Achromobacter xylosoxidans as a new microorganism strain colonizing high-density polyethylene as a key step to its biodegradation

This study presents results of research on isolation new bacteria strain Achromobacter xylosoxidans able to effect on the structure of high-density polyethylene (HDPE), polymer resistant to degradation in environment. New strain of A. xylosoxidans PE-1 was isolated from the soil and identified by analysis of the 16S ribosome subunit coding sequences. The substance to be degraded was HDPE in the form of thin foil films. The foil samples were analyzed with Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR) as well as scanning electron microscope (SEM), and the results revealed degradation of chemical structure of HDPE. About 9 % loss of weight was also detected as a result of A. xylosoxidans PE-1 effect on HDPE foil. On the basis of comparative spectral analysis of the raw material before the bacteria treatment and the spectrum from a spectra database, it was assumed that the HDPE was the only source of carbon and energy for the microorganisms. No fillers or other additives used in the plastic processing were observed in HDPE before experiments. This is the first communication showing that A. xylosoxidans is able to modify chemical structure of HDPE, what was observed both on FTIR, in mass reduction of HDPE and SEM analysis. We also observed quite good growth of the bacteria also when the HDPE was the sole carbon source in the medium. These results prove that A. xylosoxidans is an organism worth applying in future HDPE biodegradation studies

Bioremediation potential of Lentinus subnudus in decontaminating crude oil polluted soil

The aim of this work was to study the efficacy of using a white-rot fungi Lentinus subnudus to treat crude oil polluted soil by employing its biodegradation and bioaccumulation potentials. The polluted soil was amended  with plantain peels and treated with spawns of Lentinus subnudus for 180 days. The physicochemical  parameters monitored during the study were Total Hydrocarbon Content(THC), Total Nitrogen, Total Organic Carbon, Ash content, Phosphate, Potassium, Nitrate, Organic matter, pH and heavy metals (Fe, Mn, Zn, Cu, Cr, Cd, Pb, Ni and V). The mushroom demonstrated ability to biodegrade hydrocarbon pollutants in the soil as evident by decreased levels of THC which ranged from 20.46% - 91.94%. Results also showed decreased concentrations of all heavy metals analysed. Lentinus subnudus was more efficient in decreasing the levels of Cd, Cr, Pb, Ni and V than Fe, Mn, Cu and Zn. Observed values of Mn and V were 33.5% and 98.16%,  respectively, after 180 days of treatment. This study demonstrated that Lentinus subnudus could be used in bioremediation of crude oil polluted soil amended with plantain peels.Keywords: Biodegradation, bioaccumulation, Lentinus subnudus, plantain peels

Biodegradation of Polyethylene by Bacillus sp. Indigenous to the Niger Delta Mangrove Swamp

The ability of Bacillus mycoides and Bacillus subtilis (Bacillus species indigenous to the Niger Delta mangrove soil) to biodegrade polyethylene was studied. Low-density polyethylene (LDPE) and high-density polyethylene (HDPE) films were exposed outdoor for 24 weeks. The two isolates were able to grow on polyethylene (PE), forming visible biofilms. The plasmid pattern of the Bacillus species showed a similar pattern among the two Bacillus species, with one plasmid number and molecular weight around 25 kb, indicating a mega plasmid. The mean heterotrophic bacterial counts in the mangrove soil ranged between 2.81 x 105 – 3.20 x 108 CFU/g. The rate of degradation was determined by measurement of the residual weight of the PE films. Biodegradation in Erlenmeyer flasks by the bacteria after 60 days of incubation ranged between 8.41%-23.15%. Biodegradation was confirmed by Fourier-Transform Infrared (FTIR) spectroscopy, which showed introduction of carbonyl groups after natural weathering, which decreased after microbial treatment. Decrease in carbonyl index ranged between 10.5%-13.7%. The result showed that certain Bacillus sp. indigenous to the Niger Delta mangrove soil are capable of growing on PE films and biodegrade them, after an initial abiotic degradation.Key words: Bacillus mycoides, Bacillus subtilis, biodegradation, carbonyl index, Natural weathering, Niger Delta mangrove