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Many industrially significant compounds have been derived from natural products in the environment. Research efforts so far have contributed to the discovery of beneficial natural products that have improved the quality of life on Earth. As one of the sources of natural products, marine sponges have been progressively recognised as microbial hotspots with reports of the sponges harbouring diverse microbial assemblages, genetic material, and metabolites with multiple industrial applications. Therefore, this paper aims at reviewing the recent literature (primarily published between 2016 and 2022) on the types and functions of natural products synthesised by sponge-associated microorganisms, thereby helping to bridge the gap between research and industrial applications. The metabolites that have been derived from sponge-associated microorganisms, mostly bacteria, fungi, and algae, have shown application prospects especially in medicine, cosmeceutical, environmental protection, and manufacturing industries. Sponge bacteria-derived natural products with medical properties harboured anticancer, antibacterial, antifungal, and antiviral functions. Efforts in re-identifying the origin of known and future sponge-sourced natural products would further clarify the roles and significance of microbes within marine sponges.

Microplastics have become a significant problem in the marine environment where a wide range of marine organisms can ingest them. Biodegradable plastics or bioplastics, which are now being widely sourced as an alternative to conventional non-biodegradable plastics, are also known to breakdown into microparticles. This study aims to investigate the interaction between two types of microbeads towards the reproductive and development functions of the harpacticoid copepod, Nitokra lacustris pacifica. Polystyrene (PS) microspheres were used as the synthetic treatment, while microbeads produced from bacterial polyhydroxyalkanoates (PHA) copolymer were used as the biodegradable treatment. Exposure to microplastics at concentrations of ~ 700 microbeads mL−1 exhibited a significant reduction in algal (Nannochloropsis sp.) ingestion. No differences were observed egg production rate (9.3–10.5 eggs fem−1 day−1), but nauplius production was significantly reduced in PS microbead treatment (40%). Development time of N. lacustris pacifica from egg to adult in control (Nannochloropsis sp.) and PHA microbead treatments was significantly shorter (10.7 and 11.2 days, respectively) than in PS microbead treatment (14 days). Similarly, during the extended exposure, no differences were observed in the egg production rate, but nauplius production was significantly affected ( 60%).

In December 2019, a novel coronavirus called severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreak was reported for the first time in Wuhan, Hubei province, China. This coronavirus has been referred as Coronavirus Disease 2019 or COVID-19 by World Health Organization (WHO). The spread of COVID-19 has become unstoppable, infecting around 93.5 million people worldwide, with the infections and deaths still increasing. Today, the entire planet has changed due to the greatest threat on the planet since the introduction of this lethal disease. This pandemic has left the world in turmoil and various measures have been taken by many countries including movement control order or lockdown, to slow down or mitigate the infection. Since the lockdown has been implemented almost in all affected countries, there has been a significant reduction in anthropogenic activity, including a reduction in industrial operations, vehicle numbers, and marine-related activities. All of these changes have also led to some unexpected environmental consequences. As a result of this lockdown, it had a positive and negative impact on the environment including the aquatic environment. Hence this review will therefore focus on the good and bad perspectives of the lockdown toward the aquatic environment. © 2021 Penerbit Universiti Kebangsaan Malaysia. All rights reserved.

The production of commodity and specialty vegetable oils is increasing every year to fulfill the ever-increasing demand where the trading of oils occurs primarily via sea shipping. Spills of vegetable oil into the aquatic environment may result in detrimental effects on aquatic ecosystems. Environmental degradation of vegetable oil spills occurs mainly via microbial activity, chemical oxidation, wave and wind actions. However, the polymerization of oils can hinder their ability to naturally degrade. Thus, human intervention in the form of both short- and long-term remediation, is desirable to reduce the effects of vegetable oil spills on aquatic ecosystems. Studies have been conducted to determine how the type and concentration of the vegetable oil contamination influence its toxicity on various organisms. Some studies show that the effect of vegetable oil spills is found to be relatively short-lived and to a certain extent increase the survivability of certain organisms. However, the integrated effect of vegetable oil spills on aquatic organisms and their environment is still being researched. This review summarizes the existing knowledge on the reported occurrences of vegetable oil spills, their degradation, and their toxicity towards the surrounding aquatic environment which would be helpful in the knowledge transfer of remediation of vegetable oils.

