Biodegradation of polyethylene by bacterial strains isolated from Kashmir Cave, Buner, Pakistan

Abstract

Low density polyethylene (LDPE) is used for making common shopping bags and plastic sheets and is a significant source of environmental pollution. The present study was aimed at testing the ability of bacterial strains identified as Serratia sp. KC1-MRL, Bacillus licheniformis KC2-MRL, Bacillus sp. KC3-MRL and Stenotrophomonas sp. KC4-MRL isolated from a limestone cave to degrade polyethylene. These strains were isolated from soil of Kashmir Smast, a limestone cave in Buner, Pakistan. These strains showed antibacterial activity against Micrococcus luteus, Klebsiella sp., Pseudomonas sp., and Staphylococcus aureus. The pieces of LDPE plastic were incubated along with bacterial strains for a period of one month and then analyzed. Degradation was observed in terms of growth of microorganisms used in consortia, chemical changes in the composition of LDPE by fourier-transform infrared spectroscopy, and changes in physical structure of LDPE by scanning electron microscopy. Maximum growth (107310 5 CFU mL À1 ) at 28 8C and subsequent change in chemical and physical properties of plastic were observed in the presence of calcium and glucose. The cave soil sample had a very high concentration of calcium. The microscopy showed adherence of bacteria with lots of mechanical damage and erosion on the surface of plastic films incubated with bacterial consortia. The spectroscopy showed breakdown and formation of many compounds, as evident by the appearance and disappearance of peaks in LDPE treated with bacterial consortia as compared to the untreated control. We conclude that antibiotic-producing cave bacteria were able to bring about physical and chemical changes in LDPE pieces and degradation of LDPE was enhanced in media augmented with calcium.

Shotgun metagenomic sequencing from Manao-Pee cave, Thailand, reveals insight into the microbial community structure and its metabolic potential

“…Some of these compounds can be very toxic, but can be transformed into less toxic compounds by various biological pathways [81, 82]. It has been reported that stress or low nutrient habitats can force living microoganisms to use any available nutrients to survive [83]; thus, cave-dwelling microroganisms may use the by-products of xenobiotic biodegradation for energy, nutrients, or final electron acceptors for their growth [79]. For instance, it has been reported that various bacteria ( Serratia sp.…”

“…KC3-MRL, Stenotrophomonas sp. KC4-MRL) isolated from soil samples of Kashmir Smast, a limestone cave in Khyber Pakhtoonkhuwa province, Pakistan, are capable of degrading polyethylene [83]. Therefore, it is also likely that xenobiotic biodegradation and metabolism might be another important process in sustaining diverse groups of microorganisms in Manao-Pee cave.…”

Biodegradation efficacy of soil inherent novel sp. Bacillus tropicus (MK318648) onto low density polyethylene matrix

“…In the present study (Fig. 8 ), the characteristic peak at 2915 cm - 1 , 2928 cm −1 , and 2848 cm −1 indicate the asymmetric and symmetric C-H stretching vibration respectively [ 38 ]. The band at 1470 cm −1 [ 39 ] became remarkably weaker after microbial treatment providing the evidence of the presence of the C = H bond.…”

A Review: Plastics Waste Biodegradation Using Plastics-Degrading Bacteria

“…Furthermore, Jamil et al (49), reported that Serratia sp. KCI-MRL, Bacillus licheniformis KC2-MRL, Bacillus sp.…”

“…KC4-MRL isolated from the soil in Khasmir Smast, Pakistan, were able to damage the surface of LDPE plastic films within one month of incubation. Harshvardhan and Jha, cited from Jamil et al (49) stated that LDPE biodegradation through a series of enzymatic reactions involving various enzymes that catalyze chemical changes of plastic polymers such as oxidation, reduction, hydrolysis, esterification, and molecular inner conversion.…”