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Grazing exclusion (GE) has been applied as a suitable strategy to soil conservation worldwide, mainly in semiarid soils. However, it is unclear how GE management reduces the negative effects of overgrazing on the microbial community. In this study, we assessed the bacterial community in three different soil management belonged to a semiarid region from the Brazilian Caatinga biome, as follows: Native Caatinga (NC), Grazing exclusion (GE), and a highly degraded area by Overgrazing (OG). The bacterial community was assessed through the sequencing of the V4 region of the 16S rRNA gene. We also analyzed soil chemical and physical properties and correlated with bacterial community composition, and α- and β- diversities. Our results demonstrated that GE increases the content of soil C, N, and bacterial diversity. However, the changes in bacterial diversity were significant in a specific site (no 1), suggesting that GE strategy could be a context-dependent and a complex approach to Caatinga soils. Moreover, overgrazing might restrain the potential of bacterial diversity to sustain ecosystem functions, since non-beneficial elements (e.g., Na+ and Al3+) increased in OG, which presented a negative correlation with the bacterial community. Our study provides novel evidence that high-intensity disturbance by overgrazing could not only reduce soil fertility, but it may also restrain bacterial composition, with implications on environmental functioning. Thus, the Caatinga soil microbiome may be unable to maintain ecosystem services such as plant and animals’ development under overgrazing management.

The objective of this work was to determine the nutrient digestibility and metabolizable energy (ME) of fish silage, as well as to evaluate the effect of the dietary inclusion of fish silage meal (FSM) in diets on the performance, carcass characteristics, meat quality, sensory analysis of meat and mortadella, and economic viability of growing and finishing pigs. In the digestibility assay, 16 barrows (33.20±4.93 kg) received diets with and without FSM. The fish silage had 39.01% crude protein and 4,032 kcal kg-1 ME. In the performance assay, 32 barrows (26.00±1.68 kg) were fed diets containing different inclusion levels of FSM (0, 25, 50, and 75%). FSM, obtained from the mixture (1:1) of fish silage with corn, showed a quadratic effect on average daily gain, and the best result was obtained with the inclusion level of 25.83%. The results for feed conversion and economic viability indicate that up to 25% FSM, corresponding to 5.87% of fish silage based on dry matter, can be used in the pig growing and finishing phases.

Although microorganisms play key roles in mangrove food webs, the global knowledge of their diversity and function in these ecosystems is still scarce. Therefore, this study aimed to describe the microbiomes of pristine (TIM) and anthropized (JAG, PAC and COC) mangroves from a semiarid region of Brazil, and also to compare microbiomes from Southeast (SE) and Northeast (NE) mangroves, aiming to detect patterns related to geographic location. Pyrosequencing of four metagenomes showed that 90% of total classified sequences were assigned to Bacteria with a greater abundance of Proteobacteria (53%–60%), Bacteroidetes (7%–10%), Actinobacteria, Chloroflexi, Firmicutes and Planctomycetes (4%–7%), followed by Acidobacteria, Cyanobacteria and Verrucomicrobia (1.5%–4%) and phyla with relative abundances under 1%. The dominant proteobacterial classes were Deltaproteobacteria, Alphaproteobacteria and Gammaproteobacteria in the pristine (TIM) and in the less anthropized mangroves (JAG and PAC). Interestingly, in COC it was observed a decrease in Gammaproteobacteria with an increase in Betaproteobacteria, possibly related to its eutrophic condition. Our datasets also revealed some previously non-detected phyla in mangroves, comprising rare groups and several candidate divisions, which were previously reported for harsh environments, suggesting the involvement of these groups with the resilience of mangroves in semiarid regions. Comparative in silico analysis of SE and NE microbiomes showed similarities, but it was possible to detect a homogeneous group formed by Northeast mangroves (TIM, JAG and PAC), whereas the eutrophic mangrove (COC) clustered together to the urbanized Southeast mangrove. These results suggest that the semiarid climate might select peculiar bacterial communities and highlight the risk of microbial diversity homogenization due to anthropic actions on mangroves. Despite the detected changes in microbial composition, in general the potential metabolic pathways from these mangroves did not significantly differ. The observed functional redundancy explains the known resilience of these environments.

Maritime ports are anthropogenic interventions capable of causing serious alterations in coastal ecosystems. In this study, we examined the benthic microbial diversity and community structure under the influence of two maritime ports, Mucuripe (MUC) and Pecém (PEC), at Equatorial Atlantic Ocean in Northeast Brazil. Those seaports differ in architecture, time of functioning, cargo handling and contamination. The microbiomes from MUC and PEC were also compared in silico to 11 other globally distributed marine microbiomes. The comparative analysis of operational taxonomic units (OTUs) retrieved by PCR-DGGE showed that MUC presents greater richness and β diversity of Bacteria and Archaea than PEC. In line with these results, metagenomic analysis showed that MUC and PEC benthic microbial communities share the main common bacterial phyla found in coastal environments, although can be distinguish by greater abundance of Cyanobacteria in MUC and Deltaproteobacteria in PEC. Both ports differed in Archaea composition, being PEC port sediments dominated by Thaumarchaeota. The microbiomes showed little divergence in their potential metabolic pathways, although shifts on the microbial taxonomic signatures involved in nitrogen and sulphur metabolic pathways were observed. The comparative analysis of different benthic marine metagenomes from Brazil, Australia and Mexico grouped them by the geographic location rather than by the type of ecosystem, although at phylum level seaport sediments share a core microbiome constituted by Proteobacteria, Cyanobacteria, Actinobacteria, Tenericuteres, Firmicutes, Bacteriodetes and Euryarchaeota. Our results suggest that multiple physical and chemical factors acting on sediments as a result of at least 60 years of port operation play a role in shaping the benthic microbial communities at taxonomic level, but not at functional level.