Immobilization and stabilization of microbial lipases by multipoint covalent attachment on aldehyde-resin affinity: Application of the biocatalysts in biodiesel synthesis

Microbial lipase preparations from Thermomyces lanuginosus (TLL) and Pseudomonas fluorescens (PFL) were immobilized by multipoint covalent attachment on Toyopearl AF-amino-650M resin and the most active and thermal stable derivatives used to catalyze the transesterificanon reaction of babassu and palm oils with ethanol in solvent-free media For this different activating agents mainly glutaraldehyde glycidol and epichlorohydrin were used and immobilization parameters were estimated based on the hydrolysis of olive oil emulsion and butyl butyrate synthesis ILL immobilized on glyoxyl-resin allowed obtaining derivatives with the highest hydrolytic activity (HA(der)) and thermal stability between 27 and 31 times more stable than the soluble lipase Although PFL derivatives were found to be less active and thermally stables similar formation of butyl butyrate concentrations were found for both ILL and PFL derivatives The highest conversion into biodiesel was found in the transesterification of palm oil catalyzed by both ILL and PFL glyoxyl-derivatives (c) 2010 Elsevier B V All rights reserved

Fermentative hydrogen production by microbial consortium

Heat pre-treatment of the inoculum associated to the pH control was applied to select hydrogen-producing bacteria and endospores-forming bacteria. The source of inoculum to the heat pre-treatment was from a UASB reactor used in the slaughterhouse waste treatment. The molecular biology analyses indicated that the microbial consortium presented microorganisms affiliated with Enterobacter cloacae (97% and 98%), Clostridium sp. (98%) and Clostridium acetobutyricum (96%), recognized as H, and volatile acids` producers. The following assays were carried out in batch reactors in order to verify the efficiencies of sucrose conversion to H-2 by the microbial consortium: (1) 630.0 mg sucrose/L, (2) 1184.0 mg sucrose/L, (3) 1816.0 mg sucrose/L and (4) 4128.0 mg sucrose/L. The subsequent yields were obtained as follows: 15% (1.2 mol H-2/mol sucrose), 20% (1.6 mol H-2/mol sucrose), 15% (1.2 mol H-2/mol sucrose) and 4% (0.3 mol H-2/mol sucrose), respectively. The intermediary products were acetic acid, butyric acid, methanol and ethanol in all of the anaerobic reactors. (C) 2008 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.

Microbial distribution in the root canal system after periapical lesion induction using different methods

The aim of this study was to evaluate the microbial distribution in the root canal system after periapical lesion induction in dogs' teeth using different methods. Fifty-two root canals were assigned to 4 groups (n=13). Groups I and II: root canals were exposed to the oral cavity for 180 days; groups III and IV: root canals were exposed for 7 days and then the coronal openings were sealed for 53 days. The root apices of groups I and III were perforated, while those of groups II and IV remained intact. After the experimental periods, the animals were euthanized and the anatomic pieces containing the roots were processed and stained with the Brown & Brenn method to assess the presence and distribution of microorganisms. The incidence of microorganisms at different sites of the roots and periapical lesions was analyzed statistically by the chi-square test at 5% significance level. All groups presented microorganisms in the entire root canal system. A larger number of microorganisms was observed on the root canal walls, apical delta and dentinal tubules (p<0.05), followed by cementum and cemental resorption areas. In spite of the different periods of exposure to the oral environment, the methods used for induction of periapical periodontitis yielded similar distribution of microorganisms in the root canal system.

Anticariogenic Properties of ent-Pimarane Diterpenes Obtained by Microbial Transformation

In the present work, the anticariogenic activities of three pimarane-type diterpenes obtained by fungal biotransformation were investigated. Among these metabolites, ent-8(14), 15-pimaradien-19-ol was the most active compound, displaying very promising MIC values (ranging from 1.5 to 4.0 mu g mL(-1)) against the main microorganisms responsible for dental caries: Streptococcus salivarius, S. sobrinus, S. mutans, S. mitis, S. sanguinis, and Lactobacillus casei. Time kill assays performed with ent-8(14), 15-pimaradien-19-ol against the primary causative agent S. mutans revealed that this compound only avoids growth of the inoculum in the first 12 h (bacteriostatic effect). However, its bactericidal effect is clearly noted thereafter (between 12 and 24 h). The curve profile obtained by combining ent-8(14), 15-pimaradien-19-ol and chlorhexidine revealed a significant reduction in the time necessary for killing S. mutans compared with each of these two chemicals alone. However, no synergistic effect was observed using the same combination in the checkerboard assays against this microorganism. In conclusion, our results point out that ent-8(14), 15-pimaradien-19-ol is an important metabolite in the search for new effective anticariogenic agents.

