Nitrogen-Containing Secondary Metabolites from a Deep-Sea Fungus Aspergillus unguis and Their Anti-Inflammatory Activity.

Aspergillus is well-known as the second-largest contributor of fungal natural products. Based on NMR guided isolation, three nitrogen-containing secondary metabolites, including two new compounds, variotin B (1) and coniosulfide E (2), together with a known compound, unguisin A (3), were isolated from the ethyl acetate (EtOAc) extract of the deep-sea fungus Aspergillus unguis IV17-109. The planar structures of 1 and 2 were elucidated by an extensive analysis of their spectroscopic data (HRESIMS, 1D and 2D NMR). The absolute configuration of 2 was determined by comparison of its optical rotation value with those of the synthesized analogs. Compound 2 is a rare, naturally occurring substance with an unusual cysteinol moiety. Furthermore, 1 showed moderate anti-inflammatory activity with an IC50 value of 20.0 µM. These results revealed that Aspergillus unguis could produce structurally diverse nitrogenous secondary metabolites, which can be used for further studies to find anti-inflammatory leads.

Characterization of the Bacterial Community Associated with Methane and Odor in a Pilot-Scale Landfill Biocover under Moderately Thermophilic Conditions.

A pilot-scale biocover was constructed at a sanitary landfill and the mitigation of methane and odor compounds was compared between the summer and non-summer seasons. The average inlet methane concentrations were 22.0%, 16.3%, and 31.3%, and the outlet concentrations were 0.1%, 0.1%, and 0.2% during winter, spring, and summer, respectively. The odor removal efficiency was 98.0% during summer, compared to 96.6% and 99.6% during winter and spring, respectively. No deterioration in methane and odor removal performance was observed even when the internal temperature of the biocover increased to more than 40°C at midday during summer. During summer, the packing material simultaneously degraded methane and dimethyl sulfide (DMS) under both moderately thermophilic (40-50°C) and mesophilic conditions (30°C). Hyphomicrobium and Brevibacillus, which can degrade methane and DMS at 40°C and 50°C, were isolated. The diversity of the bacterial community in the biocover during summer did not decrease significantly compared to other seasons. The thermophilic environment of the biocover during summer promoted the growth of thermotolerant and thermophilic bacterial populations. In particular, the major methane-oxidizing species were Methylocaldum spp. during summer and Methylobacter spp. during the nonsummer seasons. The performance of the biocover remained stable under moderately thermophilic conditions due to the replacement of the main species and the maintenance of bacterial diversity. The information obtained in this study could be used to design biological processes for methane and odor removal during summer and/or in subtropical countries.

Isolation and identification of putative precursors of the volatile sulfur compounds and their inhibition methods in heat-sterilized melon juices.

Volatile sulfur compounds, such as dimethyl sulfide, dimethyl disulfide and dimethyl trisulfide, cause the off-flavor in heat-sterilized juices and limit the commercial production of juices. In this study, we investigated the precursors for these volatile sulfur compounds and analyzed the potential inhibition methods. Upon separation of melon juice components using resin column, the dimethyl sulfide precursor was present in the acidic fraction whereas the dimethyl trisulfide precursor was present in neutral and acidic fractions. Exogenous addition experiments indicated S-methyl methionine was the precursor of dimethyl sulfide, and methionine was the precursor of dimethyl disulfide and dimethyl trisulfide. The release of volatile sulfur compounds was reduced by decreasing the pH to 2.0, or by adding epicatechin. We concluded S-methyl methionine and methionine were degraded into volatile sulfur compounds through nucleophilic substitution and Strecker degradation. This study can help establishing protocols for controlling the release of volatile sulfur compounds in heat-sterilized juices.

Genomic analysis suggests Salinispora is a rich source of novel lanthipeptides.

