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Sp. Isolated (sp + isolated)
Selected AbstractsFactors affecting biodegradation of 2-chlorophenol by Alcaligenes sp. in aerobic reactorsENVIRONMENTAL TOXICOLOGY, Issue 4 2001A. Gallego Abstract The influence of variations in carbon source concentration, cell inocula, pH, presence of other substrates, and other organisms on the biodegradation of 2-chlorophenol (2-CP) was studied for Alcaligenes sp. isolated from natural sources. Assays of biodegradation were performed in batch and continuous-flow fluidized-bed aerobic reactors. Evaluation of biodegradation was performed by determining total phenols, chemical oxygen demand (COD), and 2-CP by ultraviolet (UV) spectrophotometry. Measurement of microbial growth was carried out by the plate count method. Bioassays of acute toxicity were performed to evaluate detoxification by using Daphnia magna. Results obtained show that under batch conditions with initial inocula of 106 cells/mL the strain grew exponentially with 100, 200, and 300 mg/L of 2-CP within 48 hr. A lag period was observed with low cell density inocula (105 cells/mL). The strain showed marked delay in the biodegradation of 2-CP at pH 5. Removal of target substrate from mixtures containing other carbon sources demonstrated the possibility of concurrent growth. Mineralization of 2-CP was assessed by gas chromatography carried out at the end of the batch assays and at the exit of the continuous-flow reactor. The presence of other organisms (bacteria, rotifers, ciliate, and algae) that developed in the fluidized-bed reactor did not affect the efficacy of the biodegradation of 2-CP. The removal of 2-CP in the two assayed systems was over 97% in all cases. Toxicity was not detected at the exit of the continuous reactor. © 2001 John Wiley & Sons, Inc. Environ Toxicol 16: 306,313, 2001 [source] Effect of salinity on denitrification under limited single carbon source by Marinobacter sp. isolated from marine sedimentJOURNAL OF BASIC MICROBIOLOGY, Issue 3 2010Miyo Nakano Abstract Marinobacter comprises Gram-negative, aerobic, motile, and rod-shaped bacteria within the ,-subclass of the Proteobacteria and is known to be halophilic or halotolerant, heterotrophic neutrophile. Two strains classified as belonging to Marinobacter, named PAD-2 and SeT-1, were isolated from marine sediment. The most closely related species of PAD-2 and SeT-1 are M. alkaliphilus and M. guinea, respectively. The strain PAD-2 exhibited remarkably higher denitrification at concentrations of 0.5 to 1 M NaCl (3,6% w/w) than at other salinities (2 and 3 M NaCl, 12,18% w/w), and optimal denitrification was observed in media with 0.5 M NaCl. The effect of pH on denitrification by strain PAD-2 was also examined, and the optimum denitrification occurred at neutral pH rather than under alkaline conditions. Overall, strain PAD-2 appears to be a novel halotolerant species belonging to the genus Marinobacter that shares many characteristics, such as substrate utilization profile and optimum NaCl concentration for growth with M. alkaliphilus. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Fungistatic Activity of Heat-Treated Flaxseed Determined by Response Surface MethodologyJOURNAL OF FOOD SCIENCE, Issue 6 2008Y. Xu ABSTRACT:, The objective of this study was to evaluate the effect of heat treatment on the fungistatic activity of flaxseed (Linum usitatissimum) in potato dextrose agar (PDA) medium and a fresh noodle system. The radial growth of Penicillium chrysogenum, Aspergillus flavus, and a Penicillium sp. isolated from moldy noodles, as well as the mold count of fresh noodle enriched with heat treated flaxseed, were used to assess antifungal activity. A central composite design in the response surface methodology was used to predict the effect of heating temperature and time on antifungal activity of flaxseed flour (FF). Statistical analysis determined that the linear terms of both variables (that is, heating temperature and time) and the quadratic terms of the heating temperature had significant (P < 0.05) effects on the radial growth of all 3 test fungi and the mold count log-cycle reduction of fresh noodle. The interactions between the temperature and time were significant for all dependent variables (P < 0.05). Significant reductions in antifungal activities were found when FF was subjected to high temperatures, regardless of heating time. In contrast, prolonging the heating time did not substantially affect the antifungal activities of FF at low temperature. However, 60% of the antifungal activity was retained after FF was heated at 100 °C for 15 min, which suggests a potential use of FF as an antifungal additive in food products subjected to low to mild heat treatments. [source] Antifungal Activity Stability of Flaxseed Protein Extract Using Response