Search

Indiscriminate usage, disposal and recalcitrance of petroleum-based plastics have led to its accumulation leaving a negative impact on the environment. Bioplastics, particularly microbial bioplastics serve as an ecologically sustainable solution to nullify the negative impacts of plastics. Microbial production of biopolymers like Polyhydroxyalkanoates, Polyhydroxybutyrates and Polylactic acid using renewable feedstocks as well as industrial wastes have gained momentum in the recent years. The current study outlays types of bioplastics, their microbial sources and applications in various fields. Scientific evidence on bioplastics has suggested a unique range of applications such as industrial, agricultural and medical applications. Though diverse microorganisms such as Alcaligenes latus, Burkholderia sacchari, Micrococcus species , Lactobacillus pentosus, Bacillus sp., Pseudomonas sp., Klebsiella sp., Rhizobium sp., Enterobacter sp., Escherichia sp., Azototobacter sp., Protomonas sp., Cupriavidus sp., Halomonas sp., Saccharomyces sp., Kluyveromyces sp., and Ralstonia sp. are known to produce bioplastics, the industrial production of bioplastics is still challenging. Thus this paper also provides deep insights on the advancements made to maximise production of bioplastics using different approaches such as metabolic engineering, rDNA technologies and multitude of cultivation strategies. Finally, the constraints to microbial bioplastic production and the future directions of research are briefed. Hence the present review emphasizes on the importance of using bioplastics as a sustainable alternative to petroleum based plastic products to diminish environmental pollution. [Display omitted] • Overview of microbial bioplastics. • Leads and hurdles of microbial bioplastics were discussed. • Diverse applications were discussed. [ABSTRACT FROM AUTHOR]

The rising plastic pollution deteriorates the environment significantly as these petroleum-based plastics are not biodegradable, and their production requires natural fuels (energy source) and other resources. Polyhydroxyalkanoates (PHAs) are bioplastic and a sustainable and eco-friendly alternative to synthetic plastics. PHAs can be entirely synthesized using various microorganisms such as bacteria, algae, and fungi. These value-added biopolymers show promising properties such as enhanced biodegradability, biocompatibility, and other chemo-mechanical properties. Further, it has been established that the properties of PHA polymers depend on the substrates and chemical composition (monomer unit) of these polymers. PHAs hold great potential as an alternative to petroleum-based polymers, and further research for economic production and utilization of these biopolymers is required. The review describes the synthesis mechanism and different properties of microbially synthesized PHAs for various applications. The classification of PHAs and the multiple techniques necessary for their detection and evaluation have been discussed. In addition, the synthesis mechanism involving the genetic regulation of these biopolymers in various microbial groups has been described. This review provides information on various commercially available PHAs and their application in multiple sectors. The industrial production of these microbially synthesized polymers and the different extraction methods have been reviewed in detail. Furthermore, the review provides an insight into the potential applications of this biopolymer in environmental, industrial, and biomedical applications. [Display omitted] • PHA is intracellularly accumulated molecules in microbial cells. • Chemo-mechanical properties of biocompatible PHA resemble synthetic plastics. • phaCAB operon is responsible for the synthesis of PHA. • PHAs are widely used in the industrial, environmental and biomedical sectors. [ABSTRACT FROM AUTHOR]

The craving for an alternative to the existing plastic products gives rise to the concept of algae-based bioplastic production, which appears to be excellently biodegradable and cost-effective. The significant assortment of algal biopolymers draws great attention to stop the surge of plastic waste and to mitigate the burning problems of environmental pollution. The polyhydroxyalkanoates (PHA) are naturally-occurring biopolymers found in the form of esters accumulated within a number of microbes, which provides the pillar for several biomolecules. This review summarizes the global scenario as well as the precise technique of algae-based PHA extraction and bioplastic production. In addition, different techniques for valorisation of PHA production, its biodegradability and its commercial applications are also taken into consideration. [Display omitted] • An extensive literature survey of algal bioproducts. • Extraction and characterization of algal biopolymer resultant chemicals and bioplastics. • Productivity strategy and scale up of bioproducts from microalgae. [ABSTRACT FROM AUTHOR]

