Antimicrobial activity of Paenibacillus polymyxa SCE2 against some mycotoxin-producing fungi.

AIMS: The purpose of this study was to investigate the antagonistic activity of Paenibacillus polymyxa strain SCE2 against mycotoxigenic fungi and to characterize the antimicrobial compound. METHODS AND RESULTS: Strain SCE2 showed a broad inhibition spectrum against different mycotoxigenic fungi. The crude supernatant obtained from strain SCE2 was filtered with Amicon Diaflo membranes, and the antimicrobial activity was detected in the fraction ranging from 0.5 to 1 kDa. The bioautography of this fraction presented two inhibition zones with both indicator strains (Micrococcus sp. and Aspergillus versicolor), suggesting that more than one substance is produced by SCE2. Based on UV-visible spectral and liquid chromatography/mass spectrometry data, phenazine-1-carboxylic acid (PCA) was characterized as the major compound present in the highest purity active fraction. Drastic alterations in the cytoplasm of A. versicolor were observed by electron microscopy. CONCLUSIONS: One of the antimicrobial substances produced by P. polymyxa SCE2 is PCA. SIGNIFICANCE AND IMPACT OF THE STUDY: The broad antifungal spectrum observed by the compound produced by SCE2 suggests that it has the potential to be used as an alternative or supplementary method to chemical pesticides against mycotoxigenic fungi. This is the first description of a phenazine produced by a member of the genus Paenibacillus.

Fructose-1,6 diphosphate as a protective agent for experimental ischemic acute renal failure.

Cold ischemia time is a risk factor for the development of acute renal failure in the immediate post-transplant period. In this study, we aimed to determine if intravenous fructose-1,6-diphosphate (FDP), given before nephrectomy, attenuates renal cell injury in a cold ischemia model. Male adult Wistar rats were subjected to infusion of either FDP 350 mg/kg (group F, n=6), an equal volume of 0.9% NaCl (group S, n=6), an equal volume/osmolality of mannitol (group M, n=6) or no infusion (group C, n=7). Kidneys were then perfused in situ with Collins solution and nephrectomy was performed. Other kidney slices were stored in Collins solution at 4 degrees C. Adenosine triphosphate (ATP) levels and lactate dehydrogenase (LDH) release were examined at 0, 24, 48 and 72 h. Other slices, obtained after 50 min immersion in Collins solution at 37 degrees C, were frozen for characterization of cytoskeletal preservation using phalloidin-FITC staining. Apical fluorescence intensity of proximal tubule cells, indicative of the F-actin concentration, was measured in a fluorescence microscope interfaced with computer image analysis system. Adenosine triphosphate levels, after up to 72 h of tissue incubation, were higher (P<0.05) in the FDP group when compared to other groups. In addition, LDH release was smaller (P<0.0001) in the FDP group. The F-actin concentration of proximal tubule cells cells was greater in the FDP group (P<0.0001). Results indicate that FDP is a useful tool to increase tissue viability in a rat kidney subjected to cold ischemia, by maintaining ATP cell content, decreasing LDH release and preventing microfilament disruption of proximal tubule cells.