Aims: The effects of plasterboard composition on Streptomyces californicus growth and bioactivity of spores were studied. Methods and Results: Streptomyces californicus was grown on 13 modified plasterboards under saturated humidity conditions. The total content of fatty acid methyl esters was used for quantifying S. californicus biomass, while the spore-induced cytotoxicity and production of nitric oxide (NO), tumour necrosis factor-alpha, and interleukine-6 (IL-6) in mouse macrophages was used to assess the bioactivity of spores. Removal of starch completely from the plasterboard or only from the core reduced significantly the biomass production and the biological activity of spores in comparison with reference board. The biocide added into the core or on the liner decreased the growth markedly and inhibited the sporulation totally. The biomass production correlated positively with the spore number, cytotoxicity, and production of NO and IL-6. Conclusions: Streptomyces californicus grew under nutrient limitation on all studied plasterboards. The starch is the major factor enabling S. californicus to grow and to produce biologically active metabolites on plasterboard. Significance and Impact of the Study: The composition of building material has an impact on microbial growth and bioactivity of spores which may be involved in complex mechanisms leading to respiratory symptoms in the occupants in moisture damaged buildings.