Blockchain-integrated waste management and circular economy are emergent concepts that target minimising waste generation and fluctuations of resource commodity. Blockchain can support a circular economy and green principles by enabling information transparency, reliability and automation. Redesigning plastics by molecular tagging is the way forward to ensure synthetic plastics are kept in an infinite loop and support closed-loop recycling. The involvement of major corporations in product development and blockchain-integrated closed-loop recycling has resulted in several successful green chemical approaches toward circular plastic economy projects. Government policies and legislations are progressively supporting plastic redesigning for improving the plastic circular economy. Nevertheless, a systematic approach is required in addressing blockchain technology and plastic redesigning to effectively leverage circular economy initiatives.

Poly(3-hydroxybutyrate

Polyhydroxyalkanoates (PHAs) are bacteria derived bio-based polymers that are synthesised under limited conditions of nutritional elements with excess carbon sources. Among the members of PHAs, poly(3-hydroxybutyrate-co-4-hydroxybutyrate) [(P(3HB-co-4HB)] emerges as an attractive biomaterial to be applied in medical applications owing to its desirable mechanical and physical properties, non-genotoxicity and biocompatibility eliciting appropriate host tissue responses. The tailorable physical and chemical properties and easy surface functionalisation of P(3HB-co-4HB) increase its practicality to be developed as functional medical substitutes. However, its applicability is sometimes limited due to its hydrophobic nature due to fewer bio-recognition sites. In this review, we demonstrate how surface modifications of PHAs, mainly P(3HB-co-4HB), will overcome these limitations and facilitate their use in diverse medical applications. The integration of nanotechnology has drastically enhanced the functionality of P(3HB-co-4HB) biomaterials for application in complex biological environments of the human body. The design of versatile P(3HB-co-4HB) materials with surface modifications promise a non-cytotoxic and biocompatible material without inducing severe inflammatory responses for enhanced effective alternatives in healthcare biotechnology. The enticing work carried out with P(3HB-co-4HB) promises to be one of the next-generation materials in biomedicines which will facilitate translation into the clinic in the future.

Microplastic pollution in our environment, especially water bodies is an emerging threat to food security and human health. Inevitably, the outbreak of Covid-19 has necessitated the constant use of face masks made from polymers such as polypropylene, polyurethane, polyacrylonitrile, polystyrene, polycarbonate, polyethylene, or polyester which eventually will disintegrate into microplastic particles. They can be broken down into microplastics by the weathering action of UV radiation from the sun, heat, or ocean wave-current and precipitate in natural environments. The global adoption of face masks as a preventive measure to curb the spread of Covid-19 has made the safe management of wastes from it cumbersome. Microplastics gain access into aquaculture facilities through water sources and food including planktons. The negative impacts of microplastics on aquaculture cannot be overemphasized. The impacts includes low growth rates of animals, hindered reproductive functions, neurotoxicity, low feeding habit, oxidative stress, reduced metabolic rate, and increased mortality rate among aquatic organisms. With these, there is every tendency of microplastic pollution to negatively impact fish production through aquaculture if the menace is not curbed. It is therefore recommended that biodegradable materials rather than plastics to be considered in the production of face mask while recycle of already produced ones should be encouraged to reduce waste.

