Naturally Occurring Flavonoids Against Human Norovirus Surrogates

Naturally occurring plant-derived flavonoids are reported to have antibacterial, antiviral, and pharmacological activities. The objectives of this study were to determine the antiviral effects of four flavonoids (myricetin, l-epicatechin, tangeretin, and naringenin) on the infectivity of food borne norovirus surrogates after 2 h at 37 °C. The lab-culturable surrogates, feline calicivirus (FCV-F9) at titers of ~7 log₁₀ PFU/ml (high titer) or ~5 log₁₀ PFU/ml (low titer) and murine norovirus (MNV-1) at ~5 log₁₀ PFU/ml, were mixed with equal volumes of myricetin, l-epicatechin, tangeretin, or naringenin at concentrations of 0.5 or 1 mM, and incubated for 2 h at 37 °C. Treatments of viruses were neutralized in cell culture medium containing 10 % heat-inactivated fetal bovine serum, serially diluted, and plaque assayed. Each treatment was replicated thrice and assayed in duplicate. FCV-F9 (low titer) was not found to be reduced by tangeretin or naringenin, but was reduced to undetectable levels by myricetin at both concentrations. Low titer FCV-F9 was also decreased by 1.40 log₁₀ PFU/ml with l-epicatechin at 0.5 mM. FCV-F9 at high titers was decreased by 3.17 and 0.72 log₁₀ PFU/ml with myricetin and l-epicatechin at 0.5 mM, and 1.73 log₁₀ PFU/ml with myricetin at 0.25 mM, respectively. However, MNV-1 showed no significant inactivation by the four tested treatments. The antiviral effects of the tested flavonoids are dependent on the virus type, titer, and dose. Further research will focus on understanding the antiviral mechanism of myricetin and l-epicatechin.     

Curcumin-Mediated Photodynamic Inactivation of Norovirus Surrogates

Photodynamic inactivation (PDI) is extensively used to inactivate different type of pathogens through the use of photosensitizers (PS). Curcumin has been identified as an excellent natural photosensitizer with some potential applications in the food industry. The aim of this study was to assess the antiviral activity of photoactivated curcumin on norovirus surrogates, feline calicivirus (FCV), and murine norovirus (MNV). Initially, different concentrations of curcumin (13.5–1358 µM) were individually mixed with each virus at titers of ca. 6–7 log TCID₅₀/ml and photoactivated by LED blue light with light dose of 3?J/cm². Results showed that photoactivated curcumin at 50 µg/mL reduced FCV titers by almost 5 log after incubation at 37 °C for 30 min. Lower antiviral activity (0.73 log TCID₅₀/mL reduction) was reported for MNV. At room temperature, curcumin at 5 µg/mL reduced FCV titers by 1.75 log TCID₅₀/mL. These results represent a step forward in improving food safety using photoactivated curcumin as an alternative natural additive to reduce viral contamination.     

Aqueous Extracts of <Emphasis Type="Italic">Hibiscus sabdariffa</Emphasis> Calyces to Control Aichi Virus

Aqueous Hibiscus sabdariffa extracts possess antimicrobial properties with limited information available on their antiviral effects. Aichi virus (AiV) is an emerging foodborne pathogen that causes gastroenteritis. Vaccines are currently unavailable to prevent their disease transmission. The objective of this study was to determine the antiviral effects of aqueous H. sabdariffa extracts against AiV. AiV at ~5 log PFU/ml was incubated with undiluted (200 mg/ml), 1:1 (100 mg/ml) or 1:5 (40 mg/ml) diluted aqueous hibiscus extract (pH 3.6), phosphate-buffered saline (pH 7.2 as control), or malic acid (pH 3.0, acid control) at 37 °C over 24 h. Treatments were stopped by serially diluting in cell-culture media containing fetal bovine serum and titers were determined using plaque assays on confluent Vero cells. Each treatment was replicated thrice and assayed in duplicate. AiV did not show any significant reduction with 1:1 (100 mg/ml) or 1:5 (40 mg/ml) diluted aqueous hibiscus extracts or malic acid after 0.5, 1, or 2 h at 37 °C. However, AiV titers were reduced to non-detectable levels after 24 h with all the three tested concentrations, while malic acid showed only 0.93 log PFU/ml reduction after 24 h. AiV was reduced by 0.5 and 0.9 log PFU/ml with undiluted extracts (200 mg/ml) after 2 and 6 h, respectively. AiV treated with 1:1 (100 mg/ml) and 1:5 (40 mg/ml) diluted extracts showed a minimal ~0.3 log PFU/ml reduction after 6 h. These extracts show promise to reduce AiV titers mainly through alteration of virus structure, though higher concentrations may have improved effects.     

