Fumiki Yoshizako

Microbial reduction of 2-norbornanone by Chlorella

Abstract Algal transformation of racemic norbornanone [(±)-2-norbornanone] by Chlorella pyrenoidosa Chick was investigated. (±)-2-Norbornanone was preferentially reduced to (−)-endo-norborneol which was obtained as a product containing 8% of exo-isomer, with a constant rate of endo- vs. exo-alcohol (82:18) in the media detected up to 48 h. The yield and accumulation ratio of the alcohols were not affected over the 5.5 to 10.5 pH range tested. Addition of allyl alcohol inhibited the yields of endo-norborneol more efficiently than that of exo-isomer. Differences in the reductive activity of (±)-2-norbornanone were observed among three strains of Chlorella in which C. pyrenoidosa Chick possessed the highest activity.

Identification of algal transformation products from alicyclic ketones

Abstract Algal transformations of four alicyclic ketones were photoautotrophically studied with an axenic strain of Chlorella pyrenoidosa Chick. The algal reduction of 2-, 3- and 4-methylcyclohexanones, and 4- tert -butyl-cyclohexanone to form the corresponding cis - and trans -alcohols were confirmed by GC-MS analysis. The cis/trans ratios of the resulting cyclohexanols were different from those obtained by reduction with Aspergillus repens . The ratio of cis -isomer to trans -one of 3-methylcyclohexanol was especially large (20:1).

Metabolism of n-alkylcyclohexanes with an even number of carbon atoms in the side chain by Micrococcus sp. RCO-4M

The metabolism of n-alkyleyclohexanes with an even number of carbon atoms (6, 8, 10, 12, 14) in the side chain by Micrococcus sp. RCO-4M was investigated. Evidence for the formation of cyclohexanecarboxylic acid (I), cyclohexaneacetic acid (II), 1-cyclohexenecarboxylic acid (III), 6-hydroxyhexanoic acid (IV), adipic acid (V), and trans-4-hydroxycyclohexaneacetic acid (VI) is presented. The presence of products (II), (IV) and (V) especially represent the complete degradation of n-alkylcyclohexanes with an even number of carbon atoms in the side chain by a single organism. The occurrence of a newly-identified product (VI) suggests that a new metabolic pathway for n-alkylcyclohexanes with even-carbon-number side chain operates in this organism.

Microbial reduction of cyclohexanone by Chlorella pyrenoidosa chick

Algal transformation of cyclohexanone (C6ON) was photoautotrophically studied with an axenic strain of Chlorella pyrenoidosa Chick. The algal reduction of C6ON to cyclohexanol (C6OL) was confirmed by GC-MS analysis, but C6OL could not be further transformed by this strain. Three cycloalkanones, cyclopentanone, cycloheptanone, and cyclooctanone, were also converted to their corresponding alcohols in a growing culture of the same strain. The pH of the medium did not influence the algal reduction of C6ON to C6OL, although increasing C6ON concentrations resulted in a decrease in cell growth. The maximum accumulation of C6OL in growing culture was observed at 0.2% C6ON.

Asymmetric reduction of methyl 3-oxopentanoate by Chlorella

Abstract Chlorella pyrenoidosa Chick catalyzed the reduction of methyl 3-oxopentanoate (Me 3-oxoPen) to the corresponding (S)-(+)-3-hydroxy ester in 60% enantiomeric excess (ee). An improvement of the ee of (S)-(+)-3-hydroxy ester was achieved by increasing substrate concentration and by the addition of 1% metal salts, namely, NaCl and KCl (75–78% ee). No shift of ee toward the (R)-(−)-3-hydroxy ester was observed following this addition. The addition of allyl alcohol brought about a decrease in both the chemical yields and the ee of (S)-(+)-3-hydroxy ester. Differences in the ability to reduce me 3-oxoPen were observed among three strains of Chlorella, of which C. pyrenoidosa Chick yields the (S)-(+)-3-hydroxy ester but C. regularis and C. vulgaris Beijerinck yield (R)-(−)-enantiomer. In particular, C. regularis transformed Me 3-oxoPen to (R)-(−)-3-hydroxy ester in 79% ee, with a 10% yield.