The conversion of phase to amplitude fluctuations of a light beam by an optical cavity

Very low intensity and phase fluctuations are present in a bright light field such as a laser beam. These subtle quantum fluctuations may be used to encode quantum information. Although intensity is easily measured with common photodetectors, accessing the phase information requires interference experiments. We introduce one such technique, the rotation of the noise ellipse of light, which employs an optical cavity to achieve the conversion of phase to intensity fluctuations. We describe the quantum noise of light and how it can be manipulated by employing an optical resonance technique and compare it to similar techniques, such as Pound - Drever - Hall laser stabilization and homodyne detection. (c) 2008 American Association of Physics Teachers.

Chemiluminescence-based uphill energy conversion

The conversion of red excitation light into blue emission light (uphill energy conversion) using unstable 1,2-dioxetanes is described. The method is based on 1,2-dioxetane formation by red-light sensitized photooxygenation of adequate alkenes and subsequent blue-light emission due to thermal 1,2-dioxetane cleavage. The energy gain resulting from the chemical energy obtained in the transformation of an alkene into two carbonyl compounds transforms a red-light excitation laser beam into a blue-light chemiluminescence emission, producing thereby a formal anti-Stokes shift of 200-250 nm, opening up a whole spectrum of possible applications.

Conversion to soy on the Amazonian agricultural frontier increases streamflow without affecting stormflow dynamics

Large-scale soy agriculture in the southern Brazilian Amazon now rivals deforestation for pasture as the region`s predominant form of land use change. Such landscape-level change can have substantial consequences for local and regional hydrology, but these effects remain relatively unstudied in this ecologically and economically important region. We examined how the conversion to soy agriculture influences water balances and stormflows using stream discharge (water yields) and the timing of discharge (stream hydrographs) in small (2.5-13.5 km2) forested and soy headwater watersheds in the Upper Xingu Watershed in the state of Mato Grosso, Brazil. We monitored water yield for 1 year in three forested and four soy watersheds. Mean daily water yields were approximately four times higher in soy than forested watersheds, and soy watersheds showed greater seasonal variability in discharge. The contribution of stormflows to annual streamflow in all streams was low (< 13% of annual streamflow), and the contribution of stormflow to streamflow did not differ between land uses. If the increases in water yield observed in this study are typical, landscape-scale conversion to soy substantially alters water-balance, potentially altering the regional hydrology over large areas of the southern Amazon.

Effect of hemicellulose and lignin on enzymatic hydrolysis of cellulose from brewer`s spent grain

Enzymatic hydrolysis of brewer`s spent grain in three different forms: original (untreated), pretreated by dilute acid (cellulignin), and pretreated by a sequence of dilute acid and dilute alkali (cellulose pulp), was studied to verify the effect of hemicellulose and lignin on cellulose conversion into glucose. The hydrolysis was carried out using a commercial cellulase concentrate (Celluclast 1.5 L) in an enzyme/substrate ratio of 45 FPU/g, 2% (w/v) substrate concentration, 45 degrees C for 96 h. According to the results, the cellulose hydrolysis was affected by the presence of hemicellulose and/or lignin in the sample. The cellulose conversion ratio (defined as glucose yield + cellobiose yield) from cellulignin was 3.5-times higher than that from untreated sample, whereas from cellulose pulp such value was 4-times higher, correspondent to 91.8% (glucose yield of 85.6%). This best result was probably due to the strong modification in the material structure caused by the hemicellulose and lignin removal from the sample. As a consequence, the cellulose fibers were separated being more susceptible to the enzymatic attack. It was concluded that the lower the hemicellulose and lignin contents in the sample, the higher the efficiency of cellulose hydrolysis. (C) 2007 Elsevier Inc. All rights reserved.

Contribution of Tris Buffer on Xylitol Enzymatic Production

Xylitol enzymatic production can be an alternative to chemical and microbial processes, because of advantages like higher conversion efficiency. However, for an adequate conversion, it is necessary to investigate the effect of many parameters, such as buffer initial concentration, pH, temperature, agitation, etc. In this context, the objective of this work was to evaluate xylitol enzymatic production under different Tris buffer initial concentrations in order to determine the best condition for this parameter to begin the reaction. The best results were obtained when Tris buffer initial concentration was 0.22 M, reaching 0.31 g L(-1) h(-1) xylitol volumetric productivity with 99% xylose-xylitol conversion efficiency. Although the increase in buffer concentration allowed better pH maintenance, it hindered the catalysis. The results demonstrate that this bioreaction is greatly influenced by involved ions concentrations.

