Novel polyurethane-degrading cutinase BaCut1 from Blastobotrys sp. G-9 with potential role in plastic bio-recycling.

Environmental pollution caused by plastic waste has become global problem that needs to be considered urgently. In the pursuit of a circular plastic economy, biodegradation provides an attractive strategy for managing plastic wastes, whereas effective plastic-degrading microbes and enzymes are required. In this study, we report that Blastobotrys sp. G-9 isolated from discarded plastic in landfills is capable of depolymerizing polyurethanes (PU) and poly (butylene adipate-co-terephthalate) (PBAT). Strain G-9 degrades up to 60% of PU foam after 21 days of incubation at 28 â„ƒ by breaking down carbonyl groups via secretory hydrolase as confirmed by structural characterization of plastics and degradation products identification. Within the supernatant of strain G-9, we identify a novel cutinase BaCut1, belonging to the esterase family, that can reproduce the same effect. BaCut1 demonstrates efficient degradation toward commercial polyester plastics PU foam (0.5 mg enzyme/25 mg plastic) and agricultural film PBAT (0.5 mg enzyme/10 mg plastic) with 50% and 18% weight loss at 37 â„ƒ for 48 h, respectively. BaCut1 hydrolyzes PU into adipic acid as a major end-product with 42.9% recovery via ester bond cleavage, and visible biodegradation is also identified from PBAT, which is a beneficial feature for future recycling economy. Molecular docking, along with products distribution, elucidates a special substrate-binding modes of BaCut1 with plastic substrate analogue. BaCut1-mediated polyester plastic degradation offers an alternative approach for managing PU plastic wastes through possible bio-recycling.

Quality Characteristics of Reduced-Fat Emulsified Sausages Made with Yeast Mannoprotein Enzymatically Prepared with a ß-1,6-glucanase.

Mannoproteins, as yeast polysaccharides, have been utilized in food the industry as dietary fibers, emulsifying agents or fat replacers. Mannoprotein MP112, produced from yeast by enzymatic hydrolysis of myxobacterial ß-1,6-glucanase GluM, exhibits excellent emulsifying properties in emulsion preparation. In this study, we aimed to examine the application of stable emulsion with the addition of mannoprotein MP112 (MP112 emulsion) to reduce the fat content of sausages. The addition of MP112 emulsion in emulsified sausages significantly reduced the fat content and increased the moisture and protein contents of emulsified sausages without the expense of their good sensory quality. Moreover, the textural properties of sausages were markedly improved with the higher hardness, chewiness and cohesiveness, especially in the 50-75% replacement ratio of MP112 emulsion. On the other hand, MP112 emulsion replacement of animal fat markedly improved the nutritional composition of emulsified sausages; they displayed a higher PUFA/SFA ratio and lower n-6/n-3 ratio due to their saturated fatty acids being replaced by poly-unsaturated fatty acids. Meanwhile, the oxidative stability of sausages was improved linearly, corresponding to the increased replacement ratio of MP112 emulsion. Our results show that mannoprotein-based emulsions could be used as potential fat alternatives in developing reduced-fat meat products.

[Screening and identification of a polyurethane-degrading bacterium G-11 and its plastic degradation characteristics].

Polyurethane (PUR) plastics is widely used because of its unique physical and chemical properties. However, unreasonable disposal of the vast amount of used PUR plastics has caused serious environmental pollution. The efficient degradation and utilization of used PUR plastics by means of microorganisms has become one of the current research hotspots, and efficient PUR degrading microbes are the key to the biological treatment of PUR plastics. In this study, an Impranil DLN-degrading bacteria G-11 was isolated from used PUR plastic samples collected from landfill, and its PUR-degrading characteristics were studied. Strain G-11 was identified as Amycolatopsis sp. through 16S rRNA gene sequence alignment. PUR degradation experiment showed that the weight loss rate of the commercial PUR plastics upon treatment of strain G-11 was 4.67%. Scanning electron microscope (SEM) showed that the surface structure of G-11-treated PUR plastics was destroyed with an eroded morphology. Contact angle and thermogravimetry analysis (TGA) showed that the hydrophilicity of PUR plastics increased along with decreased thermal stability upon treatment by strain G-11, which were consistent with the weight loss and morphological observation. These results indicated that strain G-11 isolated from landfill has potential application in biodegradation of waste PUR plastics.