Cellulolytic potential of bacteria isolated from Australian marsupial herbivores

Cellulose, the most abundant renewable biopolymer on Earth, represents a key resource for biofuel production but requires efficient enzymatic hydrolysis to overcome its structural resistance. In this study, cellulose-degrading bacteria were isolated from fecal samples of two Australian marsupial herbivores: the koala (Phascolarctos cinereus) and the common wombat (Vombatus ursinus). Ten bacterial isolates were screened for cellulolytic activity; four strains exhibited substantial hydrolysis zones on carboxymethyl cellulose (CMC) agar and demonstrated elevated activity in fermentation broth. 16 S rRNA gene sequencing identified three isolates as Streptomyces spp. (K1, KFK6, KFWH) and one as Enterobacter sp. (KFWI). Optimization of cellulase production was conducted by varying incubation periods (24-168 h), pH (3.5-8.5), temperatures (27-50 °C), additives (NaCl, CaCl₂, ZnSO₄, MgSO₄, SDS, EDTA, Tween 80, Triton X-100), carbon sources (glucose, fructose, lactose, sucrose, CMC), and nitrogen sources (yeast extract, ammonium chloride, peptone, urea). K1, KFK6 and KFWI showed maximum CMCase production at 37 °C, whereas KFWH showed maximum production at 40 °C. The optimal pH was 7.5 for K1 and KFWI, and 6.5 for KFK6 and KFWH. Maximum enzyme production occurred at 72 h for K1 and KFWI, 120 h for KFK6, and 96 h for KFWH. These marsupial-derived isolates represent promising candidates for future studies on lignocellulosic biomass hydrolysis and other biotechnological applications.