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Abstract. Bacteria and microalgae in the aquatic environment interact in various ways. Some bacteria have the potential to accelerate microalgae growth. Amylolytic and cellulolytic bacteria which living in freshwater environments (lakes) can decompose complex compounds into simpler ones that needed by microalgae. However, there is limited information about amylolytic and cellulolytic bacteria in Ranu Pani, Ranu Regulo, Ranu Grati and Lake Ngebel. This study aims to examine the potential of amylolytic and cellulolytic bacteria isolated from Ranu Pani, Ranu Regulo, Ranu Grati and Lake Ngebel. The amylolytic test was performed through planted the bacterial isolates from each lake on Amilum agar. Meanwhile, the cellulolytic test was performed using CMC (Carboxymethyl cellulose) media. Our recent finding from 4 lakes showed that 53 isolates had the potential to hydrolyze starch, and 47 isolates had the potential to hydrolyze cellulose. The ANOVA results showed there were differences significantly (p<0.050) in the hydrolysis ability of amylolytic and cellulolytic bacteria isolates. The bacteria with the highest amylum hydrolysis ability were PAS isolates with hydrolysis index 5.89. The bacteria with the highest cellulose hydrolysis ability were PSS isolates with hydrolysis index 6.912. Based on the analysis of 16S rRNA gene sequences, PSS isolates were Bacillus paramycoides and PAS isolates were Bacillus subtillis and the two bacterial were isolates from Ranu Pani.