Abstract: A microorganism, which has an ability to produce L-amino acid, especially L-phenylalanine, L-tryptophane, L-tyrosine, L-threonine, or L-isoleucine, in which a phosphoenolpyruvate-producing ability is enhanced, is cultivated in a medium so that the L-amino acid is produced and accumulated in the medium to collect the L-amino acid.

Abstract: An L-isoleucine-producing bacterium belonging to the genus Escherichia which carries a thrABC operon which comprises a thrA gene coding for aspartokinase I-homoserine dehydrogenase I substantially released from the inhibition by L-threonine and an ilvGMEDA operon which comprises an ilvA gene coding for threonine deaminase substantially released from the inhibition by L-isoleucine and whose region required for attenuation is removed; and an L-isoleucine-producing bacterium belonging to the genus Escherichia carrying the thrABC operon, an lysC gene coding for aspartokinase III substantially released from the inhibition by L-lysine, and the ilvGMEDA operon. The bacteria permit biosynthesis of a sufficient amount of L-isoleucine.

Abstract: This invention relates to novel carboxylic acid esters represented by the formula (I) below, methods for their production and insecticides and/or acaricides containing them as an active ingredient, ##STR1## wherein R.sup.1 represents a C.sub.1-5 alkyl group, a C.sub.2-4 alkenyl group or a C.sub.2-4 alkynyl group; R.sup.2 represents a fluorine atom or a methyl group; and R.sup.3 represents a hydrogen atom or a methyl group.