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H2 production from cellulose, using rumen fluid as the inoculum, has been investigated in batch experiments. Methanogenic archaea were inhibited by acid pre-treatment, which also inhibited cellulolytic microorganisms, and in consequence, the conversion of cellulose to H2. Positive results were observed only with the addition of cellulase. H2 yields were 18.5 and 9.6 mmol H2 g cellulose(-1) for reactors with 2 and 4 g cellulose l(-1) and cellulase, respectively. H2 was primarily generated by the butyric acid pathway and this was followed by formation of acetic acid, ethanol and n-butanol. In reactors using 4 g cellulose l(-1) and cellulase, the accumulation of alcohols negatively affected the H2 yield, which changed the fermentation pathways to solventogenesis. PCR-DGGE analysis showed changes in the microbial communities. The phylogenetic affiliations of the bands of DGGE were 99 % similar to Clostridium sp.

In this study, a microbial consortium from an acid-treated rumen fluid was used to improve the yields of H production from paper residues in batch reactors. The anaerobic batch reactors, which contained paper and cellulose, were operated under three conditions: (1) 0.5 g paper/L, (2) 2 g paper/L, and (3) 4 g paper/L. Cellulase was added to promote the hydrolysis of paper to soluble sugars. The H yields were 5.51, 4.65, and 3.96 mmol H/g COD, respectively, with substrate degradation ranging from 56 to 65.4 %. Butyric acid was the primary soluble metabolite in the three reactors, but pronounced solventogenesis was detected in the reactors incubated with increased paper concentrations (2.0 and 4.0 g/L). A substantial prevalence of Clostridium acetobutylicum (99 % similarity) was observed in the acid-treated rumen fluid, which has been recognized as an efficient H-producing strain in addition to ethanol and n-butanol which were also detected in the reactors.

This study describes the neonatal differentiation of the Mongolian gerbil gonocytes, focusing on the relationship between its relocation to the basement membrane, apoptosis and postrelocation changes and also the distribution of androgen receptors (AR). Testes of gerbils from 1 to 35 days of age (d) were examined by high resolution light microscopy and immunocytochemistry for proteins PCNA, VASA, and AR as well as by the TUNEL method. Gonocytes were quantified according to degree of relocation into nonrelocated, relocating and relocated. Most of them were found in the center of seminiferous cords at 1 d but a small number of relocating and relocated gonocytes were already visible in the first postnatal day. After relocation, gonocytes change phenotypically to a transitional stage designated herein prospermatogonia. Both gonocyte relocation and transformation into spermatogonial lineage occur asynchronously in the seminiferous cords, mainly after 7 d. Gonocyte proliferation began before but peak after their relocation to basement membrane at the prospermatogonia stage. Higher levels of gonocyte apoptosis were found at 7 d and 21 d. From this time onward gonocytes were not found. Gonocytes and prospermatogonia showed high amounts of AR in their cytoplasm contrary to spermatogonial subtypes, indicating a possible AR inactivation in these cells. In conclusion, the process of gonocyte relocation in the gerbil extends until the second postnatal week, leads to their rapid differentiation into prospermatogonia and occurs simultaneously with the loss of androgen sensitivity. Differently from other laboratory rodents, the events regarding gonocyte maturation in the gerbil last longer and occur asynchronously in seminiferous cords. Anat Rec,

BOTTA, L.S. Paper as an alternative source for anaerobic hydrogen production. 2012.

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