this bacterium, or intracellular activities of tetrahydrodipicolinate succinylase and succinyl diaminopimelate deacylase can be enhanced. Finally, the intracellular activities of aspartate-semialdehyde dehydrogenase or phosphoenolpyruvate carboxylase can be enhanced in this bacterium. The bacterium can be cultured in a suitable medium to produce and accumulate L-lysine in culture, and the L-lysine is collected from the culture.

Abstract: An Escherichia bacterium (1) which harbors dihydrodipicolinate synthase of which feedback inhibition by L-lysine is desensitized and aspartokinase of which feedback inhibition by L-lysine is desensitized, (2) in which intracellular activity of dihydrodipicolinate reductase is enhanced, and (3) in which a diaminopimelate dehydrogenase gene is introduced or intracellular activities of tetrahydrodipicolinate succinylase and succinyl diaminopimelate deacylase are enhanced, wherein intracellular activity of aspartate-semialdehyde dehydrogenase or phosphoenolpyruvate carboxylase is enhanced, is cultured in a suitable medium to produce and accumulate L-lysine in culture, and the L-lysine is collected from the culture.

Abstract: A hydrolyzed protein which can be used as seasonings or the like is produced by heating and maintaining an aqueous dispersion of a protein-containing starting material, while under an acidic condition, with a plate-type heat exchanger using a liquid as a heat medium to make the aqueous dispersion substantially aseptic and then subjecting the resulting aqueous dispersion with an action of a proteolytic enzyme.

Abstract: A hydrolyzed protein which can be used as seasonings or the like is produced by heating and maintaining an aqueous dispersion of a protein-containing starting material, while under an acidic condition, with a plate-type heat exchanger using a liquid as a heat medium to make the aqueous dispersion substantially aseptic and then subjecting the resulting aqueous dispersion with an action of a proteolytic enzyme.