The paper is dedicated to actual scientific and practical problem solutions for air treatment in microbial pesticide manufacturing. Experimental results of air filtration in series-link filters with 5 μm – 1 μm rating polypropylene cartridges are shown. Obtained microbial contamination level of filtered air 3.4 CFU·m–3 was low and air quality seemed to be sufficient for fermentation broth aeration in the bioreactor. The reasons for such results and prospects of filtration system simplification for pilot-scale microbial pesticide manufacturing are discussed.