Stereospecific sulfur oxidation of 7-methylthioxanthone-2-carboxylic acid by Calonectria decora.

Thin-layer chromatography was used to determine the ability of three microorganisms capable of sulfur oxygenation, including Aspergillus niger, Streptomyces armentosus subsp. armentosus, and Calonectria decora, to oxidize 7-methylthioxanthone-2-carboxylic acid to the corresponding sulfoxide in growing cultures. In addition, optical rotary dispersion, circular dichroism, and nuclear magnetic resonance analysis in the presence of chiral shift reagent were used variously to access reaction stereoselectivity, absolute configuration, and optical purity of isolated products. The data indicated that C. decora produced the sulfoxide in high yield (69%) and optical purity (97%), most probably in the S-configuration.

Microbiological hydroxylation of carbons 18 and 19 in 9-oxo-13(cis and trans)-prostenoic acids.

dl-9-Oxo-13 (cis and trans)-prostenoic acids were converted in high yields into their 18- and 19-hydroxy derivatives by cultures of Microascus trigonosporus. The structure elucidation of the microbial products is described.

Microbial reduction of 1,3-dioxo-2-methyl-2-(3'0oxo-6'-carbomethoxyhexyl)-cyclopentane to form 1 beta-hydroxy-3-oxo-2beta-methyl-2alpha-(3'-oxo-6'-carbomethoxyhexyl)-cyclopentane, an intermediate for steroid total syntheses.

The rate and extent of stereoselective reduction of 1,3-dioxo-2-methyl-2-(3'-oxo-6'-carbomethoxyhexyl)-cyclopentane to form the 1beta-hydroxy-2beta-methyl isomer by cultures of Schizosaccharomyces pombe ATCC 2476 was dramatically increased by addition to the fermentation of certain alpha,beta-unsaturated ketones and allyl alcohol.

Microbial reduction of ketopantoyl lactone to pantoyl lactone.

The results of a microbial survey study have shown that the ability to reduce added ketopantoic acid (or ketopantoyl lactone) and accumulate pantoic acid (or pantoyl lactone) in the growth medium is widespread among diverse fungi. The reductions generally proceeded with less than full stereoselectivity. However, specific strains of the ascomycete Byssochlamys fulva were found to form D[-]-pantoic acid in unusually high yields and optical purity.

Herbicide transformation. I. Studies with whole cells of Fusarium solani.

A strain of Fusarium solani isolated from soil by enrichment techniques used propanil (3', 4'-dichloropropionanilide) as a sole source of organic carbon and energy for growth in pure culture. The primary product of the transformation of propanil by F. solani was isolated and identified as 3,4-dichloroaniline (DCA). This compound accumulated in the medium to a level (80 mug/ml) which stopped further herbicide utilization. Herbicide utilization by F. solani was influenced by various environmental and nutritional factors. It was more sensitive to acid than alkaline pH. Added glucose and yeast extract increased the rate of propanil decomposition, and the reduced aeration retarded growth of the fungus and herbicide utilization. The growth of F. solani on propionate was inhibited by added DCA.

Herbicide transformation. II. Studies with an acylamidase of Fusarium solani.

Replacement cultures liberated 3,4-dichloroaniline (DCA) from 3,4-dichloropropionanilide (propanil). The kinetics of the conversion suggest a requirement for de novo enzyme synthesis, but the system was not influenced by chloramphenicol or puromycin. Enzyme activity was detected when acetanilide (K(m) = 0.195 mm) was used to replace propanil as substrate. Fungal acylamidase (E.C. 3.5.1., an aryl acylamine amidohydrolase) was concentrated by salt precipitation and characterized. The Fusarium solani acylamidase exhibited an optimum at pH 7.5 to 9.0 and was inactivated in 10 min at 50 C. The enzyme was not sensitive to methyl-carbamate or organophosphate insecticides, but the herbicide, Ramrod (N-isopropyl-2-chloroacetanilide), acted as a competitive inhibitor of acetanilide hydrolysis (K(i) = 0.167 mm). Hydrolysis rates were decreased by various para substitutions of acetanilide. Chloro substitution in the acyl moiety of acetanilide also reduced the rate of hydrolysis. 3,4-Dichloroacetanilide was less susceptible to enzyme action than acetanilide, but 3,4-dichloropropionanilide was hydrolyzed much more rapidly than propionanilide. The fungal acylamidase was highly specific for N-acetylarylamines. It did not catalyze hydrolysis of formanilide, butyranilide, dicryl, Karsil, fenuron, monuron, or isopropyl-N-phenylcarbamate. It appears to differ from acylamidases that have been isolated from rice, rat liver, chick kidney, and Neurospora.

Stability and effects of some pesticides in soil.

The influence of 29 pesticides on CO(2) production and nitrification by soil microorganisms was determined. A few compounds were stable but without significant effect in soil (chlorinated hydrocarbons), some persisted and depressed respiration and nitrification (carbamates, cyclodienes, phenylureas, thiolcarbamates), and others displayed toxicity but were transformed by soil microorganisms (amides, anilides, organophosphates, phenylcarbamates, triazines). Some compounds of the last type induced an initial increase and subsequent decrease in CO(2) production by soil. No simple explanation of this effect is possible, but the results of studies of model systems having established activities suggest that in soil any one or a combination of the following mechanisms is responsible for the observed complex relation of CO(2) production to time: (i) a pesticide acts to uncouple oxidative phosphorylation in a manner analogous to 2,4-dinitrophenol; (ii) a pesticide lacking antimicrobial action is oxidized in part and transformed to a stable and toxic product; (iii) a pesticide that is selectively toxic inhibits CO(2) production by sensitive microorganisms but is subject to oxidation without detoxification by other members of the microbial population that are resistant to its initial action. Pesticide concentrations greatly in excess of those recommended for agricultural and home use were required to produce an effect, and supplementary organic matter (glucose) tended to reduce pesticide toxicity and increase the microbial degradation of pesticides in soil.