Second-growth and small forest clearings have little effect on the temporal activity patterns of Amazonian phyllostomid bats

Secondary forests and human-made forest gaps are conspicuous features of tropical landscapes. Yet, behavioural responses to these aspects of anthropogenically-modified forests remain poorly investigated. Here, we analyse the effects of small human-made clearings and secondary forests on tropical bats by examining the guild- and species-level activity patterns of phyllostomids sampled in the Central Amazon, Brazil. Specifically, we contrast the temporal activity patterns and degree of temporal overlap of six frugivorous and four gleaning animalivorous species in old-growth forest and second-growth forest and of four frugivores in old-growth forest and forest clearings. The activity patterns of frugivores and gleaning animalivores did not change between old-growth forest and second-growth, nor did the activity patterns of frugivores between old-growth forest and clearings. However, at the species level we detected significant differences for Artibeus obscurus (old-growth forest vs. second-growth) and Artibeus concolor (old-growth forest vs.clearings). The degree of temporal overlap was greater than random in all sampled habitats. However, whereas for frugivorous species the degree of temporal overlap was similar between old-growth forest and second-growth, for gleaning animalivores it was lower in second-growth than in old-growth forest. On the other hand, forest clearings were characterized by increased temporal overlap between frugivores. Changes in activity patterns and temporal overlap may result from differential foraging opportunities and dissimilar predation risks. Yet, our analyses suggest that activity patterns of bats in second-growth and small forest clearings, two of the most prominent habitats in humanized tropical landscapes, varies little from the activity patterns in old-growth forest

Effect of Molecules Secreted by Lactobacillus acidophilus Strain La-5 on Escherichia coli O157:H7 Colonization▿

The probiotic bacterium Lactobacillus acidophilus strain La-5 is a gut-colonizing microorganism that, when established, becomes an important part of the gastrointestinal (GI) tract microbiota. It has been shown to be effective against enterohemorrhagic Escherichia coli (EHEC) O157:H7 infection. We have previously shown that molecules released by probiotic strain La-5 influence the transcription of EHEC genes involved in colonization and quorum sensing. In this work, we report on the ability of these molecules to prevent the adherence of EHEC to epithelial cells and on its capacity to concentrate F-actin at adhesion sites. With a fluorescein-labeled phallotoxin, it was shown that La-5 cell-free spent medium (CFSM) fractions remarkably reduced attaching and effacing lesions in HeLa cells. We also observed a significant inhibition of bacterial adhesion to Hep-2 cells when they were treated with the same La-5 CFSM fractions. In order to observe if La-5 CFSM fractions exhibited the same effect in vivo, we studied the ability of luminescent EHEC constructs (LEE1::luxCDABE) to adhere to intestinal epithelial cells of specific-pathogen-free ICR mice following intragastric inoculation. Colonization of the GI tract by luminescent EHEC O157:H7 was monitored in real time with a slow-scan charge-coupled device camera. At the same time, fecal shedding of EHEC was studied. Following oral gavage of the La-5 active fraction, we observed a reduced amount of bioluminescence signal along with a decrease in fecal shedding by mice, indicating an effect on the ability of the organism to colonize the GI tract. Our results confirm past evidence of the possibility of blocking or interfering with EHEC's virulence by active molecules contained in the probiotic CFSM and identify novel therapeutic alternatives to antibiotic treatments in the fight against food-borne pathogens

Probiotics Affect Virulence-Related Gene Expression in Escherichia coli O157:H7▿

The attachment of enterohemorrhagic Escherichia coli O157:H7 (EHEC O157) to host intestinal epithelial cells is essential for the development of hemorrhagic colitis and hemolytic-uremic syndrome in humans. Genes involved in attachment are carried within a pathogenicity island named the locus of enterocyte effacement (LEE), known to be directly activated by quorum sensing (QS). In the present study, we investigated autoinducer-2 (AI-2) production and the expression of several virulence-related genes in EHEC O157 grown in the absence and presence of a Lactobacillus acidophilus-secreted molecule(s). Transcription of important EHEC O157 virulence-related genes was studied by constructing promoter-reporter fusions and reverse transcriptase PCR. Shiga toxin (Stx) production was assayed by an enzyme immunoassay. When EHEC O157 was grown in the presence of chromatographically selected fractions of L. acidophilus La-5 cell-free spent medium, we observed a significant reduction of both extracellular AI-2 concentration and the expression of important virulence-related genes, although no significant difference in Stx production was observed. We show here that L. acidophilus La-5 secretes a molecule(s) that either acts as a QS signal inhibitor or directly interacts with bacterial transcriptional regulators, controlling the transcription of EHEC O157 genes involved in colonization

Production of Pleurotus ostreatus cultivated in substrates made from two invasive weeds

The species Pleurotus ostreatus is an edible mushroom with a high commercial value, cultivated for its ease and adaptability in substrates based on agro-industrial waste. The plant species Solanum elaeagnifolium and Salsola kali are two invasive weeds that spread rapidly in crops, ruderal or urban areas, representing high-cost agricultural losses and environmental impact. The hypothesis of this research was that at least one of the weeds would increase the production and quality of P. ostreatus. The objective was to evaluate the biological efficiency and carpophore productivity ofP. ostreatus with the use of substrates elaborated and combined from S. elaeagnifolim and S. kali. The fungal cultures were carried out with substrates generated from mixtures of weeds and using wheat straw as a control; from these combinations, seven treatments and four replicates were obtained in a completely randomized design. The carpophores obtained were measured for the width and length of the pileus and stipe, total production (g), biological efficiency (%), and proximate analysis of the harvested mushrooms was performed. Maximum production was 23.30 mushrooms, with minimum of 3.67 carpophores. The width and length of the pileus were 8.30-11.70 cm and 8.40-11.40 cm, respectively. The stipe length variable showed widths of 1.40-2.30 cm and lengths of 2.80-6.20 cm. The weights obtained were up to 358.33 g, with a minimum of 95.10 g. Proximate analysis showed carpophores with the following composition: 82.25-91.37 % moisture; 1.71 to 13.66 % ash; 15.70 to 20.93 % protein; 0.40 to 1.55 % lipids and 8.60-17.7 % dry matter. The variables evaluated showed differences (p ≤ 0.05), being the substrates made with 100 % S. elaeagnifolium the ones with the highest biological efficiency, carpophore production, harvest weight and nutritional value. The species P. ostreatus proved to be efficient in providing substrate for two weeds, as well as producing carpophores with high protein content