Surface MethodologyJOURNAL OF FOOD SCIENCE, Issue 1 2008Y. Xu ABSTRACT:, The stability of the antifungal activity of flaxseed (Linum usitatissimum) protein extract was evaluated in this study. Response surface methodology (RSM) using Box,Behnken factorial design was used to evaluate the effects of treatment variables, that is, temperature (50 to 90 °C), time (1 to 29 min), and pH (2 to 8), on the residual antifungal activity (RAA) against Penicillium chrysogenum, Fusarium graminearum, Aspergillus flavus, and a Penicillium sp. isolated from moldy noodles. Regression analyses suggested that the linear terms of the temperature and time had significant (P < 0.05) negative effects on the RAA against all test fungi, whereas that of pH had a significant (P < 0.1) positive role on the RAA of all 3 fungi. In addition, the RAA was significantly (P < 0.05) affected by the quadratic terms of time for all fungi, and the quadratic term of temperature played a significant (P < 0.1) role on RAA against F. graminearum. One interaction term (temperature-pH) was found to significantly (P < 0.1) affect the RAA against both Penicillium strains tested. The results indicated that , 90% antifungal activity was lost after the protein extracts were heated at 90 °C for 8 min except for F. graminearum. At pasteurization condition, , 50% activity was retained except for P. chrysogenum. The results also suggested that neutral and alkaline pH favored the antifungal activity stability of the protein extracts. Thus, flaxseed protein might be promising if used as a preservative in foods with neutral or alkaline pH requiring mild heat treatments. [source] Nosocomial bloodstream infections associated with Candida species in a Turkish University HospitalMYCOSES, Issue 2 2006Nur Yapar Summary In recent years, a progressive increase in the frequency of nosocomial candidaemia has been observed, especially among the critically ill or immunocompromised patients. The aim of this study was to evaluate the trend in incidence of candidaemia together with potential risk factors in an 850-bed Turkish Tertiary Care Hospital in a 4-year period. A total of 104 candidaemia episodes were identified in 104 patients. The overall incidence was 0.56 per 1000 hospital admissions and the increase in incidence of candidaemia from 2000 to 2003 was found to be statistically significant (P = 0.010). Candida albicans was the most common species (57.7%) and non- albicans species accounted for 42.3% of all episodes. The most common non- albicans Candida sp. isolated was C. tropicalis (20.2%) followed by C. parapsilosis (12.5%). The most frequent risk factors possibly associated with the candidaemia were previous antibiotic treatment (76.9%), presence of central venous catheter (71.2%) and total parenteral nutrition (55.8%). Our results show the fact that the incidence of candidaemia caused by non- albicans species is frequent and increasing significantly, although the most common isolated Candida species were C. albicans and further investigations are necessary to evaluate the mechanisms of increasing incidence of candidaemia caused by non- albicans species. [source] Photodegradation of Soil Organic Matter and its Effect on Gram-negative Bacterial GrowthPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 5 2008Gabriela N. Bosio ABSTRACT To learn more about the role of the reactive oxygen species (ROS) in the production of bioavailable products of the dissolved organic matter, we investigate here the effect of the photolysis (,exc > 320 nm) of a soil extract (SE) on the growth of bacteria isolated from the same soil as used for obtaining the extract. Comparative experiments with Aldrich humic acid (AHA) as substrate were performed. The photodegradation of the SE was evaluated with different techniques,UV,visible absorption spectroscopy, fluorescence excitation emission matrices (EEM) and Fourier transform infrared spectroscopy (FTIR). Known ROS scavengers were employed to study the effect of photochemically produced ROS on the photodegradation of the substrates. To evaluate the effect of irradiation on the bioavailability of the SE and AHA, photolyzed and nonphotolyzed substrates were added to different culture media and the growth of Pseudomonas sp. isolated from the soil and a strain of Escherichia coli were studied. The different results obtained were assigned to the dissimilar metabolisms of both bacteria. [source] Proteomic analysis of the response of an acidophilic strain of Chlamydomonas sp. (Chlorophyta) to natural metal-rich waterPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 10 2010Cristina Cid Abstract A proteomic approach including 2-DE and MALDI-TOF analysis has been developed to identify the soluble proteins of the unicellular photosynthetic algae Chlamydomonas sp. isolated from an extreme acidic environment, Río Tinto (southwest Spain). We have analyzed the soluble proteome obtained from whole cells growing on metal-rich natural acidic water from the river in comparison with the same strain growing in artificial BG-11 media. The most drastic effect was the decrease in the abundance of the ribulose-1,5-biphosphate carboxylase as well as other enzymes related to photosynthesis. However, phytochrome B, phosphoribulokinase, and phosphoglycerate kinase were upregulated when cells were grown in metal-rich acidic water. Besides, increased accumulation of two Hsps, Hsp70 and Hsp90 as well as other stress-related enzymes were also found in the cells growing in natural acidic water. These results suggest that naturally occurring metal-rich water induces a stress response in acidophilic Chlamydomonas forcing algal cells to reorganize their metabolic pathways as an adaptive response to these environmental conditions. [source] A Marine Dinoflagellate, Amphidinium eilatiensis n. sp., from the Benthos of a Mariculture Sedimentation Pond in Eilat, IsraelTHE JOURNAL OF EUKARYOTIC MICROBIOLOGY, Issue 6 2003JOHN J. LEE ABSTRACT. A species of Amphidinium bloomed in a mariculture sedimentation pond that was used to grow bivalves near the Gulf of Eilat, Israel. Its overall length averaged 13 ,m, the hypocone was 11 ,m, and its width was 8,m. It has a ventral ridge. The sulcus begins at the longitudinal flagellar pore and does not project forward in the apex toward the transverse flagellar pore and left margin of the cingulum. The sulcus is a very shallow groove that projects variably about a third of the body length toward the antapex. The cingulum is a deep groove as it circles the cell from the left ventral side to the dorsal side and then becomes very shallow on the right ventral side as it arches posterior toward the longitudinal flagellar pore. Using a modified method for studying dinoflagellate chromosomes in the SEM, we observed 31 chromosomes. The plastid is dorsal and peripheral with 6 ventrally projecting peripheral digital lobes that wrap around the sides of the ventral and posterior nucleus. Amphidinium eilatiensis n. sp. is morphologically closest to Amphidinium carterae and Amphidinium rhynchocephalum, but it does not have the obvious thecal plates or polygonal units described for the former species. Instead, it has a series of spicules, bumps, and ridges on its surface. It differs from A. rhynchocephalum by two morphological characters: surface morphology and gross plastid architecture. The amplified fragments of the rDNA from A. eilatiensis n. sp. isolated from 2 separate sedimentation ponds in Eilat include the 3,-end of the SSU rDNA (about 100 nt), the whole ITS region (ITS1 + 5. 8S + ITS2) and the 5,-end of the LSU rDNA (about 900 nts). The total length of the sequences ranged from 1,460 nt. (A. eilatiensis isolate #1) to 1,461 nts. (A. eilatiensis isolate #2). The latter sequences are identical, the difference in length being due to three insertions. Amphidinium eilatiensis is genetically more closely related to A. carterae than to A. klebsii, with respectively 2. 36% and 6. 93% of sequence divergence. [source] Characterization of electrochemical activity of a strain ISO2-3 phylogenetically related to Aeromonas sp. isolated from a glucose-fed microbial fuel cellBIOTECHNOLOGY & BIOENGINEERING, Issue 5 2009Kyungmi Chung Abstract The microbial communities associated with electrodes in closed and open circuit microbial fuel cells (MFCs) fed with glucose were analyzed by 16S rRNA approach and compared. The comparison revealed that bacteria affiliated with the Aeromonas sp. within the Gammaproteobacteria constituted the major population in the closed circuit MFC (harvesting electricity) and considered to play important roles in current generation. We, therefore, attempted to isolate the dominant bacteria from the anode biofilm, successfully isolated a Fe (III)-reducing bacterium phylogenetically related to Aeromonas sp. and designated as strain ISO2-3. The isolated strain ISO2-3 could grow and concomitantly produce current (max. 0.24,A/m2) via oxidation of glucose or hydrogen with an electrode serving as the sole electron acceptor. The strain could ferment glucose, but generate less electrical current. Cyclic voltammetry supported the strain ISO2-3 was electrically active and likely to transfer electrons to the electrode though membrane-associated compounds (most likely c-type cytochrome). This mechanism requires intimate contact with the anode surface. Scanning electron microscopy revealed that the strain ISO2-3 developed multiplayer biofilms on the anode surface and also produced anchor-like filamentous appendages (most likely pili) that may promote long-range electron transport across the thick biofilm. Biotechnol. Bioeng. 2009; 104: 901,910. © 2009 Wiley Periodicals, Inc. [source] | |||||||||||||