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A protocol was developed for regeneration of pepper (Capsicum annuum var. Ace) through somatic embryogenesis in liquid media. For embryogenic callus formation, mature zygotic embryo explants were used on basal Murashige and Skoog medium with 9.05 ,uM 2,4-dichlorophenoxyacetic acid and 3% sucrose. Embryogenic callus was transferred to liquid basal Murashige and Skoog medium with 4.52 PM 2,4-dichlorophenoxyacetic acid and 3% sucrose in order to increase the mass of the embryogenic culture. After pretreatment with potassium citrate, cells were placed into embryo initiation medium with 6 g 1-l L-proline and a decreased (10 mM) ammonium concentration. Embryos were matured in 1.89 PM abscisic acid containing half-strength Murashige and Skoog medium and converted into plants both in vivo and in vitro at up to a 97% efficiency.

A novel technique is described for the immobilisation of plant cells. The method is simple and does not require the use of potentially toxic gels for the entrapment process. Liquid-suspended cells of two species, Capsicum frutescens Mill. and Daucus carota L. were found to invade, and were strongly retained in, polyurethane foam particles over a 21 day culture period. The viability of the immobilised cells was high (70-80% were alive after 21 days). On agitation of the loaded foam particles in fresh liquid medium, at least 95% of the cells remained immobilised after 3 or 4 days. Cell immobilisation Secondary metabolite production Cell differentiation Polyurethane foamCapsicum frutescens Mill.Daucus carota L.

Since microorganisms normally co-exist with other species in nature, they have developed complex metabolic and physiological responses as a result of such interspecies interactions. We utilized some of these interactions by introducing heat-killed cells of Bacillus subtilis and Staphylococcus aureus to Streptomyces coelicolor cultures and, as a result, stimulated undecylprodigiosin production. Undecylprodigiosin is not only an antibiotic; it has also been attributed with antitumor activities, but, in a defined medium, pure cultures of S. coelicolor produced only low concentrations. Elicitation with B. subtilis increased the maximum undecylprodigiosin concentration by threefold and S. aureus by fivefold compared with the pure culture of S. coelicolor. Growth and glucose consumption of elicited S. coelicolor, however, remained similar to those observed in the pure culture. Furthermore, another positive outcome of the elicitation with both B. subtilis and S. aureus was the earlier onset of undecylprodigiosin production by 24 h compared with the pure culture of S. coelicolor. This is the first time that such a phenomenon has been seen in 2 L bioreactors. Our work supports the use of biotic elicitation in order to enhance the production of secondary metabolites for industrial-scale applications.

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