Isolation of digested sludge-assimilating fungal strains and their potential applications
Article first published online: 20 JUN 2013
© 2013 The Society for Applied Microbiology
Journal of Applied Microbiology
Volume 115, Issue 3, pages 718–726, September 2013
How to Cite
Fujii, K., Kai, Y., Matsunobu, S., Sato, H. and Mikami, A. (2013), Isolation of digested sludge-assimilating fungal strains and their potential applications. Journal of Applied Microbiology, 115: 718–726. doi: 10.1111/jam.12266
- Issue published online: 14 AUG 2013
- Article first published online: 20 JUN 2013
- Manuscript Accepted: 27 MAY 2013
- Manuscript Revised: 22 MAY 2013
- Manuscript Received: 25 APR 2013
- Japan Society
- digested sludge;
Digested sludge (DS) is a major waste product of anaerobic digestion of sewage sludge and is resistant to biodegradation. In this study, we isolated and characterized DS-assimilating fungi from soil.
Methods and Results
We tried to isolate DS-assimilating strains by enrichment culture using DS as the nutrient source, but microbial growth was not observed in any culture. To eliminate the inhibitory effect of metals in DS on microbial growth, acid-treated DS was subsequently used for enrichment, and eight fungal strains were isolated from the subcultures. At least 10–30% reduction in sludge was observed after 1-week cultivation, and prolonged cultivation led to further sludge reduction. All isolates produced xylanase, chitinase and keratinase. Phylogenetic analysis revealed that the isolates were Penicillium, Fusarium, Chaetomium, Cunninghamella, Neosartorya and Umbelopsis. Some isolates were suggested novel species.
To the best of our knowledge, our study is the first to report the isolation of DS-assimilating strains.
Significance and Impact of the Study
These isolates may be useful for commercial production of microbial enzymes using DS as the substrate. Because xylan, chitin and keratin in sludge–hyphae complexes are considered to be partially depolymerized, this material could also be utilized as a readily available fertilizer.