The aims of this study were to evaluate the microbial diversity of different lignocellulosic biomasses during degradation under natural conditions and to isolate, select, characterise new well-adapted bacterial strains to detect potentially improved enzyme-producing bacteria. The microbiota of biomass piles of Arundo donax, Eucalyptus camaldulensis and Populus nigra were evaluated by high-throughput sequencing. A highly complex bacterial community was found, composed of ubiquitous bacteria, with the highest representation by the Actinobacteria, Proteobacteria, Bacteroidetes and Firmicutes phyla. The abundances of the major and minor taxa retrieved during the process were determined by the selective pressure produced by the lignocellulosic plant species and degradation conditions. Moreover, cellulolytic bacteria were isolated using differential substrates and screened for cellulase, cellobiase, xylanase, pectinase and ligninase activities. Forty strains that showed multienzymatic activity were selected and identified. The highest endo-cellulase activity was seen in Promicromonospora sukumoe CE86 and Isoptericola variabilis CA84, which were able to degrade cellulose, cellobiose and xylan. Sixty-two percent of bacterial strains tested exhibited high extracellular endo-1,4-ß-glucanase activity in liquid media. These approaches show that the microbiota of lignocellulosic biomasses can be considered an important source of bacterial strains to upgrade the feasibility of lignocellulose conversion for the ‘greener' technology of second-generation biofuels.

A nucleotide variability in the sequence of the gene encoding for the transmembrane protein M of canine coronavirus (CCV) is described. A total of 177 faecal samples from pups with enteritis were analysed by a PCR and n-PCR specific for CCV. Four samples, collected from a dog presenting a long-duration shedding of CCV, and a sample from another diarrhoeic dog, were found positive by PCR but negative by n-PCR. Sequence analysis of the samples revealed silent nucleotide substitutions in the binding site of the internal primer used for the n-PCR. Moreover, the nucleotide substitutions occurring over the whole fragment of the five samples analysed were similar.

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Biodegradation of lignocellulosic waste from chestnut residues is an important biological process of added value for this sector according to the Chestnut National Plan for agriculture. Dynamic parameters during biodegradation under natural conditions of chestnut burr, leaf, and plant biomass litter are reported in this study. Microbiological and physicalchemical characterisation of chestnut wastes was carried out to monitor this specific biodegradation, to understand the progress and limits of the process and to analyse the compost-like organic substance obtained. Physical-chemical parameters, such as temperature, pH, and water activity, were influenced by the composition of the raw materials and by seasonal climatic conditions. Moreover, microbiological monitoring was assessed by culture-dependent and independent methods. Cellulolytic, hemicellulolytic, and ligninolytic populations were counted to determine different microbial activity during biodegradation process. The functional microbial groups analysed showed different trends, but all were found at high concentrations (7 to 9 log CFU/g). In addition, PCR-DGGE was performed for bacterial and fungal populations to evaluate the microbial diversity. The similarity level during the process was generally very high, both for bacterial and fungal populations. These data are the first on suitable natural degradation for chestnut forests.

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Arundo donax was used to investigate the effect of the enzyme and substrate concentrations on hydrolysis, pre-hydrolysis and simultaneous saccharification and fermentation (PSSF), in comparison to simultaneous saccharification and fermentation (SSF). Hydrolysis was performed at 37 and 50 °C. At the highest biomass (10%) and enzyme (69.6 FPU/g cellulose) loadings, the highest glucose concentration (32.4 g/L) was obtained (at 50 °C). SSF resulted in a cellulose conversion (91.9%) and an ethanol concentration (19.8 g/L) higher than what was obtained using PSSF at 37 °C (86.9% and 18.8 g/L, respectively) and PSSF at 50 °C (81.6% and 17.7 g/L, respectively). A positive correlation between the cellulase concentration, cellulose conversion, and ethanol content was observed. In PSSF, the increase in the solids loadings caused a reduction in the % cellulose conversion, but the ethanol concentration in PSSF and SSF increased. SSF appeared to be the most advantageous process for bioethanol production from A. donax.

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