Insight into the cold adaptation and hemicellulose utilization of Cladosporium neopsychrotolerans from genome analysis and biochemical characterization

Abstract

The occurrence of Cladosporium in cold ecosystems has been evidenced long before, and most of the knowledge about nutrient utilization of this genus is sporadic. An alpine soil isolate C. neopsychrotolerans SL-16, showing great cold tolerance and significant lignocellulose-degrading capability, was sequenced to form a 35.9 Mb genome that contains 13,456 predicted genes. Functional annotation on predicted genes revealed a wide array of proteins involved in the transport and metabolism of carbohydrate, protein and lipid. Large numbers of transmembrane proteins (967) and CAZymes (571) were identified, and those related to hemicellulose degradation was the most abundant. To undermine the hemicellulose (xyaln as the main component) utilization mechanism of SL-16, the mRNA levels of 23 xylanolytic enzymes were quantified, and representatives of three glycoside hydrolase families were functionally characterized. The enzymes showed similar neutral, cold active and thermolabile properties and synergistic action on xylan degradation (the synergy degree up to 15.32). Kinetic analysis and sequence and structure comparison with mesophilic and thermophilic homologues indicated that these cold-active enzymes employed different cold adaptation strategies to function well in cold environment. These similar and complementary advantages in cold adaptation and catalysis might explain the high efficiency of lignocellulose conversion observed in SL-16 under low temperatures.

The “Trojan horse” strategy: Seed fungal endophyte symbiosis helps to explain the invasion success of the grass, Poa annua, in Maritime Antarctica

“…Proline is synthesized by a wide range of fungi (Jastrzębowska & Gabriel, 2015), including members of the genus Cladosporium , which, whilst apparently absent from soils around plants on King George Island, are present at very high frequency (~95%) in the tissues of P. annua plants, and particularly seeds, growing in these soils (Ballesteros et al, 2022). Cladosporium species, which are common fungal endophytes in many plant tissues and seeds (Depetris et al, 2020; Murphy et al, 2018), are adapted to cold environments and are known to synthesize proline (Ma et al, 2018), perhaps accounting for the increased concentrations of the amino acid in P. annua leaves observed here. Members of the genus confer protection against different biotic and abiotic stresses, producing and releasing beneficial secondary metabolites, biostimulants and allelochemicals, and have positive effects on crop, growth rate, seed germination and survival (Murphy et al, 2018; Pan et al, 2020; Răut et al, 2021).…”

Extremophilic Prokaryotic Endoxylanases: Diversity, Applicability, and Molecular Insights

“…As compared to the mesophilic counterparts, cold-active enzymes display optimal activity at lower temperatures (Huston, 2008). Therefore, psychrophilic enzymes are in high demand in the baking industry, where dough mixing and proofing operate below 35 • C. Several investigations have shown the significant effect of low doses of psychrophilic xylanases to attain the maximal bread volume over the mesophilic xylanases (Dornez et al, 2011;Ma et al, 2018).…”