Comparison of the Biodegradation of Polypropylene (PP) and Low Density Polyethylene (LDPE) by Pseudomonas aeruginosa and Staphylococcus aureus at Different pH Ranges under Mesophilic Condition
Edith Brunelle Mouafo Tamnou
University of Yaounde I, Faculty of Sciences, Laboratory of Hydrobiology and Environment, P.O. Box 812 Yaounde, Cameroon.
Mireille Ebiane Nougang
Zoology Laboratory Department, Faculty of Sciences, University of Maroua, P.O.Box 814 Maroua, Cameroon.
Claire Stéphane Metsopkeng
University of Yaounde I, Faculty of Sciences, Laboratory of Hydrobiology and Environment, P.O. Box 812 Yaounde, Cameroon.
Manouore Njoya Awawou
University of Yaounde I, Faculty of Sciences, Laboratory of Hydrobiology and Environment, P.O. Box 812 Yaounde, Cameroon.
Jean Samuel Eheth
University of Yaounde I, Faculty of Sciences, Laboratory of Hydrobiology and Environment, P.O. Box 812 Yaounde, Cameroon.
Paul Serge Mbenoun Masse
University of Yaounde I, Faculty of Sciences, Laboratory of Zoology, P.O.Box 812 Yaounde, Cameroon.
Paul Alain Nana
Department of Oceanography and Limnology, Institute of Fisheries and Aquatic Sciences, University of Douala, P.O.Box 7236, Douala, Cameroon.
Télesphore Sime-Ngando
Laboratoire Microorganismes Génome et Environnement, UMR CNRS 6023, Université Clermont Auvergne, Campus Universitaire des Cézeaux, 1 Impasse Amélie Murat CS 60026, 63178 Aubière Cedex, France.
Moïse Nola *
University of Yaounde I, Faculty of Sciences, Laboratory of Hydrobiology and Environment, P.O. Box 812 Yaounde, Cameroon.
*Author to whom correspondence should be addressed.
Abstract
The present study aims to assess the temporal variations of some biotic and abiotic biodegradation parameters of 2 polymers (LDPE and PP) by the bacteria P. aeruginosa and S. aureus at acidic, neutral, and alkaline pH under mesophilic conditions. LDPE and PP fragments were immersed in the mineral solutions free of carbon sources containing P. aeruginosa or S. aureus cells. The initial pH values (pHi) of solutions were 5, 7 and 9. Incubation was carried out at 28°C for 10, 20, 30, 40, 50 and 60 days. Results showed that during incubations, the pH of the solutions varies over time. In most cases, the electrical conductivity and cell abundances increased. The weights of the polymers decreased. The cell abundance apparent increasing rates (CAAIR), the electrical conductivity apparent increasing rates (ECAIR), and the polymer weight apparent decreasing rates (PWADR) were estimated. The highest PWADR in the presence of LDPE was 0.4 mg/10days with P. aeruginosaat pHi 5 and 7, and 0.6 mg/10days with S. aureus under pHi 7. For PP, it was constant (0.7 mg/10days) under all pHi with S. aureus, but decreased in the presence of P. aeruginosa with increasing in pHi solutions. The ECAIR with LDPE decreased with increasing pHi with both bacterial species.The highest ECAIR of PP was recorded under pHi 5 with S. aureus and under pHi 7 with P. aeruginosa.The highest CAAIR with LDPE was 185.18 CFU/10days for P. aeruginosa at pHi 5 and 116.79 CFU/10days for S. aureus at pHi 7. With PP, it was 297.61 CFU/10days for P. aeruginosa at pHi 5 and 67.64 CFU/10days for S. aureusat pHi 7. The biodegradation parameters values recorded with of P. aeruginosa differed significantly (P<0.05) from those recorded with S. aureus under each pHi.
Keywords: Biodegradation, bacteria species, initial pH medium, incubation duration, parameters assessment