Lanthipeptides are a subgroup of ribosomally encoded and post-translationally modified peptides (RiPPs) which frequently possess potent biological activity. Here we provide the first comprehensive bioinformatic analysis of the lanthipeptide-producing capability of the Salinispora genus, a marine actinomycete. One hundred twenty-two Salinispora arenicola, tropica, and pacifica genomic sequences were analyzed for lanthipeptide gene clusters, and the resulting 182 clusters were divided into seven groups based on sequence similarities. Group boundaries were defined based on LanB and LanM sequences with greater than 80% similarity within groups. Of the seven groups, six are predicted to encode class I lanthipeptides while only one group is predicted to encode class II lanthipeptides. Leader and core peptides were predicted for each cluster along with the number of possible lanthionine bridges. Notably, all of the predicted products of these clusters would represent novel lanthipeptide scaffolds. Of the 122 Salinispora genomes analyzed in this study, 92% contained at least one lanthipeptide gene cluster suggesting that Salinispora is a rich, yet untapped, source of lanthipeptides.

Comparison of volatile trapping techniques for the comprehensive analysis of food flavourings by Gas Chromatography-Mass Spectrometry.

Trapping volatiles is a convenient way to study aroma compounds but it is important to determine which volatile trapping method is most comprehensive in extracting the most relevant aroma components when investigating complex food products. Awareness of their limitations is also crucial. (Un)targeted metabolomic approaches were used to determine the volatile profiles of two commercial flavourings. Four trapping techniques were tested as was the addition of salt to the mixture. Comprehensiveness and repeatability were compared and SBSE proved particularly suitable for extracting components such as polysulfides, pyrazines and terpene alcohols, and provided an overall broader chemical spectrum. SPME proved to be more suitable in extracting sesquiterpenes and DHS in extracting monoterpenes. Adding salt to the sample had only quantitative effects on volatiles as detected by SPME. These results help clarify the advantages and limitations of different trapping techniques and hence deliver a valuable decision tool for food matrix analysis.

Long-term leaching characteristic study of coal processing waste streams.

A study of the mobility of major and potentially hazardous trace elements from coal processing waste materials was conducted using two types of leaching tests. The baseline leaching test simulates stable waste storage under water, whereas the kinetic test models the storage of waste under more variable conditions including intermittent exposure to air and variations in humidity. Coarse and fine refuse materials were obtained from three commercial coal preparation plants that were being used to upgrade US bituminous run-of-mine coal containing low-to-high amounts of pyritic sulfur. X-ray diffraction analyses revealed a large variation in mineralogy between the coarse and fine refuse streams due to the mineral fractionation that occurs in the processing units and plant. The coarse refuse samples contained higher pyrite contents while the fine refuse samples had high clay content and a minor amount of calcite. This variation in mineralogy resulted in relatively large difference in the leaching characteristics of the waste streams. The most acidic pH and highest release of trace elements were observed in the leachate of coarse refuse containing medium-to-high amounts of coal pyrite, while the fine refuse samples released lower amounts of trace elements in their circumneutral leachate. The least amount of trace elements was observed in the leachate of low pyritic refuse streams. The test data suggested that the most effective disposal practice for coal waste material is segregation and isolation of the coal pyrite and co-disposal of the coarse and fine refuse streams.

Sensitive detection of low-concentration sulfide based on the synergistic effect of rGO, np-Au, and recombinant microbial cell.

With the aggravation of sulfide pollution, more and more attention has been paid to the detection of sulfide in the environment. However, the detection of low-concentration sulfide is still a technical bottleneck to be solved urgently. In this study, a synergistic effect strategy that combines the co-catalysis of nanoporous gold (np-Au) and recombinant microbial cell with the excellent electrical conductivity of reduced graphene oxide (rGO) was proposed for the sensitive detection of low-concentration sulfide. A rGO/np-Au composite was fabricated and then used as an immobilization support for the bio-recognition element of recombinant Escherichia coli (E. coli) over-expressed sulfide: quinone oxidoreductase (SQR). A microbial biosensor (E. coliSQR/rGO/np-Au/GCE) was successfully constructed for the sensitive detection of low-concentration sulfide. Due to the synergistic effect of rGO, np-Au, and E. coliSQR cells, the sensitivity of the proposed microbial biosensor towards sulfide reached 400.42 µA mM-1 cm-2 with a wide linear response ranging from 100 nM to 7 mM, as well as a low detection limit of 98.5 nM using amperometric i-t curve method. Furthermore, the microbial biosensor was successfully applied to the detection of sulfide in wastewater with strong anti-interference ability, high reproducibility, and strong stability. These results confirmed that the proposed microbial biosensor was ideal for the detection of low-concentration sulfide in a reliable, specific, and sensitive way.