Anaerobic degradation of linear alkylbenzene sulfonate (LAS) in fluidized bed reactor by microbial consortia in different support materials

Four anaerobic fluidized bed reactors filled with activated carbon (R1), expanded clay (R2), glass beads (R3) and sand (R4) were tested for anaerobic degradation of LAS. All reactors were inoculated with sludge from a UASB reactor treating swine wastewater and were fed with a synthetic substrate supplemented with approximately 20 mg l(-1) of LAS, on average. To 560 mg l(-1) COD influent, the maximum COD and LAS removal efficiencies were mean values of 97 +/- 2% and 99 +/- 2%, respectively, to all reactors demonstrating the potential applicability of this reactor configuration for treating LAS. The reactors were kept at 30 degrees C and operated with a hydraulic retention time (HRT) of 18 h. The use of glass beads and sand appear attractive because they favor the development of biofilms capable of supporting LAS degradation. Subsequent 16S rRNA gene sequencing and phylogenetic analysis of samples from reactors R3 and R4 revealed that these reactors gave rise to broad microbial diversity, with microorganisms belonging to the phyla Bacteroidetes, Firmicutes, Actinobacteria and Proteobacteria, indicating the role of microbial consortia in degrading the surfactant LAS. (C) 2010 Elsevier Ltd. All rights reserved.

Microbial processes and bacterial populations associated to anaerobic treatment of sulfate-rich wastewater

A pilot-scale (1.2 m(3)) anaerobic sequencing batch biofilm reactor (ASBBR) containing mineral coal for biomass attachment was fed with sulfate-rich wastewater at increasing sulfate concentrations. Ethanol was used as the main organic source. Tested COD/sulfate ratios were of 1.8 and 1.5 for sulfate loading rates of 0.65-1.90 kgSO(4)(2-)/cycle (48 h-cycle) or of 1.0 in the trial with 3.0 gSO(4)(2-) l(-1). Sulfate removal efficiencies observed in all trials were as high as 99%. Molecular inventories indicated a shift on the microbial composition and a decrease on species diversity with the increase of sulfate concentration. Beta-proteobacteria species affiliated with Aminomonas spp. and Thermanaerovibrio spp. predominated at 1.0 gSO(4)(2-) l(-1). At higher sulfate concentrations the predominant bacterial group was Delta-proteobacteria mainly Desulfovibrio spp. and Desulfomicrobium spp. at 2.0 gSO(4)(2-) l(-1), whereas Desulfurella spp. and Coprothermobacter spp. predominated at 3.0 gSO(4)(2-) l(-1). These organisms have been commonly associated with sulfate reduction producing acetate, sulfide and sulfur. Methanogenic archaea(Methanosaeta spp.)was found at 1.0 and 2.0 gSO(4)(2-) l(-1). Additionally, a simplified mathematical model was used to infer on metabolic pathways of the biomass involved in sulfate reduction. (C) 2009 Elsevier Ltd. All rights reserved.

Performance of a horizontal-flow anaerobic immobilized biomass (HAIB) reactor and dynamics of the microbial community during degradation of pentachlorophenol (PCP)

The anaerobic biological treatment of pentachlorophenol (PCP) and methanol as the main carbon source was investigated in a horizontal-flow anaerobic immobilized biomass (HAIB) reactor at 30 +/- 1 degrees C, during a 220-day trial period. The reactor biomass was developed as an attached biofilm on polyurethane foam particles, with 24 h of hydraulic retention time. The PCP concentrations, which ranged from 2.0 to 13.0 mg/L, were controlled by adding synthetic substrate. The HAIB reactor reduced 97% of COD and removed 99% of PCP. The microbial biofilm communities of the HAIB reactor amended with PCP, without previous acclimatization, were characterized by polymerase chain reaction (PCR) and amplified ribosomal DNA restriction analysis (ARDRA) with specific Archaea oligonucleotide primers. The ARDRA technique provided an adequate analysis of the community, revealing the profile of the selected population along the reactor. The biomass activities in the HAIB reactor at the end of the experiments indicated the development of PCP degraders and the maintenance of the population of methanogenic Archaea, ensuring the high efficiency of the system treating PCP with added methanol as the cosubstrate. The use of the simplified ARDRA method enabled us to monitor the microbial population with the addition of high concentrations of toxic compounds and highlighting a selection of microorganisms in the biofilm. (C) 2008 Published by Elsevier Ltd.

