Poly(butylene adipate-co-terephthalate) biodegradation by Purpureocillium lilacinum strain BA1S.

Poly(butylene adipate-co-terephthalate) (PBAT), a promising biodegradable aliphatic-aromatic copolyester material, can be applied as an alternative material to reduce the adverse effects of conventional plastics. However, the degradation of PBAT plastics in soil is time-consuming, and effective PBAT-degrading microorganisms have rarely been reported. In this study, the biodegradation properties of PBAT by an elite fungal strain and related mechanisms were elucidated. Four PBAT-degrading fungal strains were isolated from farmland soils, and Purpureocillium lilacinum strain BA1S showed a prominent degradation rate. It decomposed approximately 15 wt.% of the PBAT films 30 days after inoculation. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and Liquid chromatography mass spectrometry (LC‒MS) were conducted to analyze the physicochemical properties and composition of the byproducts after biodegradation. In the presence of PBAT, the lipolytic enzyme activities of BA1S were remarkably induced, and its cutinase gene was also significantly upregulated. Of note, the utilization of PBAT in BA1S cells was closely correlated with intracellular cytochrome P450 (CYP) monooxygenase. Furthermore, CreA-mediated carbon catabolite repression was confirmed to be involved in regulating PBAT-degrading hydrolases and affected the degradation efficiency. This study provides new insight into the degradation of PBAT by elite fungal strains and increases knowledge on the mechanism, which can be applied to control the biodegradability of PBAT films in the future. KEY POINTS: • Purpureocillium lilacinum strain BA1S was isolated from farmland soils and degraded PBAT plastic films at a prominent rate. • The lipolytic enzyme activities of strain BA1S were induced during coculture with PBAT, and the cutinase gene was significantly upregulated during PBAT degradation. • CreA-mediated carbon catabolite repression of BA1S plays an essential role in regulating the expression of PBAT-degrading hydrolases.

A change of PD-1/PD-L1 expression on peripheral T cell subsets correlates with the different stages of Alzheimer's Disease.

BACKGROUND: Immune checkpoints are a set of costimulatory and inhibitory molecules that maintain self-tolerance and regulate immune homeostasis. The expression of immune checkpoints on T cells in malignancy, chronic inflammation, and neurodegenerative diseases has gained increasing attention. RESULTS: To characterize immune checkpoints in neurodegenerative diseases, we aimed to examine the expression of the immune checkpoint PD-1/PD-L1 in peripheral T cells in different Alzheimer's disease (AD) patients. To achieve this aim, sixteen AD patients and sixteen age-matched healthy volunteers were enrolled to analyze their CD3+ T cells, CD3+CD56+ (neural cell adhesion molecule, NCAM) T cells, CD4+/CD8+ T cells, and CD4+/CD8+CD25+ (interleukin-2 receptor alpha, IL-2RA) T cells in this study. The expression of PD-1 on T cells was similar between the AD patients and healthy volunteers, but increased expression of PD-L1 on CD3+CD56+ T cells (natural killer T cells, NKT-like), CD4+ T cells (helper T cells, Th), CD4+CD25+ T cells, and CD8+ T cells (cytotoxic T lymphocytes, CTL) was detected in the AD patients. In addition, we found negative correlations between the AD patients' cognitive performance and both CD8+ T cells and CD8+CD25+ T cells. To identify CD8+ T-cell phenotypic and functional characteristic differences between the healthy volunteers and AD patients in different stages, a machine learning algorithm, t-distributed stochastic neighbor embedding (t-SNE), was implemented. Using t-SNE enabled the above high-dimensional data to be visualized and better analyzed. The t-SNE analysis demonstrated that the cellular sizes and densities of PD-1/PD-L1 on CD8+ T cells differed among the healthy, mild AD, and moderate AD subjects. CONCLUSIONS: Our results suggest that changes in PD-1/PD-L1-expressing T cells in AD patients' peripheral blood could be a potential biomarker for monitoring disease and shed light on the AD disease mechanism. Moreover, these findings indicate that PD-1/PD-L1 blockade treatment could be a novel choice to slow AD disease deterioration.

Biodegradation of PBSA Films by Elite Aspergillus Isolates and Farmland Soil.

Plastic films are widely used in current agricultural practices; however, most mulch films used are discarded and buried in the land after harvest, having adverse environmental impacts. To solve this environmental problem, the demand for biodegradable mulch has been increasing in recent years. Polybutylene succinate-co-adipate (PBSA) is a biodegradable polymer with good ductility and can be used for packaging and mulching. In this study, we isolated two elite fungal strains for PBSA degradation from farmlands, i.e., Aspergillus fumigatus L30 and Aspergillus terreus HC, and the latter showed better degradation ability than the former. It is noteworthy that biodegradation of PBSA by A. terreus is reported for the first time, which revealed unique characteristics. In the soil burial test, even the soil with relatively poor degradation ability could be improved by the addition of elite fungal mycelia. In substrate specificity analyses of soil samples, PBSA could induce the synthesis of lipolytic enzymes of indigenous microbes to degrade substrates with medium and long carbon chains in soil. Furthermore, PBSA residues or fungal mycelia supplementation in soils had no adverse effect on the seed germination rate, seedling growth, or mature plant weight of the test green leafy vegetable. Taken together, the results of this study not only advance our understanding of the biodegradation of PBSA films by filamentous fungi but also provide insight into improving the efficiency of biodegradation in soil environments.