Exploration of the key microbes involved in the cellulolytic activity of a microbial consortium by serial dilution

► A serial dilution method was successfully employed to explore the key microbes. ► The key functional microbes of a cellulolytic microbial consortium were identified. ► The critical dilution point of this consortium for cellulose degradation was 10−5. ► The key strains belong to Clostridium clariflavum DSM 19732 and Paenibacillus were confirmed.