Convective drying is a cost saving presewtion technique for the production of bulk products. However, heat senstive bioprodusts may be damaged by convective drying. This paper presents the conception of a convective laboratory dryer with particular features for a simple and rapid examnination of deterioration processes during the drying of biomaterials. The drayer is described and results are given concerning the preservation of microorganisms for environmental applications. The results show that deterioration of the gram-negative bacteria Pseodomonas putida during drying is mainly caused by dehydration. Membrane damage is one of the dehydration deterioration mechanisms. Drying temperatures below 40°C ensure that thermal death of P. putida is neglegible.