From obtaining to degradation of PHB: A literature review. Part II

Santos, Antonio José dos; Valentina, Luiz Veriano Oliveira Dalla; Schulz, Andrey Alayo Hidalgo; Duarte, Marcia Adriana Tomaz

doi:10.17230/ingciencia.14.27.9

Cited by 14 publications

(10 citation statements)

References 34 publications

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“…For the PHB, this value is measured to be very high and depends on the type of microorganism used and the conditions adopted for the fermentation process, the growth rate of the polymer, and the final purification procedures. This parameter is very important, since it significantly influences molecular, processing, and final properties of the polymer, in particular its mechanical performance (dos Santos et al, 2018 ).…”

Section: Introductionmentioning

confidence: 99%

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In vivo and Post-synthesis Strategies to Enhance the Properties of PHB-Based Materials: A Review

Turco

Santagata

Corrado

et al. 2021

Front. Bioeng. Biotechnol.

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The transition toward “green” alternatives to petroleum-based plastics is driven by the need for “drop-in” replacement materials able to combine characteristics of existing plastics with biodegradability and renewability features. Promising alternatives are the polyhydroxyalkanoates (PHAs), microbial biodegradable polyesters produced by a wide range of microorganisms as carbon, energy, and redox storage material, displaying properties very close to fossil-fuel-derived polyolefins. Among PHAs, polyhydroxybutyrate (PHB) is by far the most well-studied polymer. PHB is a thermoplastic polyester, with very narrow processability window, due to very low resistance to thermal degradation. Since the melting temperature of PHB is around 170–180°C, the processing temperature should be at least 180–190°C. The thermal degradation of PHB at these temperatures proceeds very quickly, causing a rapid decrease in its molecular weight. Moreover, due to its high crystallinity, PHB is stiff and brittle resulting in very poor mechanical properties with low extension at break, which limits its range of application. A further limit to the effective exploitation of these polymers is related to their production costs, which is mostly affected by the costs of the starting feedstocks. Since the first identification of PHB, researchers have faced these issues, and several strategies to improve the processability and reduce brittleness of this polymer have been developed. These approaches range from the in vivo synthesis of PHA copolymers, to the enhancement of post-synthesis PHB-based material performances, thus the addition of additives and plasticizers, acting on the crystallization process as well as on polymer glass transition temperature. In addition, reactive polymer blending with other bio-based polymers represents a versatile approach to modulate polymer properties while preserving its biodegradability. This review examines the state of the art of PHA processing, shedding light on the green and cost-effective tailored strategies aimed at modulating and optimizing polymer performances. Pioneering examples in this field will be examined, and prospects and challenges for their exploitation will be presented. Furthermore, since the establishment of a PHA-based industry passes through the designing of cost-competitive production processes, this review will inspect reported examples assessing this economic aspect, examining the most recent progresses toward process sustainability.

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Section: Introductionmentioning

confidence: 99%

“…rate of the polymer, and the final purification procedures. This parameter is very important, since it significantly influences molecular, processing, and final properties of the polymer, in particular its mechanical performance (dos Santos et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

In vivo and Post-synthesis Strategies to Enhance the Properties of PHB-Based Materials: A Review

Turco

Santagata

Corrado

et al. 2021

Front. Bioeng. Biotechnol.

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“…The enzymes usually involved in this process are esterases, lipases, and proteases, which work through hydrolysis of ester linkage of the polymer. Biotic degradation is carried out mainly by PHB depolymerase, synthesised by Alcaligenes , Pseudomonas , Comamonas spp., and other species of bacteria, fungi, and algae [ 84 ].…”

Section: Bio-based Packaging: General Considerationsmentioning

confidence: 99%

The Green Era of Food Packaging: General Considerations and New Trends

et al. 2022

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Recently, academic research and industries have gained awareness about the economic, environmental, and social impacts of conventional plastic packaging and its disposal. This consciousness has oriented efforts towards more sustainable materials such as biopolymers, paving the way for the “green era” of food packaging. This review provides a schematic overview about polymers and blends of them, which are emerging as promising alternatives to conventional plastics. Focus was dedicated to biopolymers from renewable sources and their applications to produce sustainable, active packaging with antimicrobial and antioxidant properties. In particular, the incorporation of plant extracts, food-waste derivatives, and nano-sized materials to produce bio-based active packaging with enhanced technical performances was investigated. According to recent studies, bio-based active packaging enriched with natural-based compounds has the potential to replace petroleum-derived materials. Based on molecular composition, the natural compounds can diversely interact with the native structure of the packaging materials, modulating their barriers, optical and mechanical performances, and conferring them antioxidant and antimicrobial properties. Overall, the recent academic findings could lead to a breakthrough in the field of food packaging, opening the gates to a new generation of packaging solutions which will be sustainable, customised, and green.

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“…14 Enzymes from thermophiles generally have higher protein stability and activity half-life compared to their mesophile or halophile counterparts, 15 and PHB becomes amorphous at higher temperatures where it is more accessible to enzymatic depolymerization. 16,17 PHBases have been studied in a variety of organisms. PHBases hydrolyze oxoester bonds 18 using a conserved Ser-His-Asp catalytic triad motif and an oxyanion hole that drive PHB binding and catalysis.…”

Section: Introductionmentioning

confidence: 99%

“… 14 Enzymes from thermophiles generally have higher protein stability and activity half‐life compared to their mesophile or halophile counterparts, 15 and PHB becomes amorphous at higher temperatures where it is more accessible to enzymatic depolymerization. 16 , 17 …”

Section: Introductionmentioning

confidence: 99%

Bioplastic degradation by a polyhydroxybutyrate depolymerase from a thermophilic soil bacterium

et al. 2022

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As the epidemic of single‐use plastic worsens, it has become critical to identify fully renewable plastics such as those that can be degraded using enzymes. Here we describe the structure and biochemistry of an alkaline poly[(R)‐3‐hydroxybutyric acid] (PHB) depolymerase from the soil thermophile Lihuaxuella thermophila. Like other PHB depolymerases or PHBases, the Lihuaxuella enzyme is active against several different polyhydroxyalkanoates, including homo‐ and heteropolymers, but L. thermophila PHB depolymerase (LtPHBase) is unique in that it also hydrolyzes polylactic acid and polycaprolactone. LtPHBase exhibits optimal activity at 70°C, and retains 88% of activity upon incubation at 65°C for 3 days. The 1.2 Å resolution crystal structure reveals an α/β‐hydrolase fold typical of PHBases, but with a shallow active site containing the catalytic Ser‐His‐Asp‐triad that appears poised for broad substrate specificity. LtPHBase holds promise for the depolymerization of PHB and related bioplastics at high temperature, as would be required in bioindustrial operations like recycling or landfill management.

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From obtaining to degradation of PHB: A literature review. Part II

Cited by 14 publications

References 34 publications

In vivo and Post-synthesis Strategies to Enhance the Properties of PHB-Based Materials: A Review

In vivo and Post-synthesis Strategies to Enhance the Properties of PHB-Based Materials: A Review

The Green Era of Food Packaging: General Considerations and New Trends

Bioplastic degradation by a polyhydroxybutyrate depolymerase from a thermophilic soil bacterium

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