Activity Of Lac Research Articles

Ligninolytic enzyme potential of Trametes spp. associated with leaf litter in riparian forest of the Amazônia region.

The present study explored the potential of leaf litter as a source of fungi able to produce ligninolytic enzymes for the biodegradation of anthraquinone dyes. Within the colonies isolated from the leaf litter, only three colonies of two species Trametes were selected based on the detection of oxidation and decolorization halos in Petri dishes with PDA (potato-dextrose-agar) + Guaicol and PDA + RBBR (Remazol Brilliant Blue R). The identification of the colonies was done through sequencing of the ITS region. The enzymatic activity of Lac (lacase), MnP (manganês peroxidase) and LiP (lignina peroxidase) was analyzed by spectrophotometry during fermentation in PD+RBBR imedium. Isolates A1SSI01 and A1SSI02 were identified as Trametes flavida, while A5SS01 was identified as Trametes sp. Laccase showed the highest enzymatic activity, reaching 452.13 IU.L-1 (A1SSI01, 0.05% RBBR) after 96h. Isolate A1SSI02 reached the highest percentage of decolorization, achieving 89.28% in seven days. The results imply that these Trametes isolates can be highly effective in waste treatment systems containing toxic anthraquinone dyes. Keywords: laccase, peroxidases, basidiomycete, litter and biodecolorization.

Investigation of the Flaring Activity of BL Lac in July–November 2021

Investigation of the Flaring Activity of BL Lac in July–November 2021

Enhanced lignin biodegradation by consortium of white rot fungi: microbial synergistic effects and product mapping

BackgroundAs one of the major components of lignocellulosic biomass, lignin has been considered as the most abundant renewable aromatic feedstock in the world. Comparing with thermal or catalytic strategies for lignin degradation, biological conversion is a promising approach featuring with mild conditions and diversity, and has received great attention nowadays.ResultsIn this study, a consortium of white rot fungi composed of Lenzites betulina and Trametes versicolor was employed to enhance the ligninolytic enzyme activity of laccase (Lac) and manganese peroxidase (MnP) under microbial synergism. The maximum enzymatic activity of Lac and MnP was individually 18.06 U mL−1 and 13.58 U mL−1 along with a lignin degradation rate of 50% (wt/wt), which were achieved from batch cultivation of the consortium. The activities of Lac and MnP obtained from the consortium were both improved more than 40%, as compared with monocultures of L. betulina or T. versicolor under the same culture condition. The enhanced biodegradation performance was in accordance with the results observed from scanning electron microscope (SEM) of lignin samples before and after biodegradation, and secondary-ion mass spectrometry (SIMS). Finally, the analysis of heteronuclear single quantum coherence (HSQC) NMR and gas chromatography–mass spectrometry (GC–MS) provided a comprehensive product mapping of the lignin biodegradation, suggesting that the lignin has undergone depolymerization of the macromolecules, side-chain cleavage, and aromatic ring-opening reactions.ConclusionsOur results revealed a considerable escalation on the enzymatic activity obtained in a short period from the cultivation of the L. betulina or T. versicolor due to the enhanced microbial synergistic effects, providing a potential bioconversion route for lignin utilization.

Acoplamiento molecular de oxidasas de Pleurotus ostreatus y la actividad de estas producidas por la cepa ARS 3526 crecida tanto en fermentación sumergida como fermentación en estado sólido

Pleurotus ostreatus is a basidiomycete fungus capable of producing oxidases involved in the degradation of lignin, such as laccase (Lac), manganese peroxidase (MnP), versatile peroxidase (VP), veratryl alcohol oxidase (VAO) and dye-decolorizing peroxidase (DyP). In this research, the molecular docking showed that the interaction between Mn-ion, ABTS or DMP ligand with the respective oxidases studied were strongly supported by exposed GLU and ASP charged residues H-bonded or hydrophobic-bonded, in most of the complexes, mainly GLU and ASP played a very important role in the union, especially in the presence of the Mn-ion. On the other hand, the growth and activity of such enzymes of Pleurotus ostreatus ARS 3526 grown in both, submerged fermentation (SmF) and solid-state fermentation (SSF) were evaluated. The specific growth rate in SSF was 2.5 times higher than in SmF. The values of activity of Lac, VP and DyP were higher in the SSF, of the VAO activity was similar in both fermentation systems and SmF had the higher MnP activity value in comparison with SSF. This study provides evidence of the enzymatic potential of this fungus and shows the similarities in charged amino acids when used in their catalytic interactions, and the intimate relationship between the enzyme and its substrate.

