Pratylenchus loosi is an important root-lesion nematode that cause damage to tea plantations in Iran and all over the world. The present study reports on the characterization and evolution of three ß-1,4-engoglucanase genes Pl-eng-2, Pl-eng-3 and Pl-eng-4. The gene structure of Pl-eng-2 was fully determined with the predicted signal peptide and devoid of the linker domain and carbohydrate-binding domain, while Pl-eng-3 and Pl-eng-4 were only partially sequenced. The transcription of Pl-eng-2 was localized in the secretory esophageal glands of all life stages, but it was upregulated in male and females stages. Exon/intron structures of Pl-eng-2, Pl-eng-3 and Pl-eng-4 confirmed that they resulted from gene duplication followed by sequence and gene structure diversification with loss of linker domain and carbohydrate-binding domain during evolution. Phylogenetic analysis further confirmed that nematode endoglucanases resulted from horizontal gene transfer of a bacterial gene as Pl-eng-3 showed sister relationships with CelB cellulase of Bacillus subtilis. Silencing Pl-eng-2 by in vitro RNA interference, produced a 60% decrease of the transcript level. The reproductive ability of silenced P. loosi showed a 35% reduction of eggs and larval stages compared to untreated nematodes suggesting that this gene is involved in the early steps of invasion.

We hypothesized that rumen fluid with yeast producing cellulase enzyme can occur and also produces a high biomass compared to S. cerevisiae. Therefore, the aim of this study was to screen and isolate yeast from rumen fluids with an experimental design method. We optimized a fermentation medium containing sugarcane molasses as a carbon source and urea as a nitrogen source to measure the efficiency of biomass production and cellulase activity. Two fistulated-crossbred Holstein Friesian steers, averaging 350 ± 20 kg body weight, were used to screen and isolate ruminal yeast. The two experiments were designed. A 12 × 3 × 3 factorial was used in a completely randomized design to determine biomass and carboxymethyl cellulase activity. Factor A was isolated yeasts and S. cerevisiae. Factor B was sugarcane molasses (M) concentration. Factor C was urea (U) concentration. Potential yeast was selected for identified and analyzed as a 4 × 3 factorial use in a completely randomized design including. Factor A was incubation times. Factor B was isolated yeast strains including code H-KKU20 (as P. kudriavzevii-KKU20), I-KKU20 (C. tropicalis-KKU20), and C-KKU20 (as Galactomyces sp.-KKU20). Isolation was under aerobic conditions, resulting in a total of 11 different colonies. We noted two appearances of colonies including, asymmetric colonies of isolated yeast (indicated as A, B, C, E, and J) and ovoid colonies (coded as D, F, G, H, I, and K). The highest biomass was observed in three yeasts including codes H, I, and C-KKU20 when inoculated in 25% molasses with 1% urea (M25+U1) (p <0.01). The highest CMCase activity was observed in yeast code H-KKU20 when inoculated in all media solutions (p <0.01). Ruminal yeasts strains H-KKU20, I-KKU20, and C-KKU20 were selected for their ability to produce biomass and their CMCase enzyme synthesis. Identification of isolates H-KKU20 and I-KKU20 revealed that those isolates belonged to Pichia kudriavzevii-KKU20 and Candida tropicalis-KKU20, while C-KKU20 was identified as Galactomyces sp.-KKU20. Two strains provided maximum cell growth: P. kudriavzevii-KKU20 (9.78 and 10.02 Log cell/ml) and C. tropicalis-KKU20 (9.53 and 9.6 Log cells/ml) at 60 and 72 h of incubation time, respectively. The highest ethanol production was observed in S. cerevisiae: 76.4, 77.8, 78.5, and 78.6 g/L at 36, 48, 60, and 72 h of incubation time, respectively (p <0.01). The P. kudriavzevii-KKU20 yielded the least reducing sugar about 30.6 and 29.8 g/L at 60 and 72 h of incubation time, respectively. It could be concluded that screening and isolating yeast from rumen fluids resulted in 11 different characteristics of yeasts. The first novel yeasts discovered in the rumen fluid of cattle were Pichia kudriavzevii-KKU20, Candida tropicalis-KKU20, and Galactomyces sp.- KKU20. P. kudriavzevii-KKU20 had higher results than the other yeasts in terms of biomass production, cellulase enzyme activity, and cell number.

Corn fiber is a co-product of commercial ethanol dry-grind plants, which is processed into distillers dried grains with solubles (DDGS) and used as animal feed, yet it holds high potential to be used as feedstock for additional ethanol production. Due to the tight structural make-up of corn fiber, a pretreatment step is necessary to make the cellulose and hemicellulose polymers in the solid fibrous matrix more accessible to the hydrolytic enzymes. A pretreatment process was developed in which whole corn kernels were soaked in aqueous solutions of 2.5, 5.0, 7.5 and 10.0 wt% ammonia at 105oC for 24 h. The pretreated corn then was subjected to a conventional mashing procedure and subsequently ethanol fermentation using a commercial strain of natural Saccharomyces cerevisiae with addition of a commercial cellulase. Pretreatment of the corn with 7.5 wt% ammonia solution plus cellulase addition gave highest ethanol production, which improved the yield in fermentation using 25 wt% solid from 334 g ethanol/kg corn obtained in the control (no pretreatment and no cellulase addition) to 379 g ethanol/kg corn (a 14% increase). The process developed can potentially be implemented in existing dry-grind ethanol facilities as a “bolt-on” process for additional ethanol production from corn fiber, and this additional ethanol can then qualify as “cellulosic ethanol” by the EPA’s Renewable Fuels Standard and thereby receive RINS (Renewable Identification Numbers).