Renato Craveri

Stereoselective reduction of non-cyclic carbonyl compounds by some eumycetes

SummaryTwelve strains of Eumycetes were able to perform the reduction of 2-pentanone, acetophenone and ethyl acetoacetate, sometimes in a yield suitable for preparative work. For each substrate, preferential reduction to the R-configurated alcohol was observed with one or more strains.

α-galactosidase from the yeast Candida javanica

Summaryα-Galactosidase (Ec 3.2.1.22) was obtained from the yeast C. javanica grown on a mineral culture medium supplemented with melibiose plus raffinose. The cell-bound α-galactosidase and the preparations from the culture filtrate and from the cells exhibited maximum activity at pH 4 and 70°C. After 15 min at 70°C, 70% of the α-galactosidase activity was recovered, and after 15 min at 80°C complete inactivation was observed. The Michaelis constant (Km) of α-galactosidase on pNPG and on melibiose was about 11 mM. Galactose as a reaction product had no effect on α-galactosidase activity of the preparation from the cells, whereas glucose (2 and 10 mM) increased the activity. On the basis of polyacrylamide gel electrophoresis, the preparation from the cell extract, obtained after ultrafiltration and ethanol precipitation, showed only an active band which stained with Coomassie-blue but not with Schiff-periodate. The α-galactosidase from C. javanica is α-galactosidase A, it lacks invertase and it reduces group B specificity of erythrocytes.

D,L-Carnitine resolution byFusarium oxysporum

SummaryL-Carnitine was obtained in 40% yield from D,L-octanoyl carnitine by enantioselective hydrolysis with a strain ofFusarium oxysporum.

Thermorubin biosynthesis: evidence for the involvement of both salicylic acid and an undecaketide

The mixed biosynthesis of thermorubin, a metabolite produced by a thermophilic actinomycete, from salicylic acid (derived from the shikimate pathway) and an undecaketide is demonstrated.

Ammonium lactate from deproteinized alfalfa juice byStreptococcus faecium

SummaryDeproteinized alfalfa juice is a by-product of the mechanical fractionation of alfalfa to obtain protein. In this work the juice was used as the substrate for the production of ammonium lactate (l-lactic acid) by a strain ofStreptococcus faecium. Batch fermentation with a constant pH of 5.8 gave 27.2 g/l of lactic acid (90% conversion and 1.1 g/l/h productivity) and 6×1012 cells/l after 24 h. Semicontinuous fermentation allowed the conversion of 3-times the volume of deproteinized juice after 44 h, finally giving 29.7 g/l of ammonium lactate (99% conversion and 2.5 g/l/h productivity) and 4–6×1012 cells/l.

Halogenated analogues of mycophenolic acid

Halogenated analogues of mycophenolic acid (I) were produced by cultures of Penicillium brevicompactum fed respectively with 4-bromo-5,7-dihydroxy-phthalide (V) and 4-chloro-5,7-dihydroxyphthalide (VI).