Evaluation of bezafibrate, gemfibrozil, indomethacin, sulfamethoxazole, and diclofenac removal by ligninolytic enzymes

The laccase (Lac), manganese peroxidases (MnP), and lignin peroxidase enzymes produced by basidiomycete have been studied due to their potential in bioremediation, therefore, in this study, degradation of diclofenac (DCF), sulfamethoxazole (SMX), indomethacin (IND), gemfibrozil (GFB), and bezafibrate (BZF) by enzymes produced by Trametes maxima, Pleurotus sp., and Pycnosporus sanguineus grown in culture was evaluated. The degradation of drugs can mainly be attributed to MnP because a correlation between the activity of this enzyme and the degree of removal was found. The specific activity of Lac did not show correlation with drug removal, while lignin peroxidase was not expressed. Trametes maxima showed the highest specific activity of MnP (387.6 ± 67.4 U/mg) and efficiency removal 90.2% of DCF, 72.62% of SMX, 60.76% of IND, 43.39% of GFB, and 32.59% of BZF) followed by Pleurotus sp. with specific activity of MnP of 55.9 ± 8.5 U/mg and 89.47% of DCF, 47.61% of GFB and 73% of IND were removed, P. sanguineus had the lowest specific activity of 18 ± 1.3 U/mg and was able to remove only 42% of SMX and 10.59% of IND. In order to prove that MnP remove drugs instead of Lac, the pure Lac was tested and only degraded DCF.

Simultaneous Pretreatment and Biohydrogen Production from Wheat Straw by Newly Isolated Ligninolytic Bacillus Sp. Strains with Two-Stage Batch Fermentation System

Biodegradation of agribiomass especially wheat straw to biohydrogen and biomethane is an encouraging approach to the current waste management problem. To do so, the biomass must first be pretreated to break down lignin thereby increasing accessibility of the substrate to fermentative organisms. In the current study, out of 20 isolates from the granular sludge of full-scale anaerobic digester, four ligninolytic Bacillus sp. strains were selected based on their lignin and Azure B degradation. Further, among the four isolates, Brevibacillus agri AN-3 exhibited the highest of 88.4 and 78.1% decrease in COD of lignin and Azure B respectively. These strains were also found to secrete optimum yields of lignin peroxidase (LiP) at pH 3, laccase (Lac) at pH 5, and xylanase and cellulase enzymes at pH 7. The strains demonstrated maximum activity of Lip and Lac at 50 °C and xylanase and cellulase at 60 °C after 72-h growth. Among the four strains, Brevibacillus agri AN-3 showed hydrogen (H2) yield of 1.34 and 2.9 mol-H2/mol from xylose and cellulose respectively. In two-phase wheat straw batch fermentation, Brevibacillus agri AN-3 produced 88.3 and 283.7 mL/gVS cumulative H2 and methane (CH4) respectively. Biotreatment with ligninolytic Bacillus sp. strains perceived that 261.4% more methane yield could be obtained from the wheat straw than using the untreated wheat straw in batch fermentation. This is the first study establishing not only the hydrogen potential of ligninolytic Bacillus sp. strains but also indicates a vital role of these species in developing standard inoculum and a biocatalyst for processing agribiomass.

Critical Temperature of 1-Palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine Monolayers and Its Possible Biological Relevance.

