Bioprospecting and Molecular Identification of Used Transformer Oil-Degrading Bacteria for Bioplastics Production

Shehu Idris,Rashidah Abdul Rahim,Al-Ashraf Abdullah Amirul

doi:10.3390/microorganisms10030583

Shehu Idris, Rashidah Abdul Rahim + Show 1 more

Open Access

https://doi.org/10.3390/microorganisms10030583

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Abstract

One of the major impediments to the commercialization of biodegradable plastic is the high cost of substrate. Consequently, there is a continuous search for effective microorganisms and cheaper carbon substrates to reduce the high production cost. In this study, waste transformer oil-degrading bacteria were isolated from soil, wastewater, and sediment samples, using a mineral salt medium (MSM) supplemented with 1% waste transformer oil as the sole carbon source. The isolates were screened for polyhydroxyalkanoates (PHA) production using Nile red staining and fluorescence microscopy. PHA granules accumulation was confirmed using transmission electron microscopy. Oil degradation analysis was accomplished using solvent extraction and gravimetric methods whereas, the bacteria were identified using 16S DNA sequence homology. A total of 62 transformer oil-degrading bacteria were isolated, out of which 16 (26%) showed positive results for Nile red fluorescence microscopy. The identified organisms belong to four different taxonomic genera of Acinetobacter, Bacillus, Proteus, and Serratia. The percentage of oil degradation observed among the different isolates ranged between 19.58% and 57.51%. Analysis of the PHA extracted from the selected isolate revealed the presence of medium chain length polyhydroxyalkanoates (mcl-PHA). The findings of this work have further highlighted the diversity of the bacteria capable of utilizing waste streams such as waste transformer oil. Consequently, the isolates can be explored as agents of converting waste transformer oil into bioplastics.

Highlights

The isolates can be explored as agents of converting waste transformer oil into bioplastics
We described the isolation and screening of PHAproducing strains of the waste transformer oil-degrading bacteria to target the utilization of such organisms in the bioconversion of used transformer oil (UTO) into biodegradable plastics
The sample of used transformer oil was obtained from Tenaga National Berhad Research (TNBR) Malaysia

Summary

Introduction

Synthetic plastics have become an important commodity considered to have improved the quality of human life, replacing packaging materials like glasses and paper [1]. Rapid development in material science and technology has undoubtedly brought about new plastic products with excellent mechanical integrity as well as durability [2]. The production of synthetic plastics has a great disadvantage of creating non-degradable waste products that are difficult to handle. The non-biodegradable property of these products, high molecular mass and complex structure, impart a serious environmental problem as they can persist in the soil, water bodies, and landfills. The current situation of waste plastics management in developed nations, though slowly improving, is far from satisfactory. As for the developing countries, such waste management can be described as less promising [3]. Several researchers across the globe have been trying to provide a solution to this ever-increasing environmental challenge

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