Microelectric Current Treatment Enhanced Biodegradation of Pumpkin Lignocelluloses by Trichoderma reesei RUT-C30.

A homemade microcurrent reactor was used to treat the fermentation of Trichoderma reesei. Results indicated that the yield of saccharides for T. reesei RUT-C30 cultivated in pumpkin lignocellulose broth reaches 38.86% (w/w) when a microcurrent treatment (20 mA, at the 48th hour for 60 min) was carried out, which is significantly higher than the control group (p < 0.05). Additionally, activities of endoglucanase, cellobiohydrolase, xylanase, and pectinase were significantly increased in days 3-7. Furthermore, the fungal growth was facilitated by microelectric treatment, showing a 0.57-fold increase of spore numbers at the sixth day of cultivation. Besides, the monosaccharide composition, including glucose (1.03 mg/mL), xylose (0.12 mg/mL), arabinose (0.31 mg/mL), and fructose (0.13 mg/mL), extracted from the reactor was higher than that without the current treatment. In this work, we improved the biodegradation of lignocellulosic wastes by applying a microcurrent to lignocellulose-degrading fungal cultures and provided a new idea for the lignocellulose material pretreatment and bioconversion.

Hot air treatment-induced arginine catabolism is associated with elevated polyamines and proline levels and alleviates chilling injury in postharvest tomato fruit.

BACKGROUND: To understand whether arginine catabolism might be involved in hot air (HA)-induced chilling tolerance mechanism in tomato fruit, we investigated the effect of HA treatment on endogenous arginine catabolism in relation to chilling injury. RESULTS: Tomato fruit were harvested at mature green stage and treated with HA at 38°C for 12 h and then stored at 2°C for 21 days. The effects of HA treatment on fruit chilling injury and gene expression levels or enzyme activity, and metabolites related to arginine catabolism were evaluated. HA treatment reduced the chilling injury symptoms of tomato fruit and enhanced the accumulation of endogenous polyamines, especially putrescine and proline. This accumulation is associated with the increased transcript levels of genes encoding arginase (LeARG1 and LeARG2), arginine decarboxylase (LeADC), ornithine decarboxylase (LeODC) and ornithine aminotransferase (LeOAT) at most sampling times. However, HA treatment had little effect on nitric oxide synthase activity and nitric oxide concentration. CONCLUSION: These results revealed that the reduction in chilling injury by HA treatment may be due to the accumulation of putrescine and proline induced primarily by activating the catabolism of endogenous arginine.