The rice herbicide cafenstrole and its analogs inhibited the incorporation of [l-1 4 C]-oleate and [2-1 4 C]-malonate into very-long-chain fatty acids (VLCFAs), using Scenedesmus cells and leek microsomes from Allium porrum. Although the precise mode of interaction of cafenstrole at the molecular level is not completely clarified by the present study, it is con cluded that cafenstrole acts as a specific inhibitor of the microsomal elongase enzyme in volved in the biosynthesis of fatty acids with alkyl chains longer than C18. For a strong VLCFA biosynthesis inhibition an -S 0 2-linkage of the 1,2,4-triazole-l-carboxamides was required. Furthermore, /V,./V-dialkyl substitution of the carbamoyl nitrogen and electron-donating groups such as methyl at the benzene ring of 1,2,4-triazole-l-carboxamides produced a strong inhibition of VLCFA formation. A correlation was found between the phytotoxic effect against barnyardgrass (Echinochloa oryzicola) and impaired VLCFA formation.

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Indanofan and its analogs inhibited the elongation of stearoyl- or arachidoyl-CoA by [2-14C]-malonyl-CoA in leek microsomes from Allium porrum. Although the precise mode of interaction of indanofan at the molecular level is not completely clarified by the present study, it is concluded that indanofan and analogs act as inhibitor of the elongase enzyme involved in de novo biosynthesis of fatty acids with an alkyl chain longer than C18, called very-long-chain fatty acids (VLCFAs). For a strong inhibition of VLCFA formation chloro substituents at the benzene ring and the oxirane group were necessary. Furthermore, the greenhouse test showed strong activity for indanofan and its analogs, and the scores coincided with cell-free elongation inhibition. The cell-free assay, however, failed to indicate any activity for an analog having a methylene instead of the oxirane group, while both Digitaria ciliaris and Echinochloa oryzicola were killed with 1 kg a.i./ha. This finding cannot be discussed because the applied use rate of 1 kg a.i./ha is too high to allow for a score differentiation. For high concentrations of this compound additional unknown inhibitory effects may be involved besides fatty acid elongation.

The relation between oleate and biotin to the extracellular accumulation of L-glutamate in Microbacterium ammoniaphilum was studied. And it was suggested that oleate was the essential constituent for the bacterial cell structure, and, at the same time, it participated in the cellular permeability of L-glutamate. On the other hand, biotin was recognized to play a role on the synthesis of cellular fatty acid, main! y oleate and palmitate. Through the discussion above mentioned, the reason was made clear that biotin was not necessary for the bacterial growth or the extracellular accumulation of L-glutamate, if oleate had been added.

Twenty-two strains of L-glutamate non-producing bacteria and L-glutamate producing bacteria were compared with respect to the following properties, which seem to be related to L-glutamate formation.The results obtained are as follows: (1) As for the activity of L-glutamate dehydrogenase, almost all of the L-glutamate non-producing bacteria tested showed little activity, whereas Brevibacterium ammoniagenes ATCC 6871, Corynebacterium equi IAM 1038 and Corynebacterium fasciens IAM 1079 exhibited rather strong abilities, though not so conspicuous as L-glutamate producing bacteria did. (2) As for the amount of intracellular free L-glutamate, only new strain No. 145 contained it more than L-glutamate producing bacteria did. (3) As for the cellular fatty acid composition, Sarcina lutea IFO 3232 and Brevibacterium ammoniagenes ATCC 6871 had the similar composition to that of L-glutamate producing bacteria.L-Glutamate producing ability of these strains which showed resemblance to L-glutamate producing bacteria will be examined in the following paper.