Plastic waste worldwide is becoming a serious pollution problem for the planet. Various physical and chemical methods have been tested in attempts to remove plastic dumps. However, these have usually resulted in secondary pollution issues. Recently, the biodegradation of plastic by fungal and bacterial strains has been spotlighted as a promising solution to remove plastic wastes without generating secondary pollution. We have previously reported that a Pseudomonas aeruginosa strain isolated from the gut of a superworm is capable of biodegrading polystyrene (PS) and polyphenylene sulfide (PPS). Herein, we demonstrate the extraordinary biodegradative power of P. aeruginosa in efficiently depolymerizing four different types of plastics: PS, PPS, polyethylene (PE) and polypropylene (PP). We further compared biodegradation rates for these four plastic types and found that PE was biodegraded fastest, whereas the biodegradation of PP was the slowest. Moreover, the growth rates of P. aeruginosa were not always proportional to biodegradation rates, suggesting that the rate of bacterial growth could be influenced by the composition and properties of intermediate molecules produced during plastic biodegradation, and these may supply useful cellular precursors and energy. In conclusion, an initial screening system to select the most suitable bacterial strain to biodegrade certain types of plastic is particularly important and may be necessary to solve plastic waste problems both presently and in the future.

Plastic, a polymer synthesized from petrochemicals, is used worldwide. However, natural degradation of plastic is difficult, causing environmental pollution, with microplastics posing a serious threat to human health. In this study, we aimed to use a new screening method based on the oxidation-reduction indicator, 2,6-dichlorophenolindophenol, to isolate a polyethylene-degrading bacterium, Acinetobacter guillouiae, from insect larvae. Plastic-degrading strains are identified by the color change in the redox indicator from blue to colorless as plastic metabolism occurs. Polyethylene biodegradation by A. guillouiae was verified through weight loss, surface erosion, physiological evidence, and chemical changes on the plastic surface. In addition, we analyzed the characteristics of hydrocarbon metabolism in polyethylene-degrading bacteria. Results suggested that alkane hydroxylation and alcohol dehydrogenation were key steps in polyethylene degradation. This novel screening method will pave the way for high-throughput screening of polyethylene-degrading microorganisms and extending its application to other types of plastics may potentially address plastic pollution.

Youngkwan Song, M.D., Ki Tae Kim, M.D., Soo Jin Park, M.D., Hong Rae Kim, M.D., Ph.D., Jae Suk Yoo, M.D., Ph.D., Pil Je Kang, M.D., Ph.D., Sung-Ho Jung, M.D., Ph.D., Cheol Hyun Chung, M.D., Ph.D., Joon Bum Kim, M.D., Ph.D., Ho Jin Kim, M.D., Ph.D.. J Chest Surg -0001;0:. https://doi.org/10.5090/jcs.23.143

OBJECTIVES: This study aimed to assess the long-term outcomes of mitral valve (MV) disease depending on sex and its differences within the MV aetiology in patients undergoing MV surgery. METHODS: We reviewed 3012 patients undergoing isolated MV surgery with or without tricuspid valve (TV) surgery/ablation between January 2000 and December 2022. The primary end-points were all-cause mortality and a composite valve-related adverse events including heart failure, stroke, reoperation and infective endocarditis. Multivariate analysis with interaction terms identified independent risk factors, with median follow-up of 8.3 years (total 30 180.6 patient-years). RESULTS: Among the 3012 patients (54.8 ± 12.7 years), 1671 were females (55.5%). Rheumatic and degenerative MV diseases comprised 54.1% and 45.9%, respectively, with higher rates of rheumatic disease in females (69.7% vs 34.7%). Compared to males, females were older with higher prevalence of atrial fibrillation, TV insufficiency and advanced heart failure symptoms, consequently undergoing more MV replacements and concomitant procedures. Females showed higher rates of composite adverse outcomes (hazard ratio [HR], 1.25; 95% confidence intervals [CIs], 1.07–1.46; P = 0.006). Significant interaction was observed between sex and aetiology, with females showing higher mortality (HR 1.51; 95% CIs, 1.12–2.04; P = 0.007) and composite outcomes (HR 1.48; 95% CIs 1.15–1.91; P = 0.002) in degenerative disease (P for interaction = 0.021 and 0.016, respectively). Multivariate Cox regression demonstrated female sex as an independent risk factor for composite valve-related adverse outcomes (adjusted HR, 1.46; 95% CIs, 1.04–2.04; P = 0.028). CONCLUSIONS: Significant sex-based differences exist in MV disease patient characteristics and surgical outcomes, with females experiencing worse results, particularly in degenerative disease. Female sex was an independent risk factor for composite valve-related adverse outcomes after MV surgery. These differences suggest the need for sex-specific diagnostic criteria to reduce the disparities in patients with MV disease.