Fungal chitinases: diversity, mechanistic properties and biotechnological potential

Chitin derivatives, chitosan and substituted chito-oligosaccharides have a wide spectrum of applications ranging from medicine to cosmetics and dietary supplements. With advancing knowledge about the substrate-binding properties of chitinases, enzyme-based production of these biotechnologically relevant sugars from biological resources is becoming increasingly interesting. Fungi have high numbers of glycoside hydrolase family 18 chitinases with different substrate-binding site architectures. As presented in this review, the large diversity of fungal chitinases is an interesting starting point for protein engineering. In this review, recent data about the architecture of the substrate-binding clefts of fungal chitinases, in connection with their hydrolytic and transglycolytic abilities, and the development of chitinase inhibitors are summarized. Furthermore, the biological functions of chitinases, chitin and chitosan utilization by fungi, and the effects of these aspects on biotechnological applications, including protein overexpression and autolysis during industrial processes, are discussed in this review

Criptococosis meningea e infeccción por SARS-Cov 2 en personas que viven con VIH

Introduction: Fungal infections in patients with COVID-19 was one of the most debated topics during the pandemic. Objectives: To analyze the clinical characteristics and evolution of people living with Aids (PLWHA) who presented the association of meningeal cryptococcosis and COVID-19 (group A) and compare them with those PLWHA who suffered from meningeal cryptococcosis without COVID-19 infection (group B).Materials and methods: An analytical and retrospective study was carried out in which the medical records.Results: Sixty five PLWHA with cryptococcosis diagnosed from April 2020 to May 2021 were studied. Out of these, a total of 15 PLWHA suffered from cryptococcosis and COVID-19, 14 presented meningitis (group A). Twenty-eight patients suffered from meningeal cryptococcosis and didn\u27t have covid19 (group B).Conclusions: No significant differences were observed in relationship to intracranial hypertension, initial antigenorrachia, sensorium deterioration or mortality between both groups. The detection of Cryptococcus antigen (CrAg) in serum by lateral flow assay (LFA) was of great effectivity to rapidly diagnose PLWHA with COVID-19. It was also observed that patients in both groups were late in their consultation compared to pre-pandemic cases.Introducción. Las infecciones fúngicas en pacientes con COVID-19 fue uno de los temas más debatidos durante la pandemia.Objetivo. Analizar las características clínicas y evolución de las personas viviendo con sida (PVVS) que presentaron la asociación de criptococosis meníngea y COVID-19 (grupo A) y compararlas con aquellas PVVS que padecieron criptococosis meníngea sin infección por COVID-19 (grupo B).Materiales y métodos. Se realizó un estudio analítico y retrospectivo en el que se revisaron las historias clínicas de pacientes que padecieron criptococosis meníngea entre abril de 2020 y mayo de 2021.Resultados. Se estudiaron 65 PVVS con criptococosis diagnosticadas entre abril de 2020 y mayo de 2021 (63 eran PVVS y 2 eran HIV (-)). De estos, un total de 15 PVVS padecían criptococosis y COVID-19, 14 presentaban meningitis (grupo A). veintiocho enfermos padecieron criptococosis meningea y no tuvieron covid19 (grupo B)Conclusiones. No se observaron diferencias significativas en relación a hipertensión intracraneal, antigenorraquia inicial, deterioro del sensorio o mortalidad entre ambos grupos.La detección de antígeno de Cryptococcus (CrAg) en suero por LFA fue de gran efectividad para diagnosticar rápidamente a las PVVS con COVID-19. También se observó que los pacientes de ambos grupos llegaron tarde a su consulta en comparación con los casos prepandemia

Interaction of Ammonium, Glucose, and Chitin Regulates the Expression of Cell Wall-Degrading Enzymes in Trichoderma atroviride Strain P1

Chitinolytic and glucanolytic fungal cell wall-degrading enzymes have been suggested to be primary determinants of biocontrol by Trichoderma spp. We examined the effects of ammonium, glucose, chitin, and chito-oligomers on transcription of specific genes and secretion of fungal cell wall-degrading enzymes. The genes ech42, nag1, and gluc78 were examined, as were the enzymes they encode (endochitinase CHIT42, N-acetylhexosaminidase CHIT73, and glucan exo-1,3-β-glucanase GLUC78, respectively). gluc78 could be induced by nitrogen starvation alone, while both ech42 and nag1 required nitrogen starvation and the presence of chitin for induction. Starvation for both ammonium and glucose resulted in very early expression and secretion of all cell wall-degrading enzymes examined. In the presence of low levels of ammonium (10 mM), both chito-oligomers and chitin triggered CHIT42 and CHIT40 (chitobiosidase) production. CHIT73 secretion occurred in the presence of N-acetylglucosamine and chito-oligomers, while chitin was less effective. The presence of different chito-oligomers resulted in secretion of specific N-acetylhexosaminidases, of which CHIT73 is one. Our results indicate that the expression and secretion of cell wall-degrading enzymes is nitrogen repressed, that effects of carbon and nitrogen nutrition are interactive, and that especially for chitinolytic enzymes, the inductive effect of chitin is altered by the level of ammonium or glucose in the medium