title: Biodegradation of high concentrations of hexadecane by Aspergillus niger in a solid-state system: kinetic analysis.
abstract: Solid-state microcosms were used to assess the influence of constant and variable C/N ratios on the biodegradation efficiency by Aspergillus niger at high hexadecane (HXD) concentrations (180-717 mg g-1). With a constant C/N ratio, 100% biodegradation (33-44% mineralization) was achieved after 15 days, at rates increasing as the HXD concentration increased. Biomass yields (YX/S) remained almost independent (approximately 0.77) of the carbon-source amount, while the specific growth rates (mu) decreased with increasing concentrations of HXD. With C/N ratios ranging from 29 to 115, complete degradation was only attained at 180 mg g-1, corresponding to 46% mineralization. YX/S diminished (approximately 0.50 units) as the C/N ratio increased. The highest values of mu (1.08 day-1) were obtained at low C/N values. Our results demonstrate that, under balanced nutritional conditions, high HXD concentrations can be completely degraded in solid-state microcosms, with a negligible (<10%) formation of by-products.
authors.affiliation: Centro Nacional de Investigación y Capacitación Ambiental, Instituto Nacional de Ecología, Av. San Rafael Atlixco 186, Col. Vicentina. Iztapalapa, 09340, D.F. Mexico City, Mexico.
authors.forename: Tania
authors.initials: T
authors.lastname: Volke-Sepúlveda
authors.forename: Mariano
authors.initials: M
authors.lastname: Gutiérrez-Rojas
authors.forename: Ernesto
authors.initials: E
authors.lastname: Favela-Torres
mesh_terms: D000473:Alkanes / Q000378:metabolism*; D001234:Aspergillus niger / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D001673:Biodegradation, Environmental; D018533:Biomass; D019149:Bioreactors / Q000382:microbiology; D001709:Biotechnology; D002245:Carbon Dioxide / Q000032:analysis / Q000378:metabolism; D003470:Culture Media / Q000737:chemistry; D005285:Fermentation; D007700:Kinetics; D009584:Nitrogen / Q000032:analysis / Q000378:metabolism; D010101:Oxygen Consumption / Q000187:drug effects; D011140:Polyurethanes / Q000378:metabolism; D011208:Powders / Q000737:chemistry; D013171:Spores, Bacterial / Q000254:growth & development
chemical_list: D000473:Alkanes; D003470:Culture Media; D011140:Polyurethanes; D011208:Powders; D002245:Carbon Dioxide; C007932:n-hexadecane; D009584:Nitrogen