Polyhydroxyalkanoate (PHA) is a microbial storage polymer that is naturally produced by certain bacteria. This is the first study on the ability of this particular species Massilia haematophila to synthesize a PHA copolymer containing 3-hydroxyvalerate (3HV) monomer. Using the statistical design on Massilia haematophila UMTKB-2, this study highlights the optimization of poly(3-hydroxybutyrate-co-3-hydroxyvalerate), P(3HB-co-3HV), copolymer production for shaken-flask cultivation. Moreover, the mechanical and thermal features of the polymers were determined. The production of P(3HB-co-3HV) by Massilia haematophila UMTKB-2 using optimal conditions provided by response surface methodology (RSM) yielded 5.0 g/l of P(3HB-co-7 mol% 3HV), which was higher than the value obtained from unoptimized conditions such as 4.40 g/l of P(3HB-co-4mol% 3HV). This result showed a 14% increase in copolymer concentration and a two-fold increase in 3HV composition. In this study, the P(3HB-co-3HV) synthesized was determined as a block copolymer and its thermal properties were better than P(3HB). Using RSM, the optimization conditions were successfully obtained for this bacterium, and this result is a starting platform for additional studies of a larger scaled PHA production from Massilia haematophila UMTKB-2 using bioreactors.

Polyhydroxyalkanoates (PHAs) are bacteria derived bio-based polymers that are synthesised under limited conditions of nutritional elements with excess carbon sources. Among the members of PHAs, poly(3-hydroxybutyrate-co-4-hydroxybutyrate) [(P(3HB-co-4HB)] emerges as an attractive biomaterial to be applied in medical applications owing to its desirable mechanical and physical properties, non-genotoxicity and biocompatibility eliciting appropriate host tissue responses. The tailorable physical and chemical properties and easy surface functionalisation of P(3HB-co-4HB) increase its practicality to be developed as functional medical substitutes. However, its applicability is sometimes limited due to its hydrophobic nature due to fewer bio-recognition sites. In this review, we demonstrate how surface modifications of PHAs, mainly P(3HB-co-4HB), will overcome these limitations and facilitate their use in diverse medical applications. The integration of nanotechnology has drastically enhanced the functionality of P(3HB-co-4HB) biomaterials for application in complex biological environments of the human body. The design of versatile P(3HB-co-4HB) materials with surface modifications promise a non-cytotoxic and biocompatible material without inducing severe inflammatory responses for enhanced effective alternatives in healthcare biotechnology. The enticing work carried out with P(3HB-co-4HB) promises to be one of the next-generation materials in biomedicines which will facilitate translation into the clinic in the future.

Global increase in demand for food supply has resulted in surplus generation of wastes. What was once considered wastes, has now become a resource. Studies were carried out on the conversion of biowastes into wealth using methods such as extraction, incineration and microbial intervention. Agro-industry biowastes are promising sources of carbon for microbial fermentation to be transformed into value-added products. In the era of circular economy, the goal is to establish an economic system which aims to eliminate waste and ensure continual use of resources in a close-loop cycle. Biowaste collection is technically and economically practicable, hence it serves as a renewable carbon feedstock. Biowastes are commonly biotransformed into value-added materials such as bioethanol, bioplastics, biofuels, biohydrogen, biobutanol and biogas. This review reveals the recent developments on microbial transformation of biowastes into biotechnologically important products. This approach addresses measures taken globally to valorize waste to achieve low carbon economy. The sustainable use of these renewable resources is a positive approach towards waste management and promoting circular economy.

Marine sponges are acknowledged as a bacterial hotspot and resource of novel natural products or genetic material with industrial or commercial potential. However, sponge-associated bacteria are difficult to be cultivated and the production of their desirable metabolites is inadequate in terms of rate and quantity, yet bioinformatics and metagenomics tools are steadily progressing. Bacterial diversity profiles of high-microbial-abundance wild tropical marine sponges Aaptos aaptos and Xestospongia muta were obtained by sample collection at Pulau Bidong and Pulau Redang islands, 16S rRNA amplicon sequencing on Illumina HiSeq2500 platform (250 bp paired-end) and metagenomics analysis using Ribosomal Database Project (RDP) classifier. Raw sequencing data in fastq format and relative abundance histograms of the dominant 10 species are available in the public repository Discover Mendeley Data (http://dx.doi.org/10.17632/zrcks5s8xp). Filtered sequencing data of operational taxonomic unit (OTU) with chimera removed is available in NCBI accession numbers from MT464469 to MT465036.