Effect of microbial nutrients supply on coal bio-desulfurization.

Research on coal desulfurization is very important for economic, social, and environmentally sustainable development. In this study, three batches of shake flask experiments were conducted for coal bio-desulfurization using Acidithiobacillus ferrooxidans to explore the relationship between microbial nutrients (iron-free M9 K medium) supply and coal bio-desulfurization efficiency. The results showed that the removal rates of pyritic sulfur and total sulfur from coal effectively increased following reintroduction of coal into the filtrate from previous batch. The removal rates of pyritic sulfur and total sulfur were 55.6% and 10.0%, 77.1% and 16.1%, and 86.5% and 28.2%, respectively, in the three batch experiments without iron-free M9 K medium addition. In contrast, the removal rates of pyritic sulfur and total sulfur reached 87.5% and 28.2%, 89.1% and 31.6%, and 92.0% and 29.1%, respectively, in the three batch experiments with 6.7% iron-free M9 K medium addition. However, addition of excessive iron-free M9 K medium was detrimental to coal bio-desulfurization because of the synthesis of jarosite (MFe3(SO4)2(OH)6, M = K+, NH4+) and gypsum (CaSO4·2H2O), which further declined the pyritic sulfur bio-oxidation efficiency and total sulfur removal efficiency.

Towards sulfide removal and sulfate reducing bacteria inhibition: Function of biosurfactants produced by indigenous isolated nitrate reducing bacteria.

The effectiveness of nitrate-mediated souring control highly depends on the interactions of sulfate reducing bacteria (SRB) and nitrate reducing bacteria (NRB). Biosurfactants produced by natural NRB are promising bio-agents for enhancing NRB competence towards SRB. However, the function of NRB-produced biosurfactants in NRB-SRB interactions remains unexplored due to the rarely successful isolation of natural biosurfactant-producing NRB. Hereby, biosurfactant-aided inhibitory control of SRB strain Desulfomicrobium escambiense ATCC 51164 by biosurfactant-producing NRB strain Pseudomonas stutzeri CX3, reported in our previous work, was investigated. Under non-sour conditions, insufficient nitrate injection resulted in limited SRB inhibition. Phospholipid fatty acid (PLFA) biomarkers traced the overall bacterial responses. Compositional PLFA patterns revealed biosurfactant addition benefitted both SRB and NRB towards stressful conditions. Under sour conditions, nitrite oxidation of sulfide proved to be the primary mechanism for sulfide removal. The subsequent elevation of redox potential and pH inhibited SRB activities. NRB-produced biosurfactants significantly enhanced SRB inhibition by NRB through more efficient sulfide removal and effective duration of nitrate in the microcosms. Biosurfactants specially produced by the NRB strain are for the first time reported to significantly strengthen SRB inhibition by NRB via reduced nitrate usage and prolonged effective duration of nitrate, which has encouraging potential in nitrate-dependent souring control.

Roseocin, a novel two-component lantibiotic from an actinomycete.

Lantibiotics are lanthionine ring containing natural products that belong to the class of ribosomally synthesized and posttranslationally modified peptides (RiPPs). Recent expansion in the availability of microbial genome data and in silico analysis tools have accelerated the discovery of these promising alternatives to antibiotics. Following the genome-mining approach, a biosynthetic gene cluster for a putative two-component lantibiotic, roseocin, was identified in the genome of an Actinomycete, Streptomyces roseosporus NRRL 11379. Posttranslationally modified lanthipeptides of this cluster were obtained by heterologous expression of the genes in Escherichia coli, and were in vitro reconstituted to their bioactive form by exploiting commercial proteases like endoproteinase GluC, and proteinase K. The two peptides displayed synergistic antimicrobial activity against Gram-positive bacteria including the WHO high-priority pathogens, MRSA and VRE. Structural characterization confirmed the installation of four (methyl)lanthionine rings with an indispensable disulfide bond in the α-peptide, and six (methyl)lanthionine rings in the ß-peptide, by a single promiscuous lanthionine synthetase, RosM. Roseocin is the first two-component lantibiotic from a non-Firmicute, with extensive lanthionine bridging.

