title: Protease cell wall degradation of Chlorella vulgaris: effect on methane production.
abstract: In order to optimize the enzymatic dosage and microalgae biomass loads subjected to enzymatic hydrolysis prior anaerobic digestion of Chlorella vulgaris, organic matter solubilisation and methane production were investigated. Experimental data using protease dosage of 0.585 AU g DW(-1) showed that increasing biomass loads up to 65 g L(-1) did not affect markedly the hydrolysis efficiency (51%). Enzymatically pretreated biomasses subjected to anaerobic digestion enhanced methane production by 50-70%. The attempt of decreasing the enzymatic dosages revealed diminished hydrolysis efficiency concomitantly with a decreased methane production enhancement. In agreement with the good results observed for organic matter conversion into biogas, total nitrogen mineralization was attained for enzymatically pretreated biomass. Despite the high protein content of the biomass and the biocatalyst used in the present study no ammonia inhibition was detected.
authors.affiliation: Biotechnological Processes for Energy Production Unit - IMDEA Energy, 28935 Móstoles, Madrid, Spain; Department of Agricultural Microbiology, Faculty of Agriculture, Zagazig University, 44511 Zagazig, Egypt.
authors.forename: Ahmed
authors.initials: A
authors.lastname: Mahdy
authors.affiliation: Biotechnological Processes for Energy Production Unit - IMDEA Energy, 28935 Móstoles, Madrid, Spain.
authors.forename: Lara
authors.initials: L
authors.lastname: Mendez
authors.affiliation: Department of Biodiversity and Environmental Management, University of León, 24071 León, Spain.
authors.forename: Saul
authors.initials: S
authors.lastname: Blanco
authors.affiliation: Biotechnological Processes for Energy Production Unit - IMDEA Energy, 28935 Móstoles, Madrid, Spain; Biofuels Unit - Research Center for Energy, Environment and Technology (CIEMAT), 28040 Madrid, Spain.
authors.forename: Mercedes
authors.initials: M
authors.lastname: Ballesteros
authors.affiliation: Biotechnological Processes for Energy Production Unit - IMDEA Energy, 28935 Móstoles, Madrid, Spain. Electronic address: cristina.gonzalez@imdea.org.
authors.forename: Cristina
authors.initials: C
authors.lastname: González-Fernández
mesh_terms: D057919:Biological Oxygen Demand Analysis; D018533:Biomass; D002384:Catalysis; D002473:Cell Wall / Q000378:metabolism*; D048408:Chlorella vulgaris / Q000378:metabolism*; D002849:Chromatography, Gas; D006868:Hydrolysis; D008697:Methane / Q000096:biosynthesis*; D009584:Nitrogen / Q000378:metabolism; D010447:Peptide Hydrolases / Q000378:metabolism*; D013381:Subtilisins; D014865:Waste Disposal, Fluid / Q000379:methods*
chemical_list: D010447:Peptide Hydrolases; D013381:Subtilisins; D009584:Nitrogen; D008697:Methane
keywords: Biomass loads; Chlorella vulgaris; Enzymatic dosage; Methane production; Protease