Characterization and Process Optimization for Enhanced Production of Polyhydroxybutyrate (PHB)-Based Biodegradable Polymer from Bacillus flexus Isolated from Municipal Solid Waste Landfill Site

Abstract

In recent years, there has been a growing interest in bio-based degradable plastics as an alternative to synthetic plastic. Polyhyroxybutyrate (PHB) is a macromolecule produced by bacteria as a part of their metabolism. Bacteria accumulate them as reserve materials when growing under different stress conditions. PHBs can be selected as alternatives for the production of biodegradable plastics because of their fast degradation properties when exposed to natural environmental conditions. Hence, the present study was undertaken in order to isolate the potential PHB-producing bacteria isolated from the municipal solid waste landfill site soil samples collected from the Ha’il region of Saudi Arabia to assess the production of PHB using agro-residues as a carbon source and to evaluate the growth of PHB production. In order to screen the isolates for producing PHB, a dye-based procedure was initially employed. Based on the 16S rRNA analysis of the isolates, Bacillus flexus (B. flexus) accumulated the highest amount of PHB of all the isolates. By using a UV–Vis spectrophotometer and Fourier-transform infrared spectrophotometer (FT-IR), in which a sharp absorption band at 1721.93 cm−1 (C=O stretching of ester), 1273.23 cm−1 (–CH group), multiple bands between 1000 and 1300 cm−1 (stretching of the C–O bond), 2939.53 cm−1 (–CH3 stretching), 2880.39 cm−1 (–CH2 stretching) and 3510.02 cm−1 (terminal –OH group), the extracted polymer was characterized and confirmed its structure as PHB. The highest PHB production by B. flexus was obtained after 48 h of incubation (3.9 g/L) at pH 7.0 (3.7 g/L), 35 °C (3.5 g/L) with glucose (4.1 g/L) and peptone (3.4 g/L) as carbon and nitrogen sources, respectively. As a result of the use of various cheap agricultural wastes, such as rice bran, barley bran, wheat bran, orange peel and banana peel as carbon sources, the strain was found to be capable of accumulating PHB. Using response surface methodology (RSM) for optimization of PHB synthesis using a Box–Behnken design (BBD) proved to be highly effective in increasing the polymer yield of the synthesis. With the optimum conditions obtained from RSM, PHB content can be increased by approximately 1.3-fold when compared to an unoptimized medium, resulting in a significant reduction in production costs. Thus, isolate B. flexus is a highly promising candidate for the production of industrial-size quantities of PHB from agricultural wastes and is capable of removing the environmental concerns associated with synthetic plastics from the industrial production process. Moreover, the successful production of bioplastics using a microbial culture provides a promising avenue for the large-scale production of biodegradable and renewable plastics with potential applications in various industries, including packaging, agriculture and medicine.

Identification of prevalent leachate percolation of municipal solid waste landfill: a case study in India

“…The increased heat can cause accelerated degradation, compromising their integrity and performance over time 53 . However, using thermal and biochemical transformations to produce energy-rich substrates and gases for heat and electricity production are also reported 33 , 54 , 55 .…”

“…Leachate sampling was done using grab sampling in 1000 mL bottles made from plastic cleaned thoroughly, and the samples were then stored at 4 °C. The laboratory analyzed various samples using standardized methods outlined in the American Public Health Association’s (APHA) Standard Methods for the Examination of Water and Wastewater 33 . The parameters examined included pH, electrical conductivity, BOD 5 , COD, hardness, alkalinity, total dissolved solid (TDS), chloride, sulphate, nitrate, and iron.…”

A Review on Biofiber-Reinforced Polyhydroxybutyrate (PHB) and Polylactic Acid (PLA) Composites

“…Since the properties of fiber-reinforced composites vary depending on the axis of measurement, they are typically also "orthotropic" mate. Mohd A., Arif J., and colleagues (2023) [76] investigated the characterization and process optimisation for enhanced production of PHB-based biodegradable polymers. PHAs come in a variety of forms, but the most widespread is poly-3-hydroxybutyrate (PHB), an organic substance created by microorganisms by attaching hydroxybutyrate monomers to ester linkages.…”

Unveiling Polyhydroxyalkanoates Producing Bacteria Isolated from Mangalore Environment: An Unearthing Study

“…By 2025, it is expected that there would have been a buildup of 11 billion metric tonnes of plastic in the environment and landfills, causing significant pollutants to infiltrate the ecosystem. (Adnan et al 2023). To prevent this, two alternatives can be considered.…”

“…(Wang et al 2014;Lathwal et al 2015). PHA has quick degrading qualities when exposed to natural environmental conditions hence environment friendly (Adnan et al 2023). PHAs are produced and preserved in the cytoplasm of different bacteria and archaea as water insoluble inclusions (Rehm et al 2003).…”