Biodesulfurisation of DBT with Pseudomonas putida CECT5279 by resting cells: Influence of cell growth time on reducing equivalent concentration and HpaC activity |
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| Institution: | 1. Discipline of Medical Radiation Sciences in the Faculty of Health Sciences and the Brain and Mind Center, The University of Sydney, Australia;2. Sydney Breast Clinic, 97 – 99 Bathurst Street Sydney, NSW, 2000, Australia;3. Department of Radiography and Radiology, University of Calabar, PMB 1115, Calabar, Nigeria;1. Universidad Autónoma del Estado de México, Facultad de Química, Centro Conjunto de Investigación en Química Sustentable UAEM-UNAM, Carretera Toluca-Atlacomulco km 14.5, San Cayetano, Toluca, Mexico;2. Maestría en Ciencia de Materiales de la Facultad de Química, Universidad Autónoma del Estado de México, Paseo Colón Esquina Paseo Tollocan S/N, Toluca Estado de México, C.P. 50000, Mexico;3. Universidad Nacional Autónoma de México, Circuito Exterior S/N, Coyoacán, Cd. Universitaria, Ciudad de México, Mexico;4. Instituto Nacional de Investigaciones Nucleares, Carretera México-Toluca km 36.5, Ocoyoacac, Mexico;1. Facultad de Ciencias Químicas e Ingeniería, Universidad Autónoma de Baja California, Tijuana, BC, Mexico;2. Centro de Nanociencias y Nanotecnología, Universidad Nacional Autónoma de México, C.P 22800 Ensenada, B.C., Mexico;3. Instituto Potosino de Investigación Científica y Tecnológica, División de Materiales Avanzados, San Luis Potosí, SLP, Mexico;4. Centro de Investigación en Materiales Avanzados, hih. Chihuahua, CHIH, Mexico;1. Department of Radiology, School of Medicine, University of Colorado Denver, Aurora, Colorado;2. Department of Biostatistics, Colorado School of Public Health, University of Colorado Denver, Aurora, Colorado;1. Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY, United States;2. Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY, United States;3. Division of Pulmonary, Allergy, Critical Care Medicine, Department of Medicine, Columbia University College of Physicians and Surgeons, New York, NY, United States;4. Division of Pediatric Allergy, Immunology, and Rheumatology, Department of Pediatrics, Columbia University College of Physicians and Surgeons, New York, NY, United States |
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| Abstract: | Dibenzothiophene (DBT) biodesulfurisation (BDS) route using a genetically modified organism, Pseudomonas putida CECT 5279, is studied. Tests of BDS with whole cells and with homogenized cells are carried out by taking samples of the cells during growth. The influence of the growth phases in the evolution of the intermediates of the 4S DBT desulfurising route is shown.Conversions of the five key compounds of the 4S route (DBT, DBTO, DBTO2, HBPS and HBP) are measured. DBT conversion values are maximal with cells obtained after 30 h of growth time. HBP conversion values do not coincide with DBT conversion values, the maximum HBP production is obtained with cells grown for 10 h. A greater intermediate DBTO and DBTO2 accumulation in broth is produced with cells obtained at 5 and 10 h of growth time. Nevertheless, the accumulation in broth of HBPS, another intermediate, is considerably lower than that observed with cells obtained at 23, 30 and 45 h of growth time.Also, the concentration of the reducing equivalents (NADH and FMNH2) and flavin-oxido-reductase activity inside the cells is measured. This showed that the concentration of the reducing equivalents and the activity of the HpaC enzyme in the P. putida cytoplasm do not limit BDS rate.The influence of 4S compound transport across cellular membrane is studied by comparison of results obtained by resting cell assays (whole cells) and with homogenized cells assays (disrupted cells). The results show that there is no accumulation of any compound inside the cells, and that the transport rate across the cellular membrane does not limit the overall biodesulfurisation rate. |
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