A natural biodegradable polymer, polyhydroxyalkanoate (PHA), was adjuvanted with a vaccine seed to observe the biomaterial's ability in enhancing an immune response in rats. The adjuvant potential of PHA was tested using the whole-killed Pasteurella multocida B:2 (PMB2) vaccine in Sprague Dawley (SD) rats to detect changes in serum immunoglobulin G (IgG) and immunoglobulin M (IgM) responses. A common PHA, poly(3-hydroxybutyrate) [P(3HB)], from Bacillus megaterium UMTKB-1 was constructed into microparticles using the solvent evaporation method. Twelve SD rats were divided into four treatment groups: 1) non-treatment as negative control, 2) P(3HB) adjuvant, 3) PMB2 vaccine, and 4) adjuvanted-P(3HB)/PMB2 vaccine groups, which were intramuscularly vaccinated twice. Immunoglobulins IgG and IgM levels were used as markers of the immune response induced by the adjuvanted-P(3HB)/PMB2 vaccine and analysed over an eight-week study period. The group vaccinated specifically with adjuvanted-P(3HB)/PMB2 vaccine had higher concentrations of immunoglobulins compared to other treatment groups, hence demonstrating the potential of the adjuvant to enhance immune response. Findings showed a need to delay the delivery of the second booster dose to determine the appropriate regime for the adjuvanted-P(3HB)/PMB2 vaccine.

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (P(3HB-co-3HV)) is the most studied short-chain-length polyhydroxyalkanoates (PHA) with high application importance in various fields. The domination of high-cost propionate and valerate over other 3-hydroxyvalerate (3HV) precursors owing to their wide preference among PHA-producing bacteria has hindered the development of diverse production processes. As alkyl alcohols are mainly produced from inexpensive starting materials through oxo synthesis, they contribute a cost-effective advantage over propionate and valerate. Moreover, alkyl alcohols can be biosynthesized from natural substrates and organic wastes. Despite their great potential, their toxicity to most PHA-producing bacteria has been the major drawback for their wide implementation as 3HV precursors for decades. Although the standard PHA-producing bacteria Cupriavidus necator showed promising alcohol tolerance, the 3HV yield was discouraging. Continuous discovery of alkyl alcohols-utilizing PHA-producing bacteria has enabled broader choices in 3HV precursor selection for diverse P(3HB-co-3HV) production processes with higher economic feasibility. Besides continuous effort in searching for promising wild-type strains, genetic engineering to construct promising recombinant strains based on the understanding of the mechanisms involved in alkyl alcohols toxicity and tolerance is an alternative approach. However, more studies are required for techno-economic assessment to analyze the economic performance of alkyl alcohol-based production compared to that of organic acids.

Marine sponges are acknowledged as bacterial hotspots in the oceanic biome. Aquatic bacteria are being investigated comprehensively for bioactive complexes and secondary metabolites. Cultivable bacteria associated with different species of sea sponges in South China Sea waters adjacent to Bidong Island, Terengganu were identified. Molecular identification was accomplished using 16S rRNA gene cloning and sequencing. Fourteen bacterial species were identified and their phylogenetic relationships were analysed by constructing a neighbour-joining tree with Molecular Evolutionary Genetics Analysis 6. The identified species encompassed four bacterial classes that were Firmicutes, Actinobacteria, Alphaproteobacteria and Gammaproteobacteria known to have been associated with sponges. The potential biotechnological applications of the identified bacteria were compared and reviewed based on relevant past studies. The biotechnological functions of the 14 cultivable isolates have been previously reported, hence reinforcing that bacteria associated with sponges are an abundant resource of scientifically essential compounds. Resilience of psychrotolerant bacteria,Span laut diakui sebagai titik panas bakteria di bioma samudera. Bakteria akuatik sedang diselidiki secara komprehensif untuk kompleks bioaktif dan metabolit sekunder. Bakteria yang boleh dikulturkan dikenal pasti dari spesies span laut berlainan di perairan Laut China Selatan berdekatan Pulau Bidong, Terengganu. Pengenalpastian molekul dicapai dengan pengklonan dan penjujukan gen 16S rRNA. Empat belas spesies bakteria telah dikenalpasti dan hubungan filogenetik mereka telah dianalisis dengan membina pokok

