Towards a competitive solid state fermentation : cellulases production from coffee husk by sequential batch operation and role of microbial diversity
Cerda Llanos, Alejandra Patricia (Universitat Autònoma de Barcelona. Departament d'Enginyeria Química, Biològica i Ambiental)
Gea Leiva, Teresa (Universitat Autònoma de Barcelona. Departament d'Enginyeria Química, Biològica i Ambiental)
Vargas-García, Mari Carmen (Universidad de Almería. Unidad de Microbiología)
Sanchez, Antoni (Universitat Autònoma de Barcelona. Departament d'Enginyeria Química, Biològica i Ambiental)

Date:	2017
Abstract:	The cost of cellulases is the main bottleneck for bioethanol production at commercial scale. Solid-state fermentation (SSF) is a promising technology that can potentially reduce cellulases cost by using wastes as substrates. In this work, a SSF system of 4. 5L bioreactors was operated continuously by sequential batch operation using the fermented solids from one batch to inoculate the following batch. Coffee husk was used as lignocellulosic substrate. Compost was used as starter in the first batch to provide a rich microbiota. Two strategies were applied: using 10% fermented solids as inoculum in 48h batches (SB90) and using 50% solids in 24h batches (SB50). A consistent and robust production process was achieved by sequential batch operation. Similar cellulase activities around 10 Filter Paper Units per gram of dry solids were obtained through both strategies. Microbial diversity in the starting materials and in the final fermented solids was characterized by next generation sequencing. Microbial composition of both fermented solids was similar but the relative abundance of families and species was affected by the operation strategy used. Main bacteria in the final solids came from compost (families Sphingobacteriaceae, Paenibacillaceae and Xanthomonadaceae), while main fungi families came from coffee husk (families Phaffomycetaceae, Dipodascaceae and two unidentified families of the class of Tramellomycetes). There was a high presence of non-identified mycobiota in the fermented solids. Main identified species were the bacteria Pseudoxanthonomas taiwanensis (12. 3% in SB50 and 6. 1% in SB90) and Sphingobacterium composti (6. 1% in SB50 and 2. 6% in SB90) and the yeasts Cyberlindnera jardinii and Barnettozyma californica (17. 8 and 4. 1% respectively in SB50 and 34 and 9. 1% in SB90), all four previously described as lignocellulose degraders. The development of these operational strategies and further biological characterization of the end product could eventually benefit the process economics by providing a standard and specialized inoculum for a continuous SSF for cellulases production.
Grants:	Ministerio de Economía y Competitividad CTM2015-69513-R
Rights:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, i la comunicació pública de l'obra, sempre que no sigui amb finalitats comercials, i sempre que es reconegui l'autoria de l'obra original. No es permet la creació d'obres derivades.
Language:	Anglès
Document:	Article ; recerca ; Versió sotmesa a revisió
Subject:	Solid-state fermentation ; Cellulases ; Sequential batch reactor ; Microbial diversity ; Organic wastes
Published in:	Science of the total environment, Vol. 589 (July 2017) , p. 56-65, ISSN 1879-1026

DOI: 10.1016/j.scitotenv.2017.02.184

Preprint 36 p, 909.0 KB

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Research literature > UAB research groups literature > Research Centres and Groups (research output) > Engineering > Composting Research Group (GICOM)
Articles > Research articles
Articles > Published articles