Simultaneous sulfide removal, nitrogen removal and electricity generation in a coupled microbial fuel cell system.

A coupled microbial fuel cell (MFC) system, consisting of a nitrifying sulfide removal MFC and a denitrifying sulfide removal MFC, was assembled to simultaneously treat ammonium and sulfide in wastewater. It provided a promising approach to recover electricity from wastewater containing sulfide and ammonium. Considering both substrate removal and electricity generation performance, the desirable feeding S/N molar ratio was deemed as 3 and the optimal temperature was found to be 30 °C. Under this condition, the coupled MFC achieved a sum coulomb production of 554.8 C/d, a total nitrogen removal efficiency of 58.7 ±â€¯1.3% and a sulfur production percent of 27.4 ±â€¯0.4-33.3 ±â€¯0.9%. The introduction of nitrifiers and electroactive oxic microbes from the oxic-cathode chamber into the anoxic-cathode chamber favored nitrogen removal.

Anaerobic digestion of wastewater rich in sulfate and sulfide: effects of metallic waste addition and micro-aeration on process performance and methane production.

This work explores the effect of two metallic wastes (mining wastes, MW; fly ashes, FA) and micro-aeration (MA) on the anaerobic digestion of wastewater which is rich in sulfate and sulfide. Two initial COD concentrations (5,000 and 10,000 mg/L) were studied under both conditions in batch systems at 35 °C, with a fixed COD/SO42- ratio = 10, with 100 mg/L of S2-. It was observed that the use of MW and FA in the assays with an initial COD concentration of 10,000 mg/L resulted in a simultaneous increase in COD removal, sulfate removal, sulfide removal and methane generation, while MA only improved the COD and sulfide removals in comparison with the control system. On the contrary, the use of MW, FA or MA in systems with initial COD concentrations equal to or lower than 5,000 mg/L did not show any improvement with respect to the control system in terms of COD removal, sulfate removal or methane generation, with only sulfide removal being positively affected by MW and FA.

Simultaneous nitrate and sulfide removal using a bio-electrochemical system.

This study addresses the applicability of simultaneous nitrate and sulfide removal using two-chamber bio-electrochemical systems (BES). The anode and cathode chambers of a BES were fed with the effluent of a sulfate reducing reactor and a nitrate-rich groundwater as an electron donor and acceptor sources, respectively. BES has been found to be effective for simultaneous removal of sulfide and nitrate coming from different sources and without mixing them. As a result, 10 gS/m3/d of sulfide oxidation and 7.26 gN/m3/d of nitrate reduction rates were achieved. The number of electrons used for denitrification was more than that of delivered from the anode, especially when the anode chamber was fed with the SRR effluent and operated at pH 7-7.5. It was supposed that H2S was used for denitrification in the cathode by passing through the membrane. Another reason for this might be the electrons released from the corroding steel mesh current collector.

An integrated method for controlling the offensive odor and suspended matter originating from algae-induced black blooms.

Potentially toxic algae-induced black blooms can trigger crises in urban water supplies and have fatal effects on aquatic ecosystems. Urgent disposal methods to mitigate the taste and odor are imperative for ensuring the safety of the drinking water supply. In this study, we tested three oxidants and two flocculants to improve water quality after the occurrence of a black bloom. The results indicated that a two-step integrated treatment process is efficient as an urgent disposal measure. The first step is removal of volatile organic sulfide compounds (VOSCs) through the addition of H2O2. A total of 50 mg/L of H2O2 can largely decrease the concentrations of dimethyl trisulfide and related alkyl sulfide compounds in the water column. The second step is the flocculation and sedimentation of black-bloom-induced black matter via a chitosan-modified clay. The addition of 1 g/L of an attapulgite clay plus 10 mg/L of chitosan can effectively deposit suspended matter on the bottom of the water column and have a positive effect on the removal of nutrients.

Anammox granule as new inoculum for start-up of anaerobic sulfide oxidation (ASO) process and its reverse start-up.

