Effect Of Cell Wall Degrading Enzymes Research Articles

Ultrasound-Assisted Multi-Enzyme Extraction for Highly Efficient Extraction of Polysaccharides from Ulva lactuca.

Ulva polysaccharides present several physiological activities including antiviral, antitumor and anti-plasmodial effects. However, current processing usually results in low yields and high prices, thus lacking commercialization potential. The aim of this study was to develop an efficient method for the extraction of Ulva polysaccharides with high biological activity. The effect of cell wall-degrading enzymes including cellulase, hemicellulase, pectinase and protease on Ulva polysaccharide extraction was studied by statistical mixing design. Using the most effective enzyme preparations as the basic components, the optimal proportions of the enzyme mixture were determined as follows: cellulase 35.3%, pectinase 34.5%, alkaline protease 30.2%, which increased the polysaccharide yield from 6.43% in the absence of enzymes to 26.68%. Subsequently, through response surface analysis, the optimal conditions were determined: enzyme concentration of 1.5%, enzymatic time of 1.1 h, ultrasonic time of 90 min and enzymatic temperature of 60 °C. Under the optimal extraction conditions, the extraction yield of Ulva polysaccharides could be increased to 30.14%. Moreover, extracted polysaccharides exhibit strong antioxidant properties in DPPH, ABTS, hydroxyl radical, superoxide radical and H2O2-induced cellular damage models. This study laid a solid foundation for the use and development of Ulva polysaccharides.

Secondary Metabolites from Streptomyces araujoniae S-03 Show Biocontrol Potential against Rhododendron Root Rot Caused by Phytophthora cinnamomi

Phytophthora cinnamomi is a harmful microorganism that can infect Cinnamomum plants and cause the rotting of plant roots. It has been reported as infecting nearly 5000 types of plants worldwide, such as avocado trees, macadamia trees, and oak and chestnut trees, and is listed among the 10 most destructive oomycetes and the 100 most severely invasive species globally. A number of chemical agents have been applied in the control of phytophthora rot diseases because of their easy application and rapid effects. However, with the extensive use of chemical agents, P. cinnamomi has developed resistance. More importantly, it has damaged the ecological environment and affected human health. Given that biological control should be safe and effective, the screening of biocontrol strains with highly effective antagonistic effects is regarded as the primary means to control P. cinnamomi. In this study, a bacterial strain was isolated from the soil of healthy rhododendron, located near to diseased rhododendron plants, and identified as Streptomyces araujoniae, named S-03, which inhibited P. cinnamomi. The plate antagonism assay showed that S-03 could effectively bend the hyphae, reduce the number of branches, and even break them, destroying the integrity of the hyphal cell membrane to inhibit the growth of P. cinnamomi. Moreover, strain S-03 also could inhibit the activity of P. cinnamomi cell wall-degrading enzymes. To analyze the inhibitory mechanism of S-03, the effects of cell wall-degrading enzymes, secondary metabolites, and volatile substances produced by S-03 on P. cinnamomi were assessed. It was found that the fermentation broth of S-03 had a strong inhibitory effect on P. cinnamomi which means metabolites play a part in inhibition. The active substance of S-03 was initially separated and purified by ethyl acetate extraction and silica gel column chromatography and had the properties of small molecules, low polarity, and solubility in methanol. The biocontrol effect was detected in the host plants and indicated that S-03 could effectively protect rhododendron from P. cinnamomi infection. Overall, the present study findings provide compelling evidence that Streptomyces S-03 could be a biocontrol agent against plant diseases caused by P. cinnamomi.

Simultaneous saccharification and fermentation (SSF) of non-starch polysaccharides and starch from fresh tuber of Canna edulis ker at a high solid content for ethanol production

Canna edulis ker is a potential feedstock for ethanol production because of its low nutrition requirements and the high starch content of its tubers. The processing of C. edulis is limited by the high viscosity of the biomass. In this study, cell wall degrading enzymes (CWDEs) containing acid xylanase and β-glucanase were successful in reducing the viscosity (from 167.30 Pa s to 8.66 Pa s) at 50 °C for 120 min. The effect of CWDEs on simultaneous saccharification and fermentation (SSF) was investigated. Addition of CWDEs before SSF, resulted in an increase in total sugar and fermentable sugar. Meanwhile, the viscosity decreased sharply from approximately 200.00 Pa s to 2.98 Pa s, thereby improving the fermentation parameters and the mass fraction of the theoretical ethanol yield was 94.5%. Only special demand of nutritional ingredients was nitrogen, urea at 750 mg kg−1 was found to be suitable for this purpose. In the verification experiments, the mass fraction of the theoretical ethanol yield in a 5 L fermentor was 98.3%. In conclusion, the pretreatment with CWDEs has significant effect on high level ethanol production using roots and tubers on an industrial scale from the biomass utilization efficiency and economic standpoint.

Resistance of young versus old tobacco leaves to necrotrophs, fusaric acid, cell wall-degrading enzymes and autolysis of membrane lipids

Infection with necrotrophs, Alternaria alternata or Botrytis cinerea caused more severe symptoms on old than young tobacco leaves. Much higher amounts of fusaric acid were required to induce necrosis in young leaves compared with older leaves. Similarly fusaric acid caused higher leakage of ions from older leaf discs than from younger discs. Leaf slices from younger leaves were more resistant to pectinase and cellulase enzymes. Protoplasts from younger leaves were more tolerant to the toxic effect of cell wall-degrading enzymes than protoplasts from older leaves. These differences were related to lipid content. The amount of phospho- and galactolipids was higher while the amount of free sterols was lower in juvenile leaf tissues. The autolysis of phospholipids was much higher in homogenates from older leaves, suggesting that infection caused cell decompartmentalization resulting from a more rapid degradation of membranes in senescent tissues compared to young leaves.