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mcl-PHA
Published in Martin Koller, The Handbook of Polyhydroxyalkanoates, 2020
Camila Utsunomia, Nils Hanik, Manfred Zinn
Another important aspect of PHA producers is their condition of having non-growth-associated or growth-associated PHA production. In most cases, under nutrient-rich conditions, exponential bacterial growth is observed until the depletion of a growth-essential nutrient (e.g., nitrogen and phosphate). With an almost constant concentration of catalytically active biomass and excess carbon, PHA is synthesized and linearly accumulated. PHA production ends once the bacterium runs out of substrate or intracellular space to store the polymer. This profile characterizes non-growth-associated PHA production [41,42]. However, some bacteria, such as Azohydromonas lata (formerly known as Alcaligenes latus) and Paracoccus denitrificans, efficiently accumulate PHA under nutrient-rich conditions [43], thus possessing growth-associated PHA production.
Polyhydroxyalkanoates: Natural Degradable Biopolymers
Published in Tatiana G. Volova, Yuri S. Vinnik, Ekaterina I. Shishatskaya, Nadejda M. Markelova, Gennady E. Zaikov, Natural-Based Polymers for Biomedical Applications, 2017
Tatiana G. Volova, Yuri S. Vinnik, Ekaterina I. Shishatskaya, Nadejda M. Markelova, Gennady E. Zaikov
In succeeding years, interest in the process of biological synthesis of poly-3-hydroxybutyrate increased. It was found that P(3HB) could be synthesized by many prokaryotic microorganisms (more than 300 have been identified by now) with different efficiency, using various substrates. However, just a few species of microorganisms were chosen for commercial synthesis. They were the microorganisms that efficiently synthesized P(3HB) on a number of substrates: saccharides, methanol, hydrocarbons, and mixed hydrogen and carbon dioxide (the hydrogen-oxidizing bacteria such as Alcaligenes eutrophus, which is now known as Ralstonia eutropha, and Alcaligenes latus, the nitrogen-fixing bacterium Azotobacter vinelandii, the pseudomonade Pseudomonas oleovorans, the methylotrophs Methylomonas and Methylobacterium organophilum (Anderson and Dawes, 1990; Byron, 1987, 1994; Dawes, 1990; Braunegg et al., 1998).
Hydrogen-Oxidizing Producers of Polyhydroxyalkanoates
Published in Martin Koller, The Handbook of Polyhydroxyalkanoates, 2020
Tatiana G. Volova, Ekaterina I. Shishatskaya, Natalia O. Zhila, Evgeniy G. Kiselev
In a relatively recent study, Tanaka et al. reported CO tolerance of the hydrogen-oxidizing bacteria R. eutropha ATCC7697 and Alcaligenes latus ATCC29712 and their ability to synthesize PHA in the presence of CO; the authors isolated and studied a new microorganism, Ideonella sp. O-1, capable of synthesizing P(3HB) in high yields in the presence of CO [30]. Do et al. described Rhodospirillum rubrum culture growth and P(3HB-co-3HV) synthesis on model gas mixtures containing CO, and on the syngas produced by gasification of corn waste [31]. A study by Volova et al. in 2015 [25] reported the ability of another autotrophic hydrogen-oxidizing organism – the Seliberia carboxydohydrogena Z-1062 aerobic bacterium – to synthesize PHA in the presence of CO. Poly(3-hydroxybutyrate) yields were investigated in experiments with limiting concentrations of mineral nutrients in batch culture of S. carboxydohydrogena Z-1062 grown on gas mixtures consisting of CO2, O2, H2, and CO. CO concentrations of 10, 20, and 30% v/v did not affect synthesis of the polymer, whose content after 56-h cultivation under limiting concentrations of nitrogen and sulfur was 52.6–62.8% of biomass weight at a productivity of 0.13–0.22 g/(L·h). The inhibitory effect of CO on cell concentration was revealed at CO concentration of 30% v/v. That also caused a decrease in substrate (H2 and O2) use efficiency. Thus, this carboxydobacterium can be regarded as a potential producer of PHA from industrial hydrogenous sources.
Methods of synthesis, properties and biomedical applications of polyhydroxyalkanoates: a review
Published in Journal of Biomaterials Science, Polymer Edition, 2019
Mădălina Elena Grigore, Ramona Marina Grigorescu, Lorena Iancu, Rodica-Mariana Ion, Cătălin Zaharia, Elena Ramona Andrei
PHAs are synthesized by numerous Gram-positive bacteria: aerobic (cyanobacteria) and anaerobic (violet sulphur and sulphur-free bacteria), photosynthetic bacteria, Gram negative bacteria as well as archaea. Moreover, it has been demonstrated that some bacteria can produce PHAs without being subject to any kind of nutritional constraints, for example Alcaligenes latus strains IAM 12664T [6, 11–15]. The most used PHA is poly(3-hydroxybutyrate) (P(3HB)), which was first described by Lemoigne [16]. Later on, several bacterial strains as accumulating P(3HB) both aerobic and anaerobic were identified. The role of P(3HB) as a bacterial storage polymer having an almost similar function to starch and glycogen has been accepted in 1973. Also, it has been observed that Bacillus megaterium initiated the accumulation of P(3HB) homopolymer when the glucose to nitrogen ratio in the culture medium was bigger and subsequent intracellular degradation of P(3HB) occurred in the absence of carbon and energy sources. The assumption that 3HB monomer is the only constituent of its polymer changed after one year since its acceptance as a bacterial storage material when other types of monomers were found [17,18]. In 1974, it has been reported the discovery of other constituents of monomers in addition to the 3HB monomer in activated sludge. Currently, there are about 150 different monomers made up of PHA [19].
Bioprocess optimization of PHB homopolymer and copolymer P3 (HB-co-HV) by Acinetobacter junii BP25 utilizing rice mill effluent as sustainable substrate
Published in Environmental Technology, 2018
Poorna Chandrika Sabapathy, Sabarinathan Devaraj, Anburajan Parthiban, Preethi Kathirvel
Plastics occupy a vital role in our day-to-day lives, making it an irreplaceable material owing to its remarkable physical and chemical properties. From the ecological pursuit, non-degradable plastics pose a very jeopardic challenge on the global environment. Being unpractical to remove plastic from the ecosystem, it is advisable to replace the non-degradable plastic with degradable ones. PHAs are biodegradable polymers synthesized by many bacterial communities as an intracellular carbon reserve during nutrient starving conditions, but some bacteria like Ralstonia eutropha and Alcaligenes latus can synthesis PHAs even from nutrient non-limiting media [1]. Commercially there are many different biodegradable polymers like polylactic acid (PLA), starch and cellulose-based bioplastics, available in the market; among them PHAs seem to have promising properties to serve as an alternative for petroleum-based conventional plastics, as they are synthesized and polymerized in vivo; Above all they are easily degradable as the organisms synthesizing the polymer itself has the enzyme to depolymerize them to use as carbon source [2]. The economy for producing PHA greatly influences its commercialization, as the cost of substrate alone contributes to more than 40% in the overall production rate of PHA [3]. Utilization of various effluents as cheap substrate for the production of PHA was reported earlier by several workers [4]. Yu [5] produced PHA from starchy wastewater, agro industrial wastewater was utilized by Khardenavis et al. [6] and effluent from olive oil mill [7], dairy industry [8], paper mill [9], palm oil mill [10], biohydrogen reactor effluent [11] were also been exploited for the cost worthy production of PHA.