Biotransformation of cyclic β-keto esters by Chlorella pyrenoidosa Chick

Abstract Algal transformations of three cyclic β-keto esters, methyl 2-oxocyclopentanecarboxylate (MCPC), ethyl 2-oxocyclohexanecarboxylate (ECHxC), and methyl 2-oxocycloheptanecarboxylate (MCHpC) were photoautotrophically studied with an axenic strain of Chlorella pyrenoidosa Chick. The three cyclic β-keto esters were transformed in two manners; reduction of the carbonyl group to a hydroxy group and elimination of the alkoxycarbonyl group. The former reaction occurred more often than the latter. The cis/trans ratios of the resulting alcohols in MCPC, ECHxC and MCHpC were 13 : 87, 15 : 85, and 65 : 35, respectively. The alkoxycarbonyl group elimination products were as follows: cyclopentanone and cyclopentanol in MCPC, cyclohexanone and cyclohexanol in ECHxC, and cycloheptanone in MCHpC.

Bioconversion of cyclohexaneacetic acid to monohydroxycyclohexaneacetic acids by Chlorella pyrenoidosa chick

Abstract Algal conversion of cyclohexaneacetic acid was studied with five axenic strains of Chlorella ; in two Chlorella pyrenoidosa strains, cyclohexaneacetic acid was transformed to three monohydroxycyclohexaneacetic acids. As biotransformation products, cis - and trans -3-hydroxycyclohexaneacetic acid and trans -4-hydroxycyclohexaneacetic acid were identified by gas chromatography-mass spectrometry.

Purification and Properties of a Carbonyl Reductase Involved in Stereoselective Reduction of Ethyl 4-Chloro-3-oxobutanoate from Cylindrocarpon sclerotigenum IFO 31855

A NADPH-dependent carbonyl reductase (CSCR1) was purified to homogeneity from Cylindrocarpon sclerotigenum IFO 31855. The enzyme catalyzed the stereoselective reduction of ethyl 4-chloro-3-oxobutanoate to the corresponding (S)-alcohol with a >99% enantiomer excess. The relative molecular mass of the enzyme was estimated to be 68,000 by gel filtration chromatography and 24,800 on SDS polyacrylamide gel electrophoresis. The enzyme had an extremely narrow substrate specificity and it highly reduced conjugated diketone, 2,3-butanedion, in addition to ethyl 4-chloro-3-oxobutanoate. The enzyme activity was inhibited by HgCl2 (100%), 5,5′-dithiobis(2-nitrobenzoic acid) (56%), dicoumarol (42%), and CuSO4 (46%). The N-terminal amino acid sequence of the enzyme (P-Q-G-I-P-T-A-S-R-L) showed no apparent similarity with those of other oxidoreductases.

Stimulatory Effect of Acetate and Propionate on Aspergillic Acid Formation by Aspergillus oryzae A 21

Abstract The stimulatory effect of acetate and propionate on the formation of aspergillic acid (AA) by Aspergillus oryzae A 21 was investigated. 14C labeled AA with a high specific activity was biosynthesized from [2-14C]propionate or [1-14C]acetate in a medium without leucine and isoleucine, precursors in the biosynthesis of AA. Incorporation of three intact acetate units derived from [1,2-13C]acetate into AA via leucine and isoleucine was demonstrated by 13C NMR analyses. Furthermore, a depressive effect of propionate on the catabolism of leucine and isoleucine was assumed to bring about the increase in the formation of AA.

Microbial degradation of aspergillic acid by Trichoderma koningii M 102

Abstract A microorganism, strain M 102, capable of degrading aspergillic acid (AA), was first isolated from a soil sample in a drainage ditch and was identified as Trichoderma koningii Oudemans. This fungus degraded AA, but not hydroxyaspergillic acid (HAA) or deoxyaspergillic acid (DAA). The AA-degrading ability of M 102 was induced by incubation with AA but not with HAA or DAA. AA-degradation activity was found in a crude enzyme prepared from the mycelia induced by AA; this AA degradation reaction required NAD(P)H and oxygen.