Because transmembrane proteins (TMPs) can be obtained with sufficient purity for X-ray diffraction studies more frequently than decades ago, their mechanisms of action may now be elucidated. One of the pending issues is the actual interplay between transmembrane proteins and membrane lipids. There is strong evidence of the involvement of specific lipids with some membrane proteins, such as the potassium crystallographically sited activation channel (KcsA) of Streptomyces lividans and the secondary transporter of lactose LacY of Escherichia coli, the activities of which are associated with the presence of anionic phospholipids such as the phosphatidylglycerol (PG) and phosphatidyethanolamine (PE), respectively. Other proteins such as the large conductance mechanosensitive channel (MscL) of E. coli seem to depend on the adaptation of specific phospholipids to the irregular surface of the integral membrane protein. In this work we investigated the lateral compressibility of two homoacid phosphatidylethanolamines (one with both acyl chains unsaturated (DOPE), the other with the acyl chains saturated (DPPE)) and the heteroacid phosphatidyletanolamine (POPE) and their mixtures with POPG. The liquid expanded (LE) to liquid condensed (LC) transition was observed in POPE at a temperature below its critical temperature (Tc = 36 °C). Because Tc lies below the physiological temperature, the occurrence of this phase transition may have something to do with the functioning of LacY. This magnitude is discussed within the context of the experiments carried out at temperatures below the Tc of POPE at which the activity of Lac Y and other TMPs are frequently studied.

Catalytic potential of laccase immobilized on transition metal oxides nanomaterials: Degradation of alizarin red S dye

Recently, nanoparticle-based immobilization of biocatalytic systems is getting interested in bioremediation efficiency. Therefore, green synthesized ZnO (<50nm) and MnO2 (<10nm) nanoparticles were chelated with Cu2+ to immobilize laccase (Lac) through metal affinity adsorption. Nanospheres (∼300nm) of lac-ZnO and nanoclusters of lac-MnO2(<50nm) were confirmed by SEM. Lac was strongly immobilized on ZnO followed by MnO2 and their activities were doubled than free lac prepared by solid state fermentation. Further, catalytic potential of lac-ZnO and lac-MnO2 was examined for in vitro degradation of alizarin red S dye in simulated-water. Degradation of dye was highest with lac-ZnO (95%) followed by lac-MnO2 (85%) and free lac (49%) at initial pH (∼7.0), dye (20mg/L) and catalyst (50mg). Control experiment indicated that lac-ZnO was the better catalyst than ZnO and free lac. MnO2 seemed to enhance stability and activity of lac- MnO2 over free lac. Moreover, a combination of nanomaterial and enzyme is required for achieving biocompatibility and inert condition without denaturing of the enzyme. Overall, ZnO and MnO2 are potential for large-scale lac immobilization with improved properties and reuse. Lac-ZnO and lac-MnO2 may be used as important adsorbents in waste water treatment with a bright future.

Probiotic Properties of Lactobacillus fermentum Strains Isolated from Human Oral Samples and Description of their Antibacterial Activity.

Gram positive bacteria produce peptides, defined bacteriocins which exhibit good antibacterial activity. We evaluated the ability of L. fermentum to produce bacteriocins having therefore, good probiotic features and finally, be safe towards microglial cells. Eight wild strains, identified using molecular techniques, were investigated for the evaluation of resistance to bile salts, low pH, H2O2 production, biofilm formation, antibacterial activity and safety on microglia cells (BV2). The determination of the susceptibility/resistance profile showed that the strains are sensitive to the antibiotics tested. All strains showed a good tolerability to extremely low pH as well as resisting in presence of bile salts. In addition, the strains showed excellent activity against pathogens and one of them (LAC 42) showed activity also against Pseudomonas aeruginosa and Klebsiella pneumoniae. Finally, LAC 42 and its active compound did not change microglia cell viability following 24h exposure. Our data on this antibacterial molecule suggest that it is a compound with low molecular weight and with highly hydrophilic component. These results describe the characteristics of Lactobacillus strains and provide evidences for their possible use as new potential probiotic. In addition, other studies are now warranted to exploit the antibacterial activity of the supernatant LAC 42 and for its complete chemical characterization.

