Bioconversion of straw into improved fodder: mycoprotein production and cellulolytic acivity of rice straw decomposing fungi

The potential of Trichoderma asperellum for degrading wheat straw and its key genes in lignocellulose degradation

This study explored Trichoderma asperellum's lignocellulose degradation potential in wheat straw (WS) and NaOH-treated WS via solid-state fermentation (SSF) over 30 days. Compared to the control, WS treated with T. asperellum (TW) and NaOH-treated WS with T. asperellum (TN) showed increased dry matter loss rates of 15.67 and 15.76%, respectively. Cellulose degradation reached 33.51 and 28.00%, while hemicellulose degradation increased to 31.56 and 63.86%. Crude protein (CP) content rose to 10.96 and 7.44%, and reducing sugar content to 10.86 and 12.41 mg/g, respectively. T. asperellum effectively reduced lignocellulose content and enhanced substrate nutrition, supporting subsequent uses of WS as fertilizer, feed, or for bioethanol production. Enzymatic activity and structural analyses were performed to further confirm the lignocellulose-degrading ability of T. asperellum and to analyze the degradation mechanisms. Transcriptomic analysis revealed that, compared with the control group, the TN group had 4,548, 4,399, and 6,051 differentially expressed genes (DEGs) at 5, 10, and 30 days, respectively, mainly involved in cellulose and hemicellulose degradation, carbohydrate metabolism, carbohydrate transport, glycoside hydrolases, and polysaccharide binding. T. asperellum can modify lignin by expressing dye-decolorizing peroxidase genes, and multiple key genes were identified for further research into its genetic regulation in lignocellulose degradation.

Detection of QTLs Regulating Six Agronomic Traits of Rice Based on Chromosome Segment Substitution Lines of Common Wild Rice (Oryza rufipogon Griff.) and Mapping of qPH1.1 and qLMC6.1

Wild rice is a primary source of genes that can be utilized to generate rice cultivars with advantageous traits. Chromosome segment substitution lines (CSSLs) are consisting of a set of consecutive and overlapping donor chromosome segments in a recipient's genetic background. CSSLs are an ideal genetic population for mapping quantitative traits loci (QTLs). In this study, 59 CSSLs from the common wild rice (Oryza rufipogon Griff.) accession DP15 under the indica rice cultivar (O. sativa L. ssp. indica) variety 93-11 background were constructed through multiple backcrosses and marker-assisted selection (MAS). Through high-throughput whole genome re-sequencing (WGRS) of parental lines, 12,565 mapped InDels were identified and designed for polymorphic molecular markers. The 59 CSSLs library covered 91.72% of the genome of common wild rice accession DP15. The DP15-CSSLs displayed variation in six economic traits including grain length (GL), grain width (GW), thousand-grain weight (TGW), grain length-width ratio (GLWR), plant height (PH), and leaf margin color (LMC), which were finally attributed to 22 QTLs. A homozygous CSSL line and a purple leave margin CSSL line were selected to construct two secondary genetic populations for the QTLs mapping. Thus, the PH-controlling QTL qPH1.1 was mapped to a region of 4.31-Mb on chromosome 1, and the LMC-controlling QTL qLMC6.1 was mapped to a region of 370-kb on chromosome 6. Taken together, these identified novel QTLs/genes from common wild rice can potentially promote theoretical knowledge and genetic applications to rice breeders worldwide.

Bioconversion of Straw into Improved Fodder: Preliminary Treatment of Rice Straw Using Mechanical, Chemical and/or Gamma Irradiation

Crude protein (CP) content of mechanically ground rice straw into small particles by an electric grinder and reducing value (RV) and soluble protein (SP) in the culture filtrate were lower than that of the chopped straw into 5~6 cm lengths when both ground and chopped straws were fermented with Aspergillus ochraceus, A. terreus or Trichoderma koningii, at steady conditions. The reduction rate of RV, SP and CP was 22.2, 2.4, 7.3%; 9.1, 4.9, 8.5% or 0.0, 0.0, 3.6% for the three fungi, respectively. Chemical pretreatment of straw by soaking in NH4OH for a day caused significant increase in CP of the fermented straw than the other alkali and acidic pretreatments. Gamma irradiation pretreatment of dry and wet straw with water, specially at higher doses, 100, 200 or 500 kGy, caused significant increase in RV and SP as CP in the fermented straw by any of these fungi. Chemical-physical combination pretreatment of rice straw reduced the applied dose of gamma irradiation required for increasing fermentable ability of fungi from 500 kGy to 10 kGy with approximately the same results. Significant increases in RV and SP of fermented straw generally occurred as the dose of gamma irradiation for pretreated straw, which combined with NH4OH, gradually rose. Whereas, the increase percentage in CP of fermented straw that was pretreated by NH4OH-10 kGy was 12.4%, 15.4% or 8.6% for A. ochraceus, A. terreus or T. koningii, respectively.

Bioconversion of straw into improved fodder: fungal flora decomposing rice straw

The fungal flora decomposing rice straw were investigated all over the soil of Sharkia Province, east of Nile Delta, Egypt, using the nylon net bag technique. Sixty-four straw-decomposing species belonging to 30 genera were isolated by the dilution plate method in ground rice straw-Czapek's agar medium at pH 6. The plates were incubated separately at 5℃, 25℃ and 45℃, respectively. Twenty nine species belonging to 14 genera were isolated at 5℃. The most frequent genus was Penicillium (seven species), and the next frequent genera were Acremonium (three species), Fusarium (three species), Alternaria, Chaetomium, Cladosporium, Mucor, Stachybotrys (two species) and Rhizopus stolonifer. At 25℃, 47 species belonging to 24 genera were isolated. The most frequent genus was Aspergillus (nine species), and the next frequent genera were ranked by Penicillium (five species), Chaetomium (three species), Fusarium (three species). Each of Alternaria, Cladosporium, Mucor, Myrothecium and Trichoderma was represented by two species. At 45℃, 15 species belonging to seven genera were isolated. These were seven species of Aspergillus, two species of Chaetomium and two species of Emericella, while Humicola, Malbranchea, Rhizomucor and Talaromyces were represented by one species respectively. The total counts of fungi the genera, and species per gram of dry straw were significantly affected by incubation temperature and soil analysis (P < 0.05).