The enzyme profile of methanol-grown Methylophilus methylotrophus has been determined. It shows that the organism uses a variant of the ribulose monophosphate cycle of formaldehyde fixation that involves cleavage of hexose phosphate by 2-keto-3-deoxy-6-phosphogluconate aldolase and a rearrangement sequence involving transketolase and transaldolase. The organism possesses high concentrations of a glucose-6-phosphate dehydrogenase active with both NADP+ and NAD+, and two separate 6-phosphogluconate dehydrogenases, one active with both NADP and NAD+ and the other active only with NAD+. In addition, the organism contains methanol dehydrogenase, and NAD+-linked formaldehyde and formate dehydrogenases, thus possessing the enzymic potential necessary for both cyclic and linear sequences for oxidation of the formaldehyde derived from methanol. Hexulose phosphate synthase, phosphohexuloisomerase, glucose-6-phosphate dehydrogenase and the two 6phosphogluconate dehydrogenases have been purified, characterized and examined for possible regulatory properties.

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Cyanide detoxification was studied by immobilisation of fungal mycelia that had been induced to form cyanide hydratase (formamide hydrolyase) which is able to hydrolyse cyanide to formamide. The fungal pathogens of cyanogenic plants, Stemphylium loti, Gloeocercospora sorghi and Fusarium moniliforme were immobilised using polyelectrolyte flocculating agents. The effect of immobilisation on the enzymic properties of S. loti and G. sorghi were investigated. The apparent Km values increased from 21.0 mmol and 25.5 mmol KCN to 43.5 mmol and 71.0 mmol KCN, respectively. The pH profile for the two enzymes widened on immobilisation. The stoichiometry of 1:1 cyanide utilisation to formamide formation was retained on immobilisation, with complete conversion of 70 mmol KCN in 120 min by 0.12 g dry wt of S. loti and in 6 min by 0.13 g dry wt of G. sorghi. When the two fungi were stabilised by immobilisation, and tested in column reactors containing 1.2 g dry wt of S. loti and 1.3 g dry wt of G. sorghi, they completely converted cyanide (70 mmol; added continuously at 7.5 ml h−1) into formamide for 2 days and 30 days, respectively. Stability was enhanced by inclusion of 1.0 mmol glucose in the 70 mmol KCN solution, by a further 10 h for S. loti and an extra 10 days for G. sorghi. Operational stabilities of immobilised G. sorghi (1.3 g dry wt) and F. moniliforme (1.0 g wet wt) in column reactors, with 100 % cyanide conversion, at varying flow rates was investigated. G. sorghi was stable for 15, 10 and 2 days whereas F. moniliforme was only stable for 48, 20 and 10 h at 30, 60 and 120 ml h−1 flow rates respectively.