Properties of Laccases Produced by Pycnoporus sanguineus Induced by 2,5-xylidine

Two isoforms of laccase produced from the culture supernatant of Pycnoporus sanguineus were partially purified by phenyl-Sepharose chromatography. Molecular masses of the enzymes were 80 kDa (Lac I) and 68 kDa (Lac II). Optimum activity of Lac I was at pH 4.8 and 30 degrees C, and Lac II was at pH 4.2 and 50 degrees C over 5 min reaction. The Km values of enzymes toward syringaldazine were 10 microM: (Lac I) and 8 microM: (Lac II). Sodium azide inhibited Lac I (85%) and Lac II (75%) activities.

A Photometric Study of the Activity of Sw Lac

A Photometric Study of the Activity of Sw Lac

Interactions between propionic acid bacteria and thermophilic lactic acid bacteria

The growth of propionic acid bacteria was directly dependent on the concentration of free amino acids in cheese, regardless of the strains of lactobacilli contained in the raw mixed cultures, suggesting that the growth of these bacteria was mainly dependent on the proteolytic activity of lac- tic acid bacteria. The stimulating effect of S. thermophilus was poor probably because this species pro- duces only low amounts of amino acids in milk or cheese. Lactobacilli, which undergo cell Iysis shortly after cheese manufacture, produce large amounts of amino acids. Facultatively heterofer- mentative lactobacilli were shown to reduce the risk of secondary fermentation in Emmental cheese. This interaction was not due to their production of diacetyl, formate or acetate. Propionibacteria able to grow at 14 C have a greater tendency to induce secondary fermentation compared to those unable to grow at this temperature. © InralElsevier, Paris. propionic acid bacteria / lactic acid bacteria / facultatively heterofermentative Iactobacilli / interaction / secondary fermentation

Formaldehyde as a Proof and Response to Various Kind of Stress in Some Basidiomycetes

The influence of cadmium chloride and/or high temperature on the level of selected parameters were examined in both medium and mycelium of some Basidiomycetes belonging to white-rot fungi: Abortiporus biennis, Trametes versicolor and Cerrena unicolor. We investigated changes in the formaldehyde (FA) level and in the level of superoxide radical anions (SR). Accordingly, the capacity of three enzymes was also studied: two enzymes of the cellular antioxidative system - superoxide dismutase (SOD; EC 1.15.1.1), and catalase (CAT; EC 1.11.1.6), and laccase (LAC; EC 1.10.3.2) the main lignin-modifying enzyme, which is produced by white-rot fungi. During the first 24 hours after application of separate stressors, or jointly with two stressors to 10-day-old cultivation, changes in all selected parameters were observed. Moreover, we found significant changes in the levels of extracellular SR, FA and extra- and intracellular activity of LAC. Simultaneous action of two stressors in the fungal cultures decreased the extracellular LAC level, intracellular CAT activity and the level of SR in the medium compared to the control values, while using the two stress factors separately would strongly make these values increase. Stressful conditions brought a rapid increase in the level of FA in all fungal species. The results of our study, carried out on selected strains of Basidiomycetes, seem to have shown that: (I) LAC, the lignin-modifying enzyme, may have an important application in fungal stress response, and take part in the cross-protection between responses to heat shock and cadmium resistance; (2) the oxidative burst as a result of cadmium and high temperature treatment is an additional factor to damage fungal cells; (3) FA may be a determining factor in the phases of fungal stress syndrome.

Photometric Research of Pre-flare and Extra-flare Activity of Flare Stars

Preliminary results of a photometric search for non-flare activity of the flare star EV Lac during June-August 1994 are presented. These observations are part of the long-term project entitled “Investigation of pre-flare processes on flare stars” being carried out at the Observatory of the Jordan Valley Regional College since July 1994. The project was motivated by reports of the existence of slow, low-amplitude non-periodic variability of both spectral lines and continuum outside/between flares (Rodono et al. 1979, Roizman et al. 1984).

