Mitsuo Chubachi

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.

Oxidation intermediates of α-glucosyl rutin by pulse radiolysis

Abstract Transient intermediates generated in the reaction of α-glucosyl rutin (G-rutin) with the OH radical or the azide radical were investigated by pulse radiolysis. The OH radical reacted with G-rutin to produce the OH-adduct radical, followed by deprotonation in neutral and acidic solutions. In alkaline solutions, the OH-adduct di-anion radical formed from the di-anions of G-rutin were dehydrated to the phenoxyl radical. On the other hand, G-rutin was oxidized to one-electron oxidized cation radical by the azide radical. The pK a values of the OH radical adduct were found to be 6.83 ± 0.10 and 8.87 ± 0.13. While, the pK a values of the phenoxyl radical of G-rutin were found to be 7.52 ± 0.11 and 9.95 ± 0.13.

Metabolism of n-alkyl-substituted cyclohexanes with an odd number of carbon atoms in the side chain by Micrococcus sp. RCO-4M

The metabolism of n-alkyl-substituted cyclohexanes (n-ACH) with an odd number of carbon atoms (7, 9, 11) in the side chain by Micrococcus sp. RCO-4M was investigated. Evidence for the formation of cyclohexanecarboxylic acid (C6CA), 1-cyclohexenecarboxylic acid (1-ene-C6CA), and trans-4-hydroxycyclohexanecarboxylic acid (t-4-OH-C6CA) is presented. A large amount of C6CA, 1-ene-C6CA and the small quantity of t-4-OH-C6CA were accumulated in culture broth. It is suggested that Micrococcus sp. RCO-4M metabolized n-ACH with an odd number of carbon atoms in the side chain to C6CA by beta-oxidation of the side chain and furthermore degraded C6CA by two pathways involving 1-ene-C6CA and t-4-OH-C6CA as key intermediates.

Identification of the degradation products of aspergillic acid by Trichoderma koningii M 102

Abstract Isolation and identification of the degradation products of aspergillic acid, a secondary metabolite of fungi, by Trichoderma koningii M 102 were undertaken. 14 C-labeling experiments indicated that aspergillic acid was broken-down to a water-soluble degradation product and a chloroform-soluble one. Consequently, leucine and a new microbial metabolite, 2-hydroxyimino-3-methyl-1-pentanol, were isolated and identified as the degradation products formed by cleavage of the pyrazine ring of aspergillic acid by T. koningii M 102.