The Impact of Mineral and Energy Supplementation and Phytogenic Compounds on Rumen Microbial Diversity and Nitrogen Utilization in Grazing Beef Cattle.

The objective of this study was to evaluate the effect of the addition of a phytogenic compound blend (PHA) containing hydrolyzable tannins, carvacrol, and cinnamaldehyde oil to mineral salt or energy supplementation on the rumen microbiota and nitrogen metabolism of grazing Nellore cattle. Eight castrated Nellore steers were distributed in a double-Latin-square 4 × 4 design, with a 2 × 2 factorial arrangement (two types of supplements with or without the addition of the PHA), as follows: energy supplement without the PHA addition (EW); energy supplement with the PHA addition (EPHA); mineral supplement without the addition of the PHA (MW); mineral supplement with the PHA addition (MPHA). Steers that received supplements with the PHA have a lower ruminal proportion of valerate (with the PHA, 1.06%; without the PHA, 1.15%), a lower ruminal abundance of Verrucomicrobia, and a tendency for lower DM digestibility (with the PHA, 62.8%; without the PHA, 64.8%). Energy supplements allowed for higher ammonia concentrations (+2.28 mg of NH3-N/dL), increased the propionate proportion (+0.29% of total VFA), and had a higher ruminal abundance of Proteobacteria and Spirochaetae phyla in the rumen. The PHA addition in the supplement did not improve nitrogen retention, reduced the ruminal proportion of valerate, and had a negative impact on both the total dry-matter digestibility and the abundance of several ruminal bacterial groups belonging to the Firmicutes and Verrucomicrobia phyla.

Unraveling a Lignocellulose-Decomposing Bacterial Consortium from Soil Associated with Dry Sugarcane Straw by Genomic-Centered Metagenomics.

Second-generation biofuel production is in high demand, but lignocellulosic biomass' complexity impairs its use due to the vast diversity of enzymes necessary to execute the complete saccharification. In nature, lignocellulose can be rapidly deconstructed due to the division of biochemical labor effectuated in bacterial communities. Here, we analyzed the lignocellulolytic potential of a bacterial consortium obtained from soil and dry straw leftover from a sugarcane milling plant. This consortium was cultivated for 20 weeks in aerobic conditions using sugarcane bagasse as a sole carbon source. Scanning electron microscopy and chemical analyses registered modification of the sugarcane fiber's appearance and biochemical composition, indicating that this consortium can deconstruct cellulose and hemicellulose but no lignin. A total of 52 metagenome-assembled genomes from eight bacterial classes (Actinobacteria, Alphaproteobacteria, Bacilli, Bacteroidia, Cytophagia, Gammaproteobacteria, Oligoflexia, and Thermoleophilia) were recovered from the consortium, in which ~46% of species showed no relevant modification in their abundance during the 20 weeks of cultivation, suggesting a mostly stable consortium. Their CAZymes repertoire indicated that many of the most abundant species are known to deconstruct lignin (e.g., Chryseobacterium) and carry sequences related to hemicellulose and cellulose deconstruction (e.g., Chitinophaga, Niastella, Niabella, and Siphonobacter). Taken together, our results unraveled the bacterial diversity, enzymatic potential, and effectiveness of this lignocellulose-decomposing bacterial consortium.

Exploring the Potential of Two Bacterial Consortia to Degrade Cellulosic Biomass for Biotechnological Applications.

This paper outlines two cellulolytic bacterial consortia named SCS and SCB, isolated from soil samples of sugarcane (Saccharum officinarum) crop field, and a sugarcane bagasse deposit in an ethanol mill. Both consortia were able to grow on different carbon sources, such as sugarcane bagasse, corn husk, peanut hulls, and carboxymethylcellulose, releasing up to 11.90 µmol/mL and 15.23 µmol/mL of glucose for SCS and SCB, respectively. In addition, SCS and SCB have several strains capable of producing cellulase, amylase, lipase, and protease. Whole genome sequencing of the SCS consortium revealed that Burkholderia was the most prevalent genus, encompassing approximately 80% of the consortia. In addition, metagenome analysis allowed the identification of genes encoding enzymes related to starch and cellulose degradation, as well as enzymes related to lipases and proteases, confirming our initial findings. The results showed that SCS and SCB had the capability to degrade cellulose, and that they were an efficient source of enzyme production, which would provide a new choice for use in different biotechnological applications.

Land use impact on potentially toxic metals concentration on surface water and resistant microorganisms in watersheds.

Soil and water resources must be conserved and protected. However, the management of production activities causes a change in the quality of these natural resources due to accumulation in soil of potentially toxic metals. The objective of the present study was to identify the variety and paths of potentially toxic metals (PTMs), such as cadmium, lead, copper, chromium, nickel and zinc, which are associated spatially and temporally to soil and water. We also intended to isolate bacteria resistant to PTMs with important characteristics to be used in bioremediation processes. Water samples were collected every two months for one year (February-December/2014) at eight sites (P1-P8) and the soil samples were collected twice (February and August/2014) from twelve sites (S1-S12). Results indicated that agricultural land use impacts the environment, increasing the concentration of potentially toxic metals, mainly copper, zinc and chromium, in soil and water due to crop management. Ten bacteria resistant to all the metals studied were isolated, which could be used as tools for bioremediation of contaminated soils and water with those metals. The results would positively contribute to land use policy, and for the development of enhanced agricultural practices.