The use of an underutilized and abundant lignocellulosic feedstock residue, wheat bran, was studied for ethanol prodn. using dil. phosphoric acid pretreatment followed by fermn. using edible fungi Neurospora intermedia. Wheat bran was subjected to dil. acid pretreatment at varying acid concns. (0.5-3.0% w/v), temp. (150-210 °C), and reaction time (5-20 min). The interaction of multiple factors showed the optimum pretreatment conditions at acid concn. of 1.75% (w/v), at 190 °C for 10 min. The max. total polysaccharide yield of 0.27 ± 0.01 g/g dry biomass loading, corresponding to 66% of the theor. max. was obsd. Subsequent fermn. with N. intermedia showed 85% of the theor. max. ethanol yield from the untreated bran glucose. The effect of the dil. acid pretreatment on the functional groups of the wheat bran cellulose was detd. with 78% redn. in the cellulose crystallinity index. The validation of the dil. phosphoric acid pretreatment in a demo plant is also reported for the first time. Enzymic hydrolysis of pretreated slurry from the demo plant showed 85% total theor. yield of polysaccharides. Compared to the untreated bran biomass, an increase of 51% was obsd. in the ethanol yield following pretreatment, with a total ethanol yield of 95% theor. max. Higher yield of ethanol is also attributed to the xylose fermenting capability of the fungi. [on SciFinder(R)]

BACKGROUND : A method is described that uses dil. phosphoric acid for wheat straw pretreatment and subsequent ethanol and fungal biomass prodn. with the edible fungus Neurospora intermedia. Dil. phosphoric acid pretreatment of wheat straw was optimized at a lab. scale, and the results were validated in a biorefinery demonstration plant for the first time. The various conditions for the dil. acid pretreatment include such factors as phosphoric acid concns. (0.5-3.0% w/v), temp. (150-210 °C), and reaction time (5-20 min). RESULTS : The optimal pretreatment conditions were detd. as an acid concn. of 1.75% (w/v) at a temp. of 190 °C for 15 min, based on the max. enzymic digestibility with the min. inhibitor release. The efficiency of enzymic polysaccharide hydrolysis was 36% for untreated straw and 86% for straw pretreated with dil. phosphoric acid. Scale up of the pretreatment at a biorefinery demonstration plant improved the process, with the subsequent efficiency of polysaccharide hydrolysis being 95% of the theor. max. Ethanol fermn. of enzymically hydrolyzed wheat straw using N. intermedia showed an improvement in the ethanol yield from 29% (with untreated straw) to 94% (with dil. phosphoric acid pretreated straw) of the theor. max. CONCLUSION : This study opens up an alternative strategy for the efficient use of wheat straw for the prodn. of ethanol and edible fungal biomass in existing wheat-to-ethanol plants.

Integration of wheat straw for a biorefinery-based energy generation process by producing ethanol and biogas together with the production of high-protein fungal biomass (suitable for feed application) was the main focus of the present study. An edible ascomycete fungal strain Neurospora intermedia was used for the ethanol fermentation and subsequent biomass production from dilute phosphoric acid (0.7 to 1.2% w/v) pretreated wheat straw. At optimum pretreatment conditions, an ethanol yield of 84 to 90% of the theoretical maximum, based on glucan content of substrate straw, was observed from fungal fermentation post the enzymatic hydrolysis process. The biogas production from the pretreated straw slurry showed an improved methane yield potential up to 162% increase, as compared to that of the untreated straw. Additional biogas production, using the syrup, a waste stream obtained post the ethanol fermentation, resulted in a combined total energy output of 15.8 MJ/kg wheat straw. Moreover, using thin stillage (a waste stream from the first-generation wheat-based ethanol process) as a co-substrate to the biogas process resulted in an additional increase by about 14 to 27% in the total energy output as compared to using only wheat straw-based substrates. .[on SciFinder (R)]

Pellet formation of filamentous fungi in submerged culture is an imperative topic of fermentation research. In this study, we report for the first time the growth of filamentous ascomycete fungus,Neurospora intermedia in its mycelial pellet form. In submerged culture, the growth morphology of the fungus was successfully manipulated into growing as pellets by modifying various cultivation conditions. Factors such as pH (2.0–10.0), agitation rate (100–150 rpm), carbon source (glucose, arabinose, sucrose, and galactose), the presence of additive agents (glycerol and calcium chloride) and trace metals were investigated for their effect on the pellet formation. Of the various factors screened, uniform pellets were formed only at pH range 3.0–4.0, signifying it as the most influential factor for N. intermedia pellet formation. The average pellet size ranged from 2.38 ± 0.12 to 2.86 ± 0.38 mm. The pellet formation remained unaffected by the inoculum type used and its size showed an inverse correlation with the agitation rate of the culture. Efficient glucose utilization was observed with fungal pellets, as opposed to the freely suspended mycelium, proving its viability for fast- fermentation processes. Scale up of the pelletization process was also carried out in bench-scale airlift and bubble column reactors (4.5 L).