Bioplastic (poly-3-hydroxybutyrate) production by the marine bacterium Pseudodonghicola xiamenensis through date syrup valorization and structural assessment of the biopolymer

Abstract

Biobased degradable plastics have received significant attention owing to their potential application as a green alternative to synthetic plastics. A dye-based procedure was used to screen poly-3hydroxybutyrate (PHB)-producing marine bacteria isolated from the Red Sea, Saudi Arabia. Among the 56 bacterial isolates, Pseudodonghicola xiamenensis, identified using 16S rRNA gene analyses, accumulated the highest amount of PHB. The highest PHB production by P. xiamenensis was achieved after 96 h of incubation at pH 7.5 and 35 °C in the presence of 4% NaCl, and peptone was the preferred nitrogen source. The use of date syrup at 4% (w/v) resulted in a PHB concentration of 15.54 g/L and a PHB yield of 38.85% of the date syrup, with a productivity rate of 0.162 g/L/h, which could substantially improve the production cost. Structural assessment of the bioplastic by Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy revealed the presence of methyl, hydroxyl, methine, methylene, and ester carbonyl groups in the extracted polymer. The derivative products of butanoic acid estimated by gas chromatography-mass spectrometry [butanoic acid, 2-amino-4-(methylseleno), hexanoic acid, 4-methyl-, methyl ester, and hexanedioic acid, monomethyl ester] confirmed the structure of PHB. The present results are the first report on the production of a bioplastic by P. xiamenensis, suggesting that Red Sea habitats are a potential biological reservoir for novel bioplastic-producing bacteria. Petroleum-based plastic has been rapidly produced in recent decades, and its biodegradation resistance has led to a serious environmental issue for the management of solid wastes 1. The global demand for bioplastic as a substitute for synthetic plastics has increased due to its nontoxicity, renewability, biocompatibility, and biodegradability 2. Degradable biobased plastics can be produced from different renewable raw materials (polysaccharides and proteins), plants (starch-based plastics and cellulose-based plastics), and microbial bioplastics (polylactic acid and polyhydroxyalkanoates (PHAs)) 3. PHAs are the most promising type of bioplastic; they are nontoxic, biodegradable and biocompatible and have properties similar to those of conventional plastics 4. PHAs are biopolymers with diverse structures; as a defense mechanism for surviving stress conditions with nutrient imbalance, PHAs accumulate inside bacterial cells as stored energy 5. The considerable variations in functional groups from methyl to tridecyl, unsaturated bonds, and chain length make PHAs appropriate biopolymers for many different applications 6. The most common form of PHAs is poly-3-hydroxybutyrate (PHB), which accumulates in many microbes by binding β-hydroxybutyrate monomers with ester bonds 7. The universal manufacturing capacity of

Bioplastic from Renewable Biomass: A Facile Solution for a Greener Environment

“…The most common PHA is polyhydroxybutyrate (PHB), produced from low-cost sugarcane molasses by Bacillus cereus (Suryawanshi et al 2020) or Staphylococcus epidermidis (Sarkar et al 2014), cheap agro-residues by Bacillus sp. (Getachew and Woldesenbet 2016), date syrup by Pseudodonghicola xiamenensis (Mostafa et al 2020), non-food sugars from oil palm frond (Zahari et al 2015) or biodiesel industry by-products (García 2013) or used cooking oil (Martino 2014) by Cupriavidus necator, wheat straw lignocellulosic hydrolysates by Burkholderia sacchari (Cesário et al 2014), wheat bran hydrolysate by Ralstonia eutropha (Annamalai and Sivakumar 2016), bakery waste hydrolysate by Halomonas boliviensis (Pleissner 2014). An innovative approach consists of PHB production from landfill methane by methanotrophs (Chidambarampadmavathy et al 2017).…”

Co-production of biopolymers and quinone via no-sugar fermentation--a case by Methylobacterium sp. XJLM

“…Nowadays, along with the increasing demands for polymer plastics, which can be widely used from product packing and daily tools to equipment parts and construction sectors, the growing serious petroleum-based plastic pollution has drawn more attractive attentions due to its less biodegradation property (Cardoso et al 2020;Mostafa et al 2020). In order to solve this global circumstance, many scientists have put great efforts on biodegradable polymers production.…”

“…In order to solve this global circumstance, many scientists have put great efforts on biodegradable polymers production. For showing similar thermoplastic, elastomeric and other physical-chemical properties to conventional plastics, polydroxyalkanoates (PHAs) are regarded as the most potential substituent, which can be completely degraded to CO 2 and H 2 O (Sukruansuwan 2018;Mostafa et al 2020). However, the high cost of PHAs production from costly substrates has seriously limited the utilization of PHAs in commercial elds, which forces scientists to explore alternative approaches to produce it at a lower price (Parveez et al 2015).…”

Microbes and plastic waste management

“…The species of Bacillus, Alcaligenes and Pseudomonas, accumulate PHB up to 90% of cell dry weight under nutrients limited conditions (Prabisha et al 2015). Recently, Pseudodonghicola xiamenensis, an isolate from Red Sea, has been reported for PHB production (Mostafa et al 2020).…”

“…Wastes from other types of industries such as pulp, paper and cardboard industry, wastewater, waste rapeseed oil, waste palm oil, oil extracted from the spent coffee grounds, wastewater from yeast industry and domestic waste water have also been explored for PHB production (Bhuwal et al 2013;Cruz et al 2014;Nogueira et al 2018;Ozdemir and Ceyhan 2011;Verlinden et al 2011). Recently, PHB production by Pseudodonghicola xiaminensis, is reported by using date syrup as a substrate (Mostafa et al 2020). These studies support that agriculture wastes have the potential to be used as a substrate to generate PHB at a much lower cost than by using refined sugar sources.…”