Preliminary characterization of some Streptomyces species isolated from a composting process and their antimicrobial potential

The aim of this study was to screen Streptomycetes isolates with antimicrobial and antiviral activity, in a search for new metabolites. The isolates were obtained from a composting process, and identified based on morphological characteristics and molecular biological methods. The antimicrobial activity was determined using the double-layer agar method against 53 test organisms (bacteria, yeasts, and filamentous fungi). All isolates were grown in submerged culture, in mineral salts-starch-casein (SC) broth and ISP2 media, and the filtrate cultures were used in the assays for antibacterial and antiviral activity. Bovine Herpes virus (BoHV-I) was used for the antiviral activity. The morphological and molecular characteristics confirmed that all 25 isolates belonged to the genus Streptomyces. In the assay for antimicrobial activity, 80% of the Streptomyces isolates were able to inhibit at least one of the test organisms. Of these, 80% were active against bacteria and 45% against fungi. Eight of the isolates showed a broad spectrum of inhibitory activity; of these, the isolate Streptomyces spp. 1S was able to inhibit 46 of the test organisms, and, most importantly, the 16 Gram-negative strains were inhibited. Of the 25 isolates, 44.4% of the isolates were able to grow and produce bioactive metabolites when grown in submerged culture. Four extracts showed a cytopathic effect in 10 CCID₅₀ MDBK cell, even though no viricidal effect was observed. The results obtained with these isolates indicated good biotechnological potential of these Streptomyces strains.     

Metagenomic era for biocatalyst identification

Microbial enzymes have many known applications as biocatalysts. However, only a few of them are currently employed for biocatalysis even though an annotated collection of more than 190 billion bases is available in metagenome sequence databases from uncultured and highly diverse microbial populations. This review aims at providing conceptual and technical bases for the translation of metagenome data into both experimental and computational frameworks that facilitates a comprehensive analysis of the biocatalysts diversity space. We will also briefly present the status of the current capabilities that assess and predict catalytic potential of environmental sites and track its diversity and evolution in large-scale biocatalysis process resulting from studies applying metagenomics in association with gene fingerprinting, catabolic arrays and complementary '-omics'.     

Ectomycorrhizae and vascular plants growing in <Emphasis Type="Italic">brûlés</Emphasis> as indicators of below and above ground microecology of black truffle production areas in Navarra (Northern Spain)

The diversity below (ectomycorrhizae) and above (vascular flora) ground in brûlés of black truffle production areas have been studied together for the first time, both in plantations and in natural areas, as possible indicators of the microecology of these zones. Studies on the ectomycorrhizal community of mature plantations are scarce. However, monitoring the dynamics of such systems is important to understand the conditions that promote truffle fructification. In the study described here the most frequent ectomycorrhizae are Tuber melanosporum and Quercirrhiza quadratum. In the plantations, Q. quadratum is the most abundant morphotype and in the natural area it is Cenococcum geophilum. The development of truffle ecosystems involves the appearance of competitor species with wide networks of hyphae and rhizomorphs. On the other hand, there are few studies concerning the special composition of the vascular flora growing in brûlés. We identified 199 taxa, most of them Mediterranean or Eurosiberian xerophiles and therophytes. This is consistent with the ecology of truffle production areas (dry, sunny and stony). These plants are heavily influenced by the inhibiting substances produced by the truffle and, as a result, they suffer from inhibited growth and in some cases cannot complete their life cycle.     

Scaffold hopping from pyridones to imidazo[1,2-a]pyridines. New positive allosteric modulators of metabotropic glutamate 2 receptor

Imidazo[1,2-a]pyridines were identified via their shape and electrostatic similarity as novel positive allosteric modulators of the metabotropic glutamate 2 receptor. The subsequent synthesis and SAR are described. Potent, selective and metabolically stable compounds were found representing a promising avenue for current further studies.     

Application of High-Intensity Ultrasounds to Control the Size of Whey Proteins Particles

In this paper, we reported a new method to prepare whey protein microparticles via high-intensity ultrasound disruption. Particles morphology was characterized by confocal microscopy, and their size and distribution were analyzed by light scattering technique. Starting whey protein isolate (WPI) exhibited changes in size and distribution according to its concentration. For WPI, 7.5% (w/w) mean size was 0.7 μm, and upon sonication at ambient temperature, the size was reduced up to 0.2 μm showing the particles a rounded morphology. Sonication at room temperature of gelled WPI led to particles with sizes between 0.1 and 10 μm which had a tendency to flocculate. When WPI was submitted to sonication under heating at protein denaturation temperature, different effects were observed according to protein concentration. The particle size was reduced for the lowest WPI concentration (7.5 wt.%), did not change at 9 wt.%, but strongly increased at 12 wt.%, in comparison with the untreated sample. WPI particles of desired size in the micron range may be obtained either by sonication of gelled WPI or by sonication under heating at denaturation temperature by controlling processing variables.     

The role of matrix metalloproteinases 2 and 9 during rat tongue carcinogenesis induced by 4-nitroquinoline 1-oxide

Matrix metalloproteinases (MMPs) are implicated in a wide range of physiological and pathological processes, including morphogenesis, wound healing, angiogenesis, inflammation, and cancer. The purpose of this study was to characterize the role of MMPs as depicted by the expression of MMP-2 and MMP-9 during 4-nitroquinoline 1-oxide-induced rat tongue carcinogenesis. Male Wistar rats were distributed into three groups of 10 animals each and treated with 4-nitroquinoline 1-oxide solution at 50 ppm through their drinking water for 4, 12, and 20 weeks. Ten animals were used as control group. No histopathological abnormalities were induced in the epithelium after 4 weeks of carcinogen exposure; however, immunoexpression of MMP-2 was noticed. The same picture occurred to MMP-9, in which positive expression was detected for this immunomarker. MMP-2 and MMP-9 showed positive expression either in pre-neoplastic lesions at 12 weeks following carcinogen exposure or in well-differentiated squamous cell carcinoma induced after 20 weeks of treatment with 4NQO. Taken together, our results support the belief that MMP-2 and MMP-9 play important role during malignant transformation and conversion of oral mucosa as assessed by immunohistochemistry.