Efficacy of Cinnamaldehyde Against Enteric Viruses and Its Activity After Incorporation Into Biodegradable Multilayer Systems of Interest in Food Packaging

Cinnamaldehyde (CNMA), an organic compound that gives cinnamon its flavor and odor, was investigated for its virucidal activity on norovirus surrogates, murine norovirus (MNV) and feline calicivirus (FCV), and hepatitis A virus (HAV). Initially, different concentrations of CNMA (0.1, 0.5 and 1 %) were individually mixed with each virus at titers of ca. 6–7 log₁₀ TCID₅₀/ml and incubated 2 h at 4 and 37 °C. CNMA was effective in reducing the titers of norovirus surrogates in a dose-dependent manner after 2 h at 37 °C, while HAV titers were reduced by 1 log₁₀ after treatment with 1 % of CNMA. When incubation time was extended, HAV titers were reduced by 3.4 and 2.7 log₁₀ after overnight incubation at 37 °C with 1 and 0.5 % of CNMA, respectively. Moreover, this paper analyzed, for the first time, the antiviral activity of adding an active electrospun interlayer based on zein and CNMA to a polyhydroxybutyrate packaging material (PHB) in a multilayer form. Biodegradable multilayer systems prepared with 2.60 mg/cm² (~9.7 %) of CNMA completely inactivated FCV according to ISO 22196:2011, while MNV titers were reduced by 2.75 log₁₀. When the developed multilayer films were evaluated after one month of preparation or at 25 °C, the antiviral activity was reduced as compared to freshly prepared multilayer films evaluated at 37 °C. The results show the excellent potential of this system for food contact applications as well as for active packaging technologies in order to maintain or extend food quality and safety.     

Reduction of Enteric Viruses by Blueberry Juice and Blueberry Proanthocyanidins

Blueberry and blueberry extracts are known for their health benefits and antimicrobial properties. Natural therapeutic or preventive options to decrease the incidences of foodborne viral illnesses are becoming popular and being researched. This study aimed to determine the antiviral effects of blueberry juice (BJ) and blueberry proanthocyanidins (BB-PAC, B-type PAC structurally different from A-type PAC found in cranberries) against the infectivity of hepatitis A virus (HAV) and human norovirus surrogates (feline calicivirus (FCV-F9) and murine norovirus (MNV-1)) at 37 °C over 24 h using standard plaque assays. Viruses at ~5 log PFU/ml were mixed with equal volumes of BJ (pH 2.8), neutralized BJ (pH 7.0), BB-PAC (1, 2, 4, and 10 mg/ml), malic acid (pH 3.0), or phosphate-buffered saline (pH 7.2) and incubated over 24 h at 37 °C. Each experiment was carried out in duplicate and replicated thrice. FCV-F9 titers were found to be reduced to undetectable levels with 1 and 2 mg/ml BB-PAC after 5 min, with 0.5 mg/ml BB-PAC after 1-h, and with BJ after 3-h. MNV-1 titers were reduced to undetectable levels after 3 h with 1, 2, and 5 mg/ml BB-PAC and after 6 h with BJ. HAV titers were reduced to undetectable levels after 30 min with 2 and 5 mg/ml BB-PAC, after 3 h with 1 mg/ml BB-PAC, and by ~2 log PFU/ml with BJ after 24-h. BB-PAC shows preventive potential against infection by the tested enteric viruses in a dose- and time-dependent manner, although further in vitro studies in model food systems and in vivo studies using animal models are warranted.     

Impact of Sodium Chloride, Sucrose and Milk on Heat Stability of the Murine Norovirus and the MS2 Phage

Until now, little is known about the influence of food additives on heat inactivation of noroviruses. Only a few studies have shown a protective or inhibiting effect on virus infectivity caused by the food matrix. Therefore, the aim of this study was to examine the influence of sodium chloride, sucrose and milk on heat stability of the surrogates murine norovirus (MNV) and MS2 phage at 60 °C for 1–5 min in PBS for MNV and for 5–120 min in suspension medium buffer for MS2 phage. Different concentrations of sodium chloride (5, 10 %) and sucrose (5, 50 %) were added to the respective buffers. In addition, commercially available milk with different fat concentrations (0.3, 1.5, 3.5 %) was investigated in this study. In general, a linear titre reduction for MNV and MS2 phage could be observed, except for the heat treatment of MNV in PBS with 50 % sucrose. A protective effect of PBS with 50 % sucrose and of the matrix milk on MNV could be concluded. All other tested conditions did not show any influence on virus inactivation. However, MS2 phage did show a higher heat resistance throughout the experiments compared to MNV. In future investigations, it should be tested, whether the achieved data may be considered in risk assessments of heat-treated food products with high concentrations of sugar. Furthermore, it should be clarified, whether these results can also be referred to complex food matrices.     

Evaluation of a Porcine Gastric Mucin