Desulphurisation of benzothiophene and dibenzothiophene by actinomycete organisms belonging to the genus Rhodococcus, and related taxa.

Desulphurising enzymes remove the sulphur moiety from an organosulphur molecule leaving the carbon skeleton intact. Two kinds of desulphurisation reaction are recognised. The dibenzothiophene (DBT)-specific pathway desulphurises DBT to inorganic sulphite and 2-hydroxybiphenyl (HBP), and the benzothiophene (BTH)-specific pathway desulphurises BTH to 2-(2'-hydroxyphenyl)ethan 1-al (HPEal) and probably inorganic sulphite. The DBT-desulphurisation pathway was originally identified in Rhodococcus erythropolis strain IGTS8 (ATCC 53968), and the BTH-desulphurisation pathway in Gordonia sp. strain 213E (NCIMB 40816). These organisms do not further metabolise the organic product of desulphurisation. In this article current knowledge of the biochemistry and genetics of the desulphurisation enzymes is reviewed. The need for separate, DBT- and BTH-specific desulphurisation routes is rationalised in terms of the chemical differences between the two compounds. The desulphurisation pathway is compared with other microbial DBT-degrading enzyme systems. Finally some comments are made concerning the application of desulphurisation enzymes for fuel desulphurisation and on the relevance of these enzymes to the ecology of the mycolata (sensu Chun et al, 1996).

The use of root abutments in the support of complete dentures.

A clinical study of the use of root abutments as an aid to the support of complete dentures is presented. This technique offers a realistic alternative for patients who are reluctant to face the loss of their remaining natural teeth and the wearing of complete dentures. The abutments enhance the support and stability of the dentures and appear to slow the rate of alveolar resorption. The clinical procedures are straightforward and can be readily applied in general dental practice.