Agro-industry by-products are abundant in various valuable compounds. Some of these raw materials are considered as a cheaper carbon source for polyhydroxyalkanoate (PHA) production when compared with pure substrates. It is however often a costly affair for industries to recover the residual carbon components. In this study, poly(3-hydroxybutyrate) [P(3HB)] was produced using a marine Bacillus megaterium UMTKB-1 strain from sweetwater, a by-product from cane sugar refining process. The bioconversion was initiated in shaken-flasks and fermenter experiments. Applications of seawater and sweetwater mixture as well as sweetwater only as PHA culture media were investigated. The produced polymer was characterized using Gas Chromatography (GC) and Gel Permeation Chromatography (GPC). P(3HB) accumulation from tested carbon sources ranged from 3 to 49 wt%. The strain could accumulate P(3HB) in saline conditions when minimal salts medium was replaced with seawater and sweetwater. The P(3HB) content was between 7 and 27 wt%. This strain was also able to grow and accumulate up to 14 wt% P(3HB) when sweetwater was the sole PHA biosynthesis medium. The weights of P(3HB) produced was in the range 3-12 × 105 with polydispersity index values ranging from 2.7 to 3.8. The agroindustry by-products have proven to be potential carbon feedstocks for P(3HB) production. The tested strain was able to grow and accumulate P(3HB) in a novel carbon substrate medium, the sweetwater. This by-product could be used as a raw material for P(3HB) production without any pretreatment.

Poly(3-hydroxybutyrate-co-4-hydroxybutyrate) [P(3HB-co-4HB)] copolymer is noted for its high biocompatibility, which makes it an excellent candidate for biopharmaceutical applications. The wild-type Cupriavidus sp. USMAA1020 strain is able to synthesize P(3HB-co-4HB) copolymers with different 4HB monomer compositions (up to 70mol%) in shaken flask cultures. Combinations of 4HB carbon precursors consisting of 1,6-hexanediol and γ-butyrolactone were applied for the production of P(3HB-co-4HB) with different 4HB molar fraction. A sharp increase in 4HB monomer composition was attained by introducing additional copies of PHA synthase gene (phaC), responsible for P(3HB-co-4HB) polymerization. The phaC of Cupriavidus sp. USMAA1020 and Cupriavidus sp. USMAA2-4 were cloned and heterologously introduced into host, wild-type Cupriavidus sp. USMAA1020. The gene dosage treatment resulted in the accumulation of 93mol% 4HB by the transformant strains when grown in similar conditions as the wild-type USMAA1020. The PHA synthase activities for both transformants were almost two-fold higher than the wild-type. The ability of the transformants to produce copolymers with high 4HB monomer composition was also tested in large scale production system using 5L and 30L bioreactors with a constant oxygen mass transfer rate. The 4HB monomer composition could be maintained at a range of 83-89mol%. The mechanical and thermal properties of copolymers improved with increasing 4HB monomer composition. The copolymers produced could be tailored for specific biopharmaceutical applications based on their properties.

Polyhydroxyalkanoate (PHA) is a well-known biodegradable bacterial polymer. The polymer is produced by some bacteria under stressed growth conditions. In nature, poly (3-hydroxybutyrate) [P(3HB)] is the most commonly found. Nonetheless, research in PHA has resulted in the production of various copolymers with improved properties and modifications to suit a variety of different applications. Identification of new bacteria strains with the ability to produce novel PHA monomers are still on going. Various cheap and renewable carbon feedstock and growth media have been identified. The production of in PHA in industrial scale fermenters have been fine-tuned using statistical approach. The production efficiency of PHA is still being experimented in order to achieve maximum yield with minimal cost. Among the different applications of PHA, much attention was gained in medical and pharmaceutical fields. This is mainly attributed to the biocompatibility of PHA. However, studies in the application of PHA in agriculture is rather limited. This chapter will survey the efforts of PHA application in agriculture and highlight the successful usage of PHA.