The feasibility of implementing anaerobic ammonium oxidation (anammox) granules to start up high-loading anaerobic sulfide oxidation (ASO) in an upflow anaerobic sludge bed (UASB) reactor was investigated. An innovation method of the reverse start-up of anammox was also validated. Firstly, the reactor was operated to treat sulfide-rich wastewaters into which nitrite was introduced as an electron acceptor. An high-rate performance with sulfide and nitrate removal rates of 105.5 ±â€¯0.11 kg S m-3 d-1 and 28.45 ±â€¯3.40 kg N m-3 d-1, respectively, was accomplished. Sulfurovum were enriched with the increase of the substrate load and then conquered Candidatus Kuenenia to be the predominant bacteria. Excitation-emission matrix (EEM) spectroscopy showed that the intensities of fluorescence decreased and protein-like substrates were the main components associated with the process of start-up. FT-IR analysis found that the main functional groups indicator were O-H groups. Secondly, the reverse start-up of anammox (achieving 90% TN removal) was achieved immediately when the substrate changed. 16S rRNA analysis indicated the successfully enrichment of anammox bacteria (Candidatus Kuenenia). These results suggest that anammox granules can act as inoculum of high-loading ASO process and the reverse start-up provides a new perspective for the fast initiation of anammox process.

Allyl methyl sulfide, a garlic active component mitigates hyperglycemia by restoration of circulatory antioxidant status and attenuating glycoprotein components in streptozotocin-induced experimental rats.

Diabetes is a major noncommunicable life-threatening chronic and pervasive condition that is consuming the world health in a petrifying rate. The circulatory system is one of the major sources of hyperglycemia-induced ROS generation. Historically, garlic has been revered as part of a healthful diet. Organosulfur compounds have been attributed to the medicinal properties and health benefits of garlic. The present study focuses on the ameliorative role of allyl methyl sulfide (AMS) in combating diabetic complications in diabetic rats. Male Wistar rats were randomly divided into four groups. Experimental diabetes was induced by a single intraperitoneal injection (i.p), of streptozotocin (STZ) (40 mg/kg b.w). STZ treated diabetic rats showed significant augment in plasma glucose level, lipidperoxidative (LPO) markers, glycoprotein components (hexose, hexosamine, sialic acid, and fucose), and significant decline in plasma insulin level, nonenzymatic antioxidants and activities of antioxidant enzymes in the circulatory system and tissues. Further, periodic acid-Schiff (PAS) staining of hepatic and renal tissues revealed positive stain accumulation and Western blot investigation of glucose transporter 2 (GLUT 2) in pancreas of STZ-induced hyperglycemic rats. Dietary intervention with AMS (100 mg/kg b.w) for 30 days demonstrated significant protective effects on all the biochemical parameters studied. Besides, biochemical findings were corroborated by histological exertion and Western blot study. The findings of current investigations recommended that AMS can ameliorate the consequences of diabetes due to their antioxidant efficacy and can be used as a potential therapeutic approach. Further studies are warranted to explore the clinical application of AMS.

Haloalkaliphilic microorganisms assist sulfide removal in a microbial electrolysis cell.

Several industrial processes produce toxic sulfide containing streams that are often scrubbed using caustic solutions. An alternative, cost effective sulfide treatment method is bioelectrochemical sulfide removal. For the first time, a haloalkaliphilic sulfide-oxidizing microbial consortium was introduced to the anodic chamber of a microbial electrolysis cell operated at alkaline pH and with 1.0 M sodium ions. Under anode potential control, the highest sulfide removal rate was 2.16 mM/day and chemical analysis supported that the electrical current generation was from the sulfide oxidation. Biotic operation produced a maximum current density of 3625 mA/m2 compared to 210 mA/m2 while under abiotic operation. Furthermore, biotic electrical production was maintained for a longer period than for abiotic operation, potentially due to the passivation of the electrode by elemental sulfur during abiotic operation. The use of microorganisms reduced the energy input in this study compared to published electrochemical sulfide removal technologies. Sulfide-oxidizing populations dominated both the planktonic and electrode-attached communities with 16S rRNA gene sequences aligning within the genera Thioalkalivibrio, Thioalkalimicrobium, and Desulfurivibrio. The dominance of the Desulfurivibrio-like population on the anode surface offered evidence for the first haloalkaliphilic bacterium able to couple electrons from sulfide oxidation to extracellular electron transfer to the anode.

Comparison of sulphide and nitrate removal from synthetic wastewater by pure and mixed cultures of nitrate-reducing, sulphide-oxidizing bacteria.

