The TOL catabolic plasmid was shown to be compatible with the R91 drug resistance plasmid. However, the TOL plasmid was extremely unstable in mutant PA03 of P. aeruginosa. By selecting for stabilization of the TOL plasmid in PA03 harbouring R91, it was possible to isolate a strain in which markers from both R91 and TOL appeared to exist in a single recombinant plasmid. This plasmid, pND3, encoded resistance to carbenicillin, was able to transfer at the same frequency as the R91 plasmid and encoded the ability to grow on m-toluate, p-toluate, m-xylene, p-xylene and toluene. In addition, it was shown to be incompatible with the NAH catabolic plasmid and it could be transferred by transduction. The TOL plasmid could stabilize in PA03 harbouring R91 without fusion with R91, and could stabilize in PA03 in the absence of R91. PA03 harbouring either the recombinant plasmid or the stable TOL plasmid in the absence of R91 could promote bacterial chromosome transfer between mutant derivatives of P. aeruginosa strain P AO.

A Cellulomonas strain (CSI-I) which could readily degrade cotton wool was isolated from soil. Production of cell-bound and extracellular carboxymethylcellulase (CMCase), P-glucosidase and avicelase during growth on different substrates was determined. Methods for the isolation of mutants were assessed and mutants were isolated which were altered in their ability to degrade cotton wool when compared to CSI-L Studies on one mutant (CSl-7) which was able to degrade cotton wool more rapidly than the parent revealed large differences in the levels of cell-bound and extracellular CMCase when compared to CSI-L

Two types of mutants which displayed altered regulation of the NAH catabolic plasmid-encoded catechol meta-cleavage pathway were isolated in Pseudomonas putida. Altered metabolic control was indicated by assay of catechol 2,3-dioxygenase. In one type of mutant the catechol 2,3-dioxygenase was synthesized constitutively. In the other type the range of carbon sources which induce the catechol 2,3-dioxygenase was increased.

Probiotics are mono or mixed cultures of live microorganisms which, when applied to man or animal, beneficially affect the host by improving the properties of the indigenous microflora. Some of the beneficial effects that a probiotic culture can have on its host include improved digestion and absorption of various nutrients (e.g. lactose, starch), production of vitamins and growth factors, protection against pathogens, stimulation of the immune response, reduction of cholesterol levels and reduction of diarrhoea.