Storage temperature and time and its influence on feed quality of fungal treated wheat straw

Intraspecies Variation Offers Potential to Improve White Rot Fungi for Increasing Degradability of Lignocellulose for Ruminants

The aim of fungal treatment of organic matter for ruminants is the improvement of its degradability. So far, such treatment appears to be time-consuming and improvement has been modest. In previous work, we observed within three white rot species that there is modest (Ceriporiopsis subvermispora) or low (Lentinula edodes and Pleurotus eryngii) variation in fiber degradation in wheat straw during seven weeks of incubation. By extending and re-examining the data from all three species, we see that strains of C. subvermispora show the largest variation and improvement in the degradability of treated wheat straw. In addition, C. subvermispora also generated the highest absolute amount of degradable organic matter, a parameter not calculated before, but is very relevant for the economic feasibility of fungal treatment. In estimating fungal growth, we found no good correlation between an increase in ergosterol and a decrease in plant biomass, indicating a variation within fungal species of the ergosterol/fungal biomass ratio and/or a variation in carbon use efficiency, which has also not been analyzed before. This work contributes to the knowledge of how fungi degrade lignocellulose and further specifies what can be targeted for breeding to make fungal pretreatment economically feasible for upgrading organic waste streams into ruminal feed.

Enhanced lignin degradation by Irpex lacteus through expanded sterilization further improved the fermentation quality and microbial community during the silage preservation process

Traditional autoclaving, slow degradation rate and preservation of biomass treated by fungi are the main factors restricting biological treatment. In our previous studies, strains with high efficiency and selective lignin degradation ability were obtained. To further solve the limiting factors of biological treatment, this paper proposed a composite treatment technology, which could replace autoclaves for fungal treatment and improve the preservation and utilization of fungal-pretreated straw. The autoclaved and expanded buckwheat straw were, respectively, degraded by Irpex lacteus for 14 days (CIL, EIL), followed by ensiling of raw materials (CK) and biodegraded straw of CIL and EIL samples with Lactobacillus plantarum for different days, respectively (CP, CIP, EIP). An expansion led to lactic acid bacteria, mold, and yeast of the samples below the detection line, and aerobic bacteria was significantly reduced, indicating a positive sterilization effect. Expansion before I. lacteus significantly enhanced lignin selective degradation by about 6%, and the absolute content of natural detergent solute was about 5% higher than that of the CIL. Moreover, EIL decreased pH by producing higher organic acids. The combination treatment created favorable conditions for ensiling. During ensiling, EIP silage produced high lactic acid about 26.83 g/kg DM and the highest acetic acid about 22.35 g/kg DM, and the pH value could be stable at 4.50. Expansion before I. lacteus optimized the microbial community for ensiling, resulting in EIP silage co-dominated by Lactobacillus, Pediococcus and Weissella, whereas only Lactobacillus was always dominant in CP and CIP silage. Clavispora gradually replaced Irpex in EIP silage, which potentially promoted lactic acid bacteria growth and acetic acid production. In vitro gas production (IVGP) in EIL was increased by 30% relative to CK and was higher than 24% in CIL. The role of expansion was more significant after ensiling, the IVGP in EIP was increased by 22% relative to CP, while that in CIP silage was only increased by 9%. Silage of fungal-treated samples reduced methane emissions by 28% to 31%. The study demonstrated that expansion provides advantages for fungal colonization and delignification, and further improves the microbial community and fermentation quality for silage, enhancing the nutrition and utilization value. This has practical application value for scaling up biological treatment and preserving the fungal-treated lignocellulose.

Study on Epoxy Resin Composite Reinforced with Rice Straw Fiber

In order to enhance the performance of the epoxy resin-prepared materials, straw fiber was used as the reinforcing base in this study. The principle of this study is to use the cellulose component exposed after the defibrillation of straw fiber can be further combined with the epoxy group. Firstly, the degree of defibrillation of straw fiber under three different pretreatment methods of acid, alkali and moist heat treatment was explored, and a control test was conducted with untreated straw fiber, which showed that the defibrillation of the straw fiber after alkali treatment was better than the other two methods. Secondly, to prove the comprehensive effect of the pretreatment method and straw fiber filling amount on the composite material performance, this paper carried out a tensile, bending, density and water absorption test. The results showed that when the straw fiber filling was 15%, the best performance of the composites was achieved by the alkali treatment, with tensile strength and tensile modulus reaching 1.89 KN and 3.92 MPa, bending strength and bending modulus reaching 2.00 KN and 81.65 MPa, average water absorption reaching 2.77%, and density reaching 0.957 g/cm3. Finally, the results were verified using Image J software was used for verification. After comparison, the material meets the basic requirements of high-density fiberboard material and provides a reference for preparing straw epoxy resin composites.

Ensiling Improved the Colonization and Degradation Ability of Irpex lacteus in Wheat Straw

To develop a non-thermal method to replace steam autoclaving for white-rot fungi fermentation, Irpex lacteus spawn was inoculated in wheat straw (WSI) or ensiled WS (WSI) at varying ratios of 10%, 20%, 30%, 40%, and 50%, and incubated at 28 °C for 28 days to determine the effects of the ensiling and inoculation ratio on the colonization and degradation ability of Irpex lacteus in wheat straw (WS). The results demonstrate that ensiling effectively inhibited the growth of aerobic bacteria and molds, as well as other harmful microorganisms in WS, which created a favorable condition for the growth of I. lacteus. After the treatment of I. lacteus, the pH of EWSI decreased to below 5, while that of WSI, except for the feedstocks of WSI-50%, was around 7, indicating that I. lacteus colonized well in the ensiled WS because the substrates dominated by I. lacteus are generally acidic. Correspondingly, except for the molds in WSI-50% samples, the counts of other microorganisms in WSI, such as aerobic bacteria and molds, were significantly higher than those in EWSI (p < 0.05), indicating that contaminant microorganisms had a competitive advantage in non-ensiled substrates. Incubation with I. lacteus did not significantly affect the cellulose content of all samples. However, the NDS content of EWSI was significantly higher than that of WSI (p < 0.05), and the hemicellulose and lignin contents were significantly lower than the latter (p < 0.05), except for the NDS and hemicellulose contents of WSI-50% samples. Correlation analysis revealed a stronger negative correlation between NDS content and the contents of hemicellulose, cellulose, and lignin in EWSI, which could be caused by the destruction of lignin and hemicellulose and the conversion from structural carbohydrates to fungal polysaccharides or other compounds in NDS form. Even for WSI-50% samples, the sugar yield of WS treated with I. lacteus improved with an increasing inoculation ratio, but the ratio was not higher than that of the raw material. However, the sugar yield of EWSI increased by 51-80%, primarily owing to the degradation of lignin and hemicellulose. Above all, ensiling improves the colonization ability of I. lacteus in WS, which promotes the degradation of lignin and hemicellulose and the enzymic hydrolysis of cellulose, so combining ensiling and I. lacteus fermentation has promising potential in the pretreatment of WS.