Environmental challenges

- The electrical conductivity increased with the increase in incubation period. - The pH of solutions decreased from 5 to 4.11 after 10 days under 7 °C, to 4.76 after 20 days under 23 °C, and to 4.77 after 20 days under 37 °C and 44 °C. - The biodegradation process is strongly influenced by environmental conditions. - This degradation leads to the cells growth in the medium. - The effects of an acidic pH condition seems to be counterbalanced by low environmental temperatures. The main problem about plastic packaging after their use is the fate of the plastic waste disposed of into the environment. This study was carried out in aquatic microcosm and aimed at assessing the impact of the temperature of an acidic environment on the polyethylene degradation by the bacterium Pseudomonas aeruginosa , as well as the electrical conductivity of the medium and the temporal abundance dynamics of cells involved. Sterilized pieces of polyethylene of 0.08 g in weight were immersed in sterile mineral solutions of pH 5 in glass flasks containing P. aeruginosa cells at concentration adjusted to 186.10 3 CFU/100 µL. The whole was incubated at 7 °C, 23 °C, 37 °C and 44 °C for 10 days, 20 days and 30 days. Analysis after incubations showed that electrical conductivity which was 3386 µS/cm at the initial moment increased with an increase in incubation period. Its highest value 5476 µS/cm was noted at 44 °C after 30 days. The pH of solutions decreased. Its lowest value 4.11 was noted at 7 °C after 10 and 20 days. The apparent degradation rates of polyethylene fragments varied from 8.10 −5 g/10days (at 7 °C and 23 °C) to 2.10 −4 g/10days (at 44 °C). The highest percentage of weight loss of the polyethylene was 6.25% registered after 30 days at 44 °C. The apparent changing rates in cell abundance varied with variation in incubation temperature. It was positive under 7 °C and 23 °C reflecting relative cell growth, and negative under 37 °C and 44 °C reflecting relative cell inhibition. The highest relative apparent cell growth rate was 1.8...

Biodegradation of polyethylene by the bacterium Pseudomonas aeruginosa in acidic aquatic microcosm and effect of the environmental temperature