Short-Time Flare Events of EV Lac

Moffett (1972) pointed out the existence of short-time outbursts in flare stars as long ago as 1972. Gershberg &amp; Petrov (1986) had registered a flare in EV Lac with a duration of 28.4 and an amplitude of 38.4 in 1984 with ASTRON. In recent years, a few reports appeared about observations of short-time outbursts in EV Lac with a duration in the range from 08.1 to several seconds. These results were summarized briefly by Zhilyaev (1993). Our observations confirm the existence of short-time flare activity on EV Lac.The observations reported here were obtained at the 60 cm telescope at the Peak Terskol high-altitude Observatory (3 100 m above sea level) with a highspeed two-channel photometer (Zhilyaev et al. 1992) in B as well as simultaneously in both, U and V bands, with a time resolution down to 08.1. A new prefiltering technique (Zhilyaev 1995) has been used for the detection of smallscale activity of the flare star EV Lac.

Diversity in genetic instability of lactose fermentation and proteinase production among lactic streptococci.

In this study, we used several lactic streptococcal strains and examined as to whether or not there is a difference in the stability of lactose metabolism among strains or species, because we found its apparent stability in S. cremoris H-61, compared with in S. lactis. Additionally, we investigated the genetic linkage of lactose metabolism and proteinase production through examination of the proteolytic activity of Lac − variants

Compartmented pyruvate in perfused working heart

Pyruvate compartmentation and lactate dehydrogenase (LDH) were studied in isolated perfused working guinea pig hearts. The mean intracellular pyruvate (Pyr) contents increased with perfusate Pyr (0-2 mM) but varied only slightly with glucose (0-10 mM) and additional insulin (0.04-5 U/l), respectively. With 5-10 mM glucose plus 5 U/l insulin, but not with Pyr or lactate (Lac) as substrates, a near equilibrium between the LDH and the glycerol-3-phosphate dehydrogenase seemed to exist. Evidence for an inhibitory effect of Pyr on the activity of the LDH system of the perfused hearts was not obtained. With [U-14C]glucose as sole substrate, the specific activity of coronary venous Lac was near half that of precursor glucose. 14CO2 production was thus in quantitative agreement with rates of pyruvate oxidation that were determined as glucose uptake minus (Pyr + Lac) release. In contrast, with 0.2 mM [1-14C]Pyr plus 5 mM glucose, the ratio of 14CO2 production to specific activity of Lac overestimated Pyr oxidation judged from myocardial substrate balances and O2 uptake, respectively; here, at least three pools of [14C]HCO-3 and [14C]lac, respectively, were kinetically demonstrable during washout of trace amounts of 14C-labeled Pyr. Evidently, the specific activity of Lac was equivalent to that of mitochondrial oxidized Pyr provided [14C]glucose was the sole or major precursor of cellular pyruvate. However, exogenously applied [1-14C]Pyr of high specific activity seemed to induce intracellular formation of both a highly and lowly labeled Pyr; the latter Pyr compartment did not seem in ready equilibrium with the cell physiologically prevailing highly labeled Pyr pool.

CONTROL OF GLUCONEOGENESIS IN THE BABOON FETUS

Regulation of gluconeogenesis has been studied in 4 baboon fetuses (135-140 d.) with catheters chronically placed in the inferior vena cava and aorta, using a single isotope-labeled precursor technique. A primed infusion of [u-14C] lactate (Lac) was administered to the fetus to steady state over 150 min. Net Lac to glucose (Glu) conversion was evaluated by comparing fetal (Fet) and Maternal (Mat) dpm and specific activity (S.A.) of Lac and Glu during Mat fed (4), fasting (4), and Glu infusion (1) (Iglu). Mat/Fet Glu dpm were 36.0±1.9% fed, 51.4±3.1% fasting (p<.001) and 9.2% during Iglu. Mat/Fet Glu S.A. was 27.6±2.4% fed, 44.7±5.2% fasting (p<.001) and 9.5% during Iglu. Fet to Mat placental transfer of Glu and Lac is more efficient in the baboon than in the sheep, but higher Fet than Mat 14C Glu enrichment confirms the capacity of the primate fetus for gluconeogenesis. Fet gluconeogenesis from Lac is regulated by Mat nutrient status and substrate supply.