Soil microorganisms are important mediators of carbon cycling in nature. Although cellulose- and hemicellulose-degrading bacteria have been isolated from Algerian ecosystems, the information on the composition of soil bacterial communities and thus the potential of their members to decompose plant residues is still limited. The objective of the present study was to describe and compare the bacterial community composition in Algerian soils (crop, forest, garden, and desert) and the activity of cellulose- and hemicellulose-degrading enzymes. Bacterial communities were characterized by high-throughput 16S amplicon sequencing followed by the in silico prediction of their functional potential. The highest lignocellulolytic activity was recorded in forest and garden soils whereas activities in the agricultural and desert soils were typically low. The bacterial phyla Proteobacteria (in particular classes α-proteobacteria, δ-proteobacteria, and γ-proteobacteria), Firmicutes, and Actinobacteria dominated in all soils. Forest and garden soils exhibited higher diversity than agricultural and desert soils. Endocellulase activity was elevated in forest and garden soils. In silico analysis predicted higher share of genes assigned to general metabolism in forest and garden soils compared with agricultural and arid soils, particularly in carbohydrate metabolism. The highest potential of lignocellulose decomposition was predicted for forest soils, which is in agreement with the highest activity of corresponding enzymes.

• Keywords
• Algerian soils, Bacterial community, Cellulases, Decomposition, Hemicellulases, Lignocellulose,
• MeSH
• Bacteria classification   enzymology   genetics   isolation & purification   MeSH
• Bacterial Proteins genetics   metabolism   MeSH
• Cellulase genetics   metabolism   MeSH
• Ecosystem MeSH
• Phylogeny MeSH
• Glycoside Hydrolases genetics   metabolism   MeSH
• Forests MeSH
• Soil chemistry   MeSH
• Soil Microbiology * MeSH
• Publication type
• Journal Article MeSH
• Geographicals
• Algeria MeSH
• Names of Substances
• Bacterial Proteins MeSH
• Cellulase MeSH
• Glycoside Hydrolases MeSH
• hemicellulase MeSH Browser
• Soil MeSH

Due to the ability of soil bacteria to solubilize minerals, fix N2 and mobilize nutrients entrapped in the organic matter, their role in nutrient turnover and plant fitness is of high relevance in forest ecosystems. Although several authors have already studied the organic matter decomposing enzymes produced by soil and plant root-interacting bacteria, most of the works did not account for the activity of cell wall-attached enzymes. Therefore, the enzyme deployment strategy of three bacterial collections (genera Luteibacter, Pseudomonas and Arthrobacter) associated with Quercus spp. roots was investigated by exploring both cell-bound and freely-released hydrolytic enzymes. We also studied the potential of these bacterial collections to produce enzymes involved in the transformation of plant and fungal biomass. Remarkably, the cell-associated enzymes accounted for the vast majority of the total activity detected among Luteibacter strains, suggesting that they could have developed a strategy to maintain the decomposition products in their vicinity, and therefore to reduce the diffusional losses of the products. The spectrum of the enzymes synthesized and the titres of activity were diverse among the three bacterial genera. While cellulolytic and hemicellulolytic enzymes were rather common among Luteibacter and Pseudomonas strains and less detected in Arthrobacter collection, the activity of lipase was widespread among all the tested strains. Our results indicate that a large fraction of the extracellular enzymatic activity is due to cell wall-attached enzymes for some bacteria, and that Quercus spp. root bacteria could contribute at different levels to carbon (C), phosphorus (P) and nitrogen (N) cycles.

• MeSH
• Bacteria cytology   enzymology   metabolism   MeSH
• Cell Wall enzymology   MeSH
• Quercus microbiology   MeSH
• Endophytes * MeSH
• Hydrolysis MeSH
• Organic Chemicals metabolism   MeSH
• Soil chemistry   MeSH
• Rhizosphere * MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Organic Chemicals MeSH
• Soil MeSH

The role of microorganisms in litter degradation in arid and semi-arid zones, where soil and water salinization is one of the main factors limiting carbon turnover and decay, remains obscure. Heterostachys ritteriana (Amaranthaceae), a halophyte shrub growing in arid environments such as "Salinas Grandes" (Córdoba, Argentina), appears to be the main source of organic matter in the area. Little is known regarding the microorganisms associated with H. ritteriana, although they are a potential source of enzymes such as cellulolytic ones, which might be important in biotechnological fields such as bioethanol production using ionic liquids. In the present study, by studying the microbiota growing on H. ritteriana leaf litter in "Salinas Grandes," we isolated the cellulolytic fungus Fusarium equiseti LPSC 1166, which grew and degraded leaf litter under salt stress. The growth of this fungus was a function of the C substrate and the presence of NaCl. Although in vitro the fungus used both soluble and polymeric compounds from H. ritteriana litter and synthesized extracellular β-1,4 endoglucanases, its activity was reduced by 10% NaCl. Based on these results, F. equiseti LPSC 1166 can be described as a halotolerant cellulolytic fungus most probably playing a key role in the decay of H. ritteriana leaf litter in "Salinas Grandes."

• MeSH
• Biodegradation, Environmental MeSH
• Cellulose metabolism   MeSH
• Chenopodiaceae microbiology   MeSH
• Sodium Chloride metabolism   MeSH
• Fungal Proteins genetics   metabolism   MeSH
• Fusarium enzymology   genetics   metabolism   MeSH
• Glycoside Hydrolases genetics   metabolism   MeSH
• Plant Leaves microbiology   MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• arabinogalactan endo-1,4-beta-galactosidase MeSH Browser
• Cellulose MeSH
• Sodium Chloride MeSH
• Fungal Proteins MeSH
• Glycoside Hydrolases MeSH