The progressive increase of slaughterhouse waste production requires actions for both addressing an environmental issue and creating additional value within a biorefinery concept. In this regard, some of these animal by-products exhibit a significant content of fatty acids that could be efficiently converted into bioplastics such as polyhydroxyalkanoates (PHAs) by adequately performing substrate screening with producing bacterial strains and applying affordable pretreatments. One of the main challenges also relies on the difficulty to emulsify these fat-rich substrates within culture broth and make the fatty acids accessible for the producing bacteria. In this work, the potential of two fat-rich animal by-products, grease trap waste (GTW) and tallow-based jelly (TBJ), as inexpensive carbon sources for microbial growth and PHA production was evaluated for the first time. Upon substrate screening, using different pseudomonadal strains (P. resinovorans , P. putida GPo1, P. putida KT2440) and pretreatment conditions (autoclave-based, thermally-treated or saponified substrates), the highest growth and mcl-PHA production performance was obtained for P. resinovorans , thus producing up to 47% w/w mcl-PHA simply using hygienized GTW. The novel bioprocess described in this study was successfully scaled up to 5 and 15 L, resulting in CDW concentrations of 5.9–12.8 g L−1, mcl-PHA contents of 33–62% w/w and PHA yields of 0.1–0.4 gPHA g−1 fatty acids , greatly depending on the substrate dosing strategy used and depending on culture conditions. Moreover, process robustness was confirmed along Test Series by the roughly stable monomeric composition of the biopolymer produced, mainly formed by 3-hydroxyoctanoate and 3-hydroxydecanoate. The research here conducted is crucial for the cost-effectiveness of mcl-PHA production along this new slaughterhouse waste-based biorefinery concept. [Display omitted] • First report on GTW and TBJ use for microbial growth and PHA production. • Pseudomonas resinovorans remarkably produced mcl-PHA using GTW as sole carbon source. • GTW-based process robustness confirmed by stable polymer composition. • Larger-scale validation led to high PHA yields and contents at multiple GTW dosing. [ABSTRACT FROM AUTHOR]

Apple pomace, the residue which is left out after processing of apple serves as a potential carbon source for the production of biopolymer, PHA (poly-hydroxyalkanoates). It is rich in carbohydrates, fibers and polyphenols. Utilization of these waste resources has dual societal benefit-waste management and conversion of waste to an eco-friendly biopolymer. This will lower the overall economics of the process. A major limitation for the commercialization of biopolymer in comparison with petroleum derived polymer is the high cost. This article gives an overview of valorization of apple pomace for the production of biopolymer, various strategies adopted, limitations as well as future perspectives. [Display omitted] • Potential of apple waste residues (apple pomace etc.) for PHA production is studied. • Biopolymer (PHA) production from apple industrial waste residues using microbes is investigated. • Importance of biotechnology sector for PHA production was reviewed. • Life cycle assessment during the PHA production has great advantages. • Limitations and future outlook for PHA production from apple industrial wastes was reviewed. [ABSTRACT FROM AUTHOR]

In line with the Circular Economy approach, the production of polyhydroxyalkanoate (PHA) with organic waste as the feedstock may a biotechnological application to reduce waste and recover high-value materials. The potential contaminants that could transfer from bio-waste to a PHA include inorganic elements, such as heavy metals. Hence, the total content and migratability of certain elements were evaluated in several PHA samples produced from different origins and following different methods. The total content of certain elements in PHA ranged between 0.0001 (Be) and 49,500 mg kg−1 (Na). The concentrations of some alkaline (Na and K) and alkaline earth (Ca and Mg) metals were highest, which are of little environmental concern. The feedstock type and PHA stabilisation and extraction procedures affected the element contents. Several sets of experiments were conducted to evaluate the migration of elements from the PHA samples under different storage times, temperatures, and pH levels. The total contents of some heavy metals (As, Cd, Fe, Hg, Ni, Pb, and Zn) in PHA produced from fruit waste or crops (commercial PHA) were lower than those in the PHA samples produced from the mixture of the organic fraction of municipal waste and sludge from wastewater treatment. Both the PHA obtained by extraction from wet biomass (acid storage) with aqueous phase extraction reagents and commercial PHA were below the migration limits stipulated by the current Toy Safety Directive and by Commission Regulation (EU) October 2011 on plastic materials and articles intended to come into contact with food under frozen and refrigerated conditions. Image 1 • Elemental composition of a new PHA derived from organic waste is reported. • Feedstock type and production process affect the element levels of PHA. • Migratability is evaluated using different solutions and conditions. • Migratability increases under simulated acidic conditions and with heating. • Possible use of PHA was evaluated by comparison with regulations and guidelines. [ABSTRACT FROM AUTHOR]