In this study, the activities of hydrogen sulphide (H2S) oxidation and nitrate (N-NO3-) reduction by three pure and mixed strains of nitrate-reducing, sulphide oxidizing bacteria (NR-SOB) were determined. Batch experiments were performed at 35 °C and pH 7.0-8.0 with initial H2S concentrations of 650-900 ppmv and N-NO3- concentrations of ∼120 mg/L. The strains MAL 1HM19, TPN 1HM1 and TPN 3HM1 were capable of removing 100% gas-phase H2S. The co-cultures showed better performance for H2S and N-NO3- removal. The mixed NR-SOB strains showed a higher H2S oxidation rate (143 ±â€¯18 ppmv/h), while the highest N-NO3- removal rate (5.5 ±â€¯0 and 5.1 ±â€¯0.6 N-NO3- mg/L·h) was obtained by a mixture of two NR-SOB strains. The 16S rDNA sequence analysis revealed that all strains belonged to the sub-class Alphaproteobacteria and are closely related to Paracoccus sp. (>99%).

Activity of Thioallyl Compounds From Garlic Against Giardia duodenalis Trophozoites and in Experimental Giardiasis.

Fresh aqueous extracts (AGEs) and several thioallyl compounds (TACs) from garlic have an important antimicrobial activity that likely involves their interaction with exposed thiol groups at single aminoacids or target proteins. Since these groups are present in Giardia duodenalis trophozoites, in this work we evaluated the anti-giardial activity of AGE and several garlic's TACs. In vitro susceptibility assays showed that AGE affected trophozoite viability initially by a mechanism impairing cell integrity and oxidoreductase activities while diesterase activities were abrogated at higher AGE concentrations. The giardicidal activities of seven TACs were related to the molecular descriptor HOMO (Highest Occupied Molecular Orbital) energy and with their capacity to modify the -SH groups exposed in giardial proteins. Interestingly, the activity of several cysteine proteases in trophozoite lysates was inhibited by representative TACs as well as the cytopathic effect of the virulence factor giardipain-1. Of these, allicin showed the highest anti-giardial activity, the lower HOMO value, the highest thiol-modifying activity and the greatest inhibition of cysteine proteases. Allicin had a cytolytic mechanism in trophozoites with subsequent impairment of diesterase and oxidoreductase activities in a similar way to AGE. In addition, by electron microscopy a marked destruction of plasma membrane and endomembranes was observed in allicin-treated trophozoites while cytoskeletal elements were not affected. In further flow cytometry analyses pro-apoptotic effects of allicin concomitant to partial cell cycle arrest at G2 phase with the absence of oxidative stress were observed. In experimental infections of gerbils, the intragastric administration of AGE or allicin decreased parasite numbers and eliminated trophozoites in experimentally infected animals, respectively. These data suggest a potential use of TACs from garlic against G. duodenalis and in the treatment of giardiasis along with their additional benefits in the host's health.

Mitigating adverse impacts of varying sulfide/nitrate ratios on denitrifying sulfide removal process performance.

Complete removal of nitrogen, sulfur and carbon in wastewaters by denitrifying sulfide removal (DSR) process can be achieved at stoichiometry sulfide to nitrate ratio (S/N) of 1:1 in expanded granular sludge bed reactor. Wastewaters with varying S/N ratios can adversely impact the DSR performances with deterioration of synergetic cooperation between autotrophic and heterotrophic denitrifiers. DO (dissolved oxygen) serves effectively as supplementary electron receiver for sulfide oxidation, leaving more nitrate for heterotrophic denitrifiers to utilize acetate. The optimal oxygen to sulfide molar ratio (DO/S) is 0.5:1 for complete removal of sulfide, nitrate and acetate at different S/N ratios. The heterotrophic denitrification rate was decreased to 0.03 ±â€¯0.002, 0.24 ±â€¯0.011 and 0.35 ±â€¯0.027 NO3--N·h-1·gVSS-1 at S/N ratio of 5:2, 5:5 and 5:8, respectively, when DO/S of 3:1 was performed. This optimal condition was proposed as an easy-to-implement control criterion for subsiding the adverse impact by varying S/N ratios in handling real wastewaters.