oral gavage 10 8 cfu in pbs and 3 and 7 days t later the stools were cultured for the presence of all native bacteroides sp and the recombinant b ovatus using selective culture conditions and use of antibiotics bacteria colonies cfu were quantitated after 24 h the results show that recombinant b ovatus strain colonises the colon of the majority 4 5 of mice for up to one week after a single dose of bacteria the presence of the recombinant b ovatus has no discernable impact on the size of the endogenous populations of bacteroides fig5 shows the construct map of b ovatus expressing either human tgf u03b2 or kgf recombinant strains of b ovatus expressing genes encoding either human kgf bohukgf or tgf u03b2 bohutgf or control strains bobts that contain no heterologous genes were cultured in complete media alone media or in media containing xylan for 8 or 24 h prior to assaying culture supernatants for tgf u03b2 and kgf by elisa some cultures of recombinant b ovatus were cultured with xylan for 8 h prior to removing media and culturing for a further 24 h in complete media alone bohukgf tgf u00b1 xylan fig6 a shows the graphs of the average amounts u00b1 sem of cytokine present in the culture supernatants detected in 3 independent experiments with b ovatus expressing the gene encoding human kgf tgf u03b2 bohutgf fig6 b shows the same experimental data from b ovatus expressing the gene encoding human kfg bohukgf in summary the ability to engineer commensal bacteria to produce immunomodulatory molecules under the control of dietary factors as hereinbefore described offers the potential.