title: Production of microparticles of molinate degrading biocatalysts using the spray drying technique.
abstract: Previous studies demonstrated the capability of mixed culture DC1 to mineralize the thiocarbamate herbicide molinate through the activity of molinate hydrolase (MolA). Because liquid suspensions are not compatible with long-term storage and are not easy to handle when bioremediation strategies are envisaged, in this study spray drying was evaluated as a cost-effective method to store and transport these molinate biocatalysts. Microparticles of mixed culture DC1 (DC1) and of cell free crude extracts containing MolA (MA) were obtained without any carrier polymer, and with calcium alginate (CA) or modified chitosan (MCt) as immobilizing agents. All the DC1 microparticles showed high molinate degrading activity upon storage for 6 months, or after 9 additions of ∼0.4 mM molinate over 1 month. The DC1-MCt microparticles were those with the highest survival rate and lowest heterogeneity. For MA microparticles, only MA-MCt degraded molinate. However, its Vmax was only 1.4% of that of the fresh cell free extract (non spray dried). The feasibility of using the DC1-MCt and MA-MCt microparticles in bioaugmentation processes was assessed in river water microcosms, using mass (g):volume (L) ratios of 1:13 and 1:0.25, respectively. Both type of microparticles removed ∼65-75% of the initial 1.5 mg L(-1) molinate, after 7 days of incubation. However, only DC1-MCt microparticles were able to degrade this environmental concentration of molinate without disturbing the native bacterial community. These results suggest that spray drying can be successfully used to produce DC1-MCt microparticles to remediate molinate polluted sites through a bioaugmentation strategy.
authors.affiliation: LEPABE, Laboratório de Engenharia de Processos, Ambiente, Biotecnologia e Energia, Faculdade de Engenharia, Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal.
authors.forename: Ana R
authors.initials: AR
authors.lastname: Lopes
authors.affiliation: LEPABE, Laboratório de Engenharia de Processos, Ambiente, Biotecnologia e Energia, Faculdade de Engenharia, Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal.
authors.forename: Vera M
authors.initials: VM
authors.lastname: Sousa
authors.affiliation: LEPABE, Laboratório de Engenharia de Processos, Ambiente, Biotecnologia e Energia, Faculdade de Engenharia, Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal.
authors.forename: Berta N
authors.initials: BN
authors.lastname: Estevinho
authors.affiliation: Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Portugal; IBMC, Instituto de Biologia Molecular e Celular da Universidade do Porto, Rua do Campo Alegre, 823, 4150-180 Porto, Portugal.
authors.forename: José P
authors.initials: JP
authors.lastname: Leite
authors.affiliation: LEPABE, Laboratório de Engenharia de Processos, Ambiente, Biotecnologia e Energia, Faculdade de Engenharia, Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal.
authors.forename: Nuno F F
authors.initials: NFF
authors.lastname: Moreira
authors.affiliation: Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Portugal; IBMC, Instituto de Biologia Molecular e Celular da Universidade do Porto, Rua do Campo Alegre, 823, 4150-180 Porto, Portugal; ICBAS - Instituto de Ciências Biomédicas Abel Salazar, Rua de Jorge Viterbo Ferreira n.º 228, 4050-313 Porto, Portugal.
authors.forename: Luís
authors.initials: L
authors.lastname: Gales
authors.affiliation: LEPABE, Laboratório de Engenharia de Processos, Ambiente, Biotecnologia e Energia, Faculdade de Engenharia, Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal.
authors.forename: Fernando
authors.initials: F
authors.lastname: Rocha
authors.affiliation: LEPABE, Laboratório de Engenharia de Processos, Ambiente, Biotecnologia e Energia, Faculdade de Engenharia, Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal. Electronic address: opnunes@fe.up.pt.
authors.forename: Olga C
authors.initials: OC
authors.lastname: Nunes
mesh_terms: D039903:Actinobacteria / Q000201:enzymology / Q000254:growth & development; D001381:Azepines / Q000032:analysis*; D055162:Biocatalysis; D001673:Biodegradation, Environmental; D048271:Chitosan / Q000737:chemistry*; D004339:Drug Compounding; D006540:Herbicides / Q000032:analysis*; D006867:Hydrolases / Q000737:chemistry*; D010316:Particle Size; D000070096:Pseudomonas chlororaphis / Q000201:enzymology / Q000254:growth & development; D020615:Stenotrophomonas maltophilia / Q000201:enzymology / Q000254:growth & development; D013499:Surface Properties; D013859:Thiocarbamates / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis*; D018508:Water Purification / Q000379:methods*
chemical_list: D001381:Azepines; D006540:Herbicides; D013859:Thiocarbamates; D014874:Water Pollutants, Chemical; C009821:molinate; D048271:Chitosan; D006867:Hydrolases
keywords: Bioaugmentation; Calcium alginate; Microparticles; Modified chitosan; Spray-drying