Evaluation of the microbial diversity in a horizontal-flow anaerobic immobilized biomass reactor treating linear alkylbenzene sulfonate

The purpose of this work was to assess the degradation of linear alkylbenzene sulfonate (LAS) in a horizontal-flow anaerobic immobilized biomass (HAIB) reactor. The reactor was filled with polyurethane foam where the sludge from a sanitary sewage treatment was immobilized. The hydraulic detention time (HDT) used in the experiments was of 12 h. The reactor was fed with synthetic substrate (410 mg l(-1) of meat extract, 115 mg l(-1) of starch, 80 mg l(-1) of saccharose, 320 mg l(-1) of sodium bicarbonate and 5 ml l(-1)of salt solution) in the following stages of operation: SI-synthetic substrate, SII-synthetic substrate with 7 mg l(-1) of LAS, SIII-synthetic substrate with 14 mg l(-1) of LAS and SIV-synthetic substrate containing yeast extract (substituting meat extract) and 14 mg l(-1) of LAS, without starch. At the end of the experiment (313 days) a degradation of similar to 35% of LAS was achieved. The higher the concentration of LAS, the greater the amount of foam for its adsorption. This is necessary because the isotherm of LAS adsorption in the foam is linear for the studied concentrations (2 to 50 mg l(-1)). Microscopic analyses of the biofilm revealed diverse microbial morphologies, while Denaturing Gradient Gel Eletrophoresis (DGGE) profiling showed variations in the population of total bacteria and sulphate-reducing bacteria (SRB). The 16S rRNA gene sequencing and phylogenetic analyses revealed that the members of the order Clostridiales were the major components of the bacterial community in the last reactor operation step.

Long-term stability of hydrogen and organic acids production in an anaerobic fluidized-bed reactor using heat treated anaerobic sludge inoculum

This study evaluates the stability of hydrogen and organic acids production in an anaerobic fluidized-bed reactor (AFBR) that contains expanded clay (2.8-3.35 mm in diameter) as a support medium and is operated on a long-term basis. The reactor was inoculated with thermally pre-treated anaerobic sludge and operated with decreasing hydraulic retention time (HRT), from 8 h to 1 h, at a controlled temperature of 30 degrees C and a pH of about 3.8. Glucose (2000 mg L(-1)) was used as the substrate, generating conversion rates of 92-98%. Decreasing the HRT from 8 h to 1 h led to an increase in average hydrogen-production rates, with a maximum value of 1.28 L h(-1) L(-1) for an HRT of 1 h. In general, hydrogen yield production increased as HRT decreased, reaching 2.29 mol of H(2)/mol glucose at an HRT of 2 h and yielding a maximum hydrogen content of 37% in the biogas. No methane was detected in the biogas throughout the period of operation. The main soluble metabolites (SMP) were acetic acid (46.94-53.84% of SMP) and butyric acid (34.51-42.16% of SMP), with less than 15.49% ethanol. The steady performance of the AFBR may be attributed to adequate thermal treatment of the inoculum, the selection of a suitable support medium for microbial adhesion, and the choice of satisfactory environmental conditions imposed on the system. The results show that stable hydrogen production and organic acids production were maintained in the AFBR over a period of 178 days. (C) 2009 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.

Application of molecular techniques to evaluate the methanogenic archaea and anaerobic bacteria in the presence of oxygen with different COD : sulfate ratios in a UASB reactor

In this paper, the microbial characteristics of the granular sludge in the presence of oxygen (3.0 +/- 0.7 mg O-2 1(-1)) were analyzed using molecular biology techniques. The granules were provided by an upflow anaerobic sludge blanket (UASB) operated over 469 days and fed with synthetic substrate. Ethanol and sulfate were added to obtain different COD/SO42- ratios (3.0, 2.0, and 1.6). The results of fluorescent in situ hybridization (FISH) analyses showed that archaeal cells, detected by the ARC915 probe, accounted for 77%, 84%, and 75% in the COD/SO42- ratios (3.0, 2.0, and 1.6, respectively). Methanosaeta sp. was the predominant acetoclastic archaea observed by optical microscopy and FISH analyses, and confirmed by sequencing of the excised bands of the DGGE gel with a similarity of 96%. The sulfate-reducing bacterium Desulfovibrio vulgaris subsp. vulgaris (similarity of 99%) was verified by sequencing of the DGGE band. Others identified microorganism were similar to Shewanella sp. and Desulfitobacterium hafniense, with similarities of 95% and 99%, respectively. These results confirmed that the presence of oxygen did not severely affect the metabolism of microorganisms that are commonly considered strictly anaerobic. We obtained mean efficiencies of organic matter conversion and sulfate reducing higher than 74%. (C) 2008 Elsevier Ltd. All rights reserved.