Cellulose-functionalized magnetic nanoparticle-mediated isolation of novel cellulolytic bacteria

The cellulolytic bacteria are crucial for applications in animal feeds, food processing, and bioenergy production. However, isolation of these bacteria from the microbial community has been challenging due to limitations in current methodologies. This study introduces a novel cellulose-functionalized magnetic nanoparticle-mediated isolation technique designed to enhance the recovery of cellulolytic bacteria. We hypothesized that bacteria could adhere to magnetic nanoparticles coated with cellulose, allowing selective isolation of cellulolytic strains through their cellulase activity-induced magnetic loss. The magnetic nanocomposite was synthesized and functionalized with cellulose (magnetic nanoparticle-cellulose composite [MNPC]). The anaerobic <i>Streptococcus bovis</i> was used to evaluate the bacteria capture efficiency of MNPCs. A mixture of <i>Cellulomonas flavigena</i> (a cellulolytic bacterium) and <i>S. bovis</i> (a non-cellulolytic bacterium) was used to evaluate the cellulolytic bacteria isolation specificity of the method. This method was also applied to isolate the novel ruminal cellulolytic bacteria. The results showed that the magnetic nanoparticle had an average size of 20.00 nm and superparamagnetism. MNPC achieved a bacterial capture efficiency of 99% and a high specificity. The method successfully captured the known cellulolytic bacteria from the rumen of cattle, including <i>Fibrobacter</i>, <i>Ruminococcus flavefaciens</i>, and <i>Butyrivibrio</i>, indicating its reliability. Furthermore, a novel cellulolytic species from the family <i>Lachnospiraceae</i> was isolated from the rumen, with genome analysis revealing cellulolytic pathway genes encoding endoglucanase, β-glucosidase, and cellobiose phosphorylase. In conclusion, the cellulose-functionalized magnetic nanoparticle-mediated isolation method presents a promising approach for the efficient enrichment and isolation of active cellulolytic bacteria. This technique and the isolated strains have potential applications in enhancing animal productivity, bioenergy production, and the food industry.IMPORTANCELignocellulosic biomass, as the primary component of cell walls in gramineous plants, is widely recognized as an ideal biofuel feedstock due to its sustainability and renewability. It can be digested and degraded by cellulolytic microorganisms, converting it into absorbable proteins and volatile fatty acids that provide energy for the organism. However, isolation of these bacteria from the microbial community has been challenging due to the limitations in current methodologies. In this work, we developed a new method, the cellulose-functionalized magnetic nanoparticle-mediated isolation technology, which can contribute to capture highly active cellulolytic bacteria. We isolated a novel unclassified cellulolytic strain of the <i>Lachnospiraceae</i> from the rumen of cattle. This methodology presents a promising approach for the efficient enrichment and isolation of active cellulolytic bacteria from the community.