A significant source of microplastics is from the usage of microbeads in the market since petrochemical plastic bead is a material used in cosmetic scrubs. A possible way to counteract the problem is by the substitution of synthetic plastic to natural biodegradable polymer. Polyhydroxyalkanoate (PHA) is a general class of thermoplastic microbial polymer and it is the best alternative to some petrochemical plastics due to its biodegradability. Some PHA has earned its way into cosmetic application due to its biocompatibility. This data article reports data on the development of biodegradable microbeads by using the double emulsion solvent evaporation technique. Our data describe the extraction of biopolymer from marine bacteria that was cultivated in shaken flask culture, removal of endotoxins using oxidizing agent, the production of microbeads using a peristaltic pump with a specific flowrate and silicon tubing, and the cytotoxicity of the microbeads. Keywords: Masillia haematophilla UMTKB-2, Polyhydroxyalkanoate, Microbeads, Cosmeceutical

Bacteria capable of degrading polyhydroxyalkanoates (PHA) by secreting extracellular depolymerase enzymes were isolated from water and soil samples collected from various environments in Malaysia. A total of 8 potential degraders exhibited clear zones on poly(3-hydroxybutyrate) [P(3HB)] based agar, indicating the presence of extracellular PHA depolymerase. Among the isolates, DP5 exhibited the largest clearing zone with a degradation index of 6.0. The highest degradation activity of P(3HB) was also observed with depolymerase enzyme of DP5 in mineral salt medium containing P(3HB). Based on biochemical characterization and 16S rRNA cloning and sequencing, isolate DP5 was found to belong to the genus Acidovorax and subsequently named as Acidovorax sp. DP5. The highest extracellular depolymerase enzyme activity was achieved when 0.25% (w/v) of P(3HB) and 1 g/L of urea were used as carbon and nitrogen source, respectively, in the culture media. The most suitable assay condition of the depolymerase enzyme in response to pH and temperature was tested. The depolymerase produced by strain Acidovorax sp. DP5 showed high percentage of degradation with P(3HB) films in an alkaline condition with pH 9 and at a temperature of 40°C.

Poly(3-hydroxybutyrate-co-4-hydroxybutyrate) [P(3HB-co-4HB)] with high 4HB monomer harbors enhanced biocompatibility and mechanical properties, which are useful as implantable and absorbable biomaterial in medical and pharmaceutical fields. Transformant Cupriavidus sp. USMAA1020 with an additional PHA synthase gene, phaC was found to produce P(3HB-co-4HB) with 86 mol% of 4HB monomer composition and high PHA content of 69 wt% in shake flask cultivation using mixed substrate of 1,6-hexanediol and 1,4-butanediol. Single-stage cultivation in 3 L fermentation has confirmed the ability of this strain to produce high 4HB monomer composition of 95 mol% in large scale fermentation with 75 wt% PHA content and high PHA concentration of 18.7 g/L. Interestingly, this strain was capable of surviving higher carbon concentration (1.05 wt% C) than the wild-type strain (0.69 wt% C). The present study results in P(3HB-co-4HB) with 1.3 and 2.3-fold PHA content and concentration respectively, with the ability to accumulate 2.1-fold 4HB monomer composition higher compared to the wild-type strain. A higher specific growth rate of 0.123 h−1 accompanied by high product yield, Yp/x of 3.8 times more than the wild-type strain were also obtained. Image from TEM showed cells with PHA content of 75 wt%, whichwere occupied with significant PHA granule. This copolymer possesses an average molecular weight (M w) and a polydispersity index of 156 kDa and 3.5 respectively with a tensile strength, elongation at break and Young’s modulus of 22.9 MPa, 463.2% and 187.3 MPa respectively. This polymer has a glass transition temperature (T g) and melting temperature (T m) of −48.9 °C and 61.9 °C respectively.

