Degradation of polyester polyurethane by a newly isolated soil bacterium, Bacillus subtilis strain MZA-75

Abstract

A polyurethane (PU) degrading bacterial strain MZA-75 was isolated from soil through enrichment technique. The bacterium was identified through 16S rRNA gene sequencing, the phylogenetic analysis indicated the strain MZA-75 belonged to genus Bacillus having maximum similarity with Bacillus subtilis strain JBE0016. The degradation of PU films by strain MZA-75 in mineral salt medium (MSM) was analyzed by scanning electron microscopy (SEM), fourier transform infra-red spectroscopy (FT-IR) and gel permeation chromatography (GPC). SEM revealed the appearance of widespread cracks on the surface. FTIR spectrum showed decrease in ester functional group. Increase in polydispersity index was observed in GPC, which indicates chain scission as a result of microbial treatment. CO2 evolution and cell growth increased when PU was used as carbon source in MSM in Sturm test. Increase in both cell associated and extracellular esterases was observed in the presence of PU indicated by p-Nitrophenyl acetate (pNPA) hydrolysis assay. Analysis of cell free supernatant by gas chromatography-mass spectrometry (GC-MS) revealed that 1,4-butanediol and adipic acid monomers were produced. Bacillus subtilis strain MZA-75 can degrade the soft segment of polyester polyurethane, unfortunately no information about the fate of hard segment could be obtained. Growth of strain MZA-75 in the presence of these metabolites indicated mineralization of ester hydrolysis products into CO2 and H2O.

New insights into the microbial degradation of polyurethanes

“…59 Later and 1.0 mL Lipase AK (10 mg mL À1 ) in water at 50 C. It was found that mass loss decreased with increasing the PCL so segment content in hydrolytic degradation in PBS. 64) and Bacillus subtilis designated as strain MZA-75, 65 having the potential to reduce PU-related waste burden, were isolated from soil through enrichment. In contrast, in the presence of Lipase AK the mass loss was observed to be increased with increasing the PCL so segment content.…”

Degradation of poly(ε-caprolactone) by a thermophilic bacterium Ralstonia sp. strain MRL-TL isolated from hot spring

“…The methylene chloride was allowed to evaporate slowly by placing the covered petri dishes in desiccator (Shah et al, 2013b). This film (~0.2 mm in thickness) was sterilized using 70% ethanol and exposure to UV radiation for 5 min (UV dosage 10771 J/m 2 ).…”

Isolation and Characterization of Low Density Polyethylene Degrading Bacillus Spp. From Garbage Dump Sites

“…The sampling site has been chosen to increase the probability of finding bacterial isolates capable of degrading polyethylene effectively because due to the absence of other carbon sources in these sites, microbes modify their metabolic pathways and the enzyme system to utilize LDPE as a nutrient. Sixteen bacterial colonies were selected on the basis of cultural characteristics and streaked on LDPE emulsified MSM agar plates followed (Shah et al 2013). From this study, it was clear that the bacteria isolated from plastic waste processing areas are capable of utilizing polyethylene as nutritional sources.…”

“…The bacterial isolates were differentiated through colony morphology, microscopic examination and biochemical test (Shah et al 2013). Morphological characterization of the isolates was done by Gram's staining method (Beveridge, 2001).…”