We report data associated with the identification of three polyhydroxyalkanoate synthase genes (phaC) isolated from the marine bacteria metagenome of Aaptos aaptos marine sponge in the waters of Bidong Island, Terengganu, Malaysia. Our data describe the extraction of bacterial metagenome from sponge tissue, measurement of purity and concentration of extracted metagenome, polymerase chain reaction (PCR)-mediated amplification using degenerate primers targeting Class I and II phaC genes, sequencing at First BASE Laboratories Sdn Bhd, and phylogenetic analysis of identified and known phaC genes. The partial nucleotide sequences were aligned, refined, compared with the Basic Local Alignment Search Tool (BLAST) databases, and released online in GenBank. The data include the identified partial putative phaC and their GenBank accession numbers, which are Rhodocista sp. phaC (MF457754), Pseudomonas sp. phaC (MF437016), and an uncultured bacterium AR5-9d_16 phaC (MF457753).

Background The production cost and the material properties of polyhydroxyalkanoate (PHA), a biodegradable plastic are common issues of debate. It has become a constant challenge for researchers to find suitable and relatively cheap carbon substrates. This study has investigated the production of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV)], using a combination of fatty acids and alcohols. The fermentation process described in this study also highlights the potential use of 1-pentanol for the generation of 3HV monomer, in contrast to odd carbon numbered volatile fatty acids, which are known to exert some levels of toxicity towards the cells. Results Among the various mixtures of fatty acids and 3HV precursors, the mixture of 0.50 wt% C oleic acid and 0.06 wt% C 1-pentanol was found suitable for the production of this copolymer. It was found that Cupriavidus sp. USMAA2-4 could produce up to 56 wt% of P(3HB-co-3HV) with 8 mol% 3HV monomer units. The 3HV monomer composition was also successfully regulated in the range 3–66 mol% by manipulating the culture conditions. The number average molecular weight of the copolymer produced was in the range 217–351 kDa. Conclusion The findings of this study might be used as a platform for scale-up production of 3HV copolymers with different monomer compositions using mixtures of oleic acid and alcohols, namely 1-pentanol for a sustainable production process.© 2012 Society of Chemical Industry

Polyhydroxyalkanoate (PHA) is a potential substitute for some petrochemical-based plastics. This biodegradable plastic is derived from microbial fermentation using various carbon substrates. Since carbon source has been identified as one of the major cost-absorbing factors in PHA production, cheap and renewable substrates are currently being investigated as substitutes for existing sugar-based feedstock. Plant oils have been found to result in high-yield PHA production. Malaysia, being the world's second largest producer of palm oil, is able to ensure continuous supply of palm oil products for sustainable PHA production. The biosynthesis and characterization of various types of PHA using palm oil products have been described in detail in this review. Besides, by-products and waste stream from palm oil industry have also demonstrated promising results as carbon sources for PHA biosynthesis. Some new applications in cosmetic and wastewater treatment show the diversity of PHA usage. With proper management practices and efficient milling processes, it may be possible to supply enough palm oil-based raw materials for human consumption and other biotechnological applications such as production of PHA in a sustainable manner.

This study investigates the biosynthesis and characterization of P(3HB- co -3HV- co -3HHx) terpolymer from mixtures of palm kernel oil and 3HV-precursors by using recombinant Cupriavidus necator PHB − 4/pBBREE32d13. Sodium valerate and propionate have been evaluated for the generation of 3HV monomers. The feeding time of these precursors was a crucial factor that significantly affected the 3HV molar fractions, which ranged from 2 to 60 mol%. Sodium valerate was generally the better precursor in initiating the accumulation of 3HV monomers while maintaining high cell dry weight (7.9 g/L) and good PHA accumulation (79 wt%). However, the 3HHx molar fractions in the terpolymers at 72 h were consistent at about 2–7 mol%. P(3HB- co -3HV) copolymers have been known to exhibit approximately the same degree of crystallinity throughout a wide range of 3HV composition. Interestingly, in this study, terpolymers containing 58 mol% 3HB, 39 mol% 3HV and 3 mol% 3HHx showed elastomeric behavior. This study demonstrates the suitability of palm kernel oil as the main carbon source and both sodium propionate and sodium valerate as 3HV-precursors for the synthesis of novel compositions of P(3HB- co -3HV- co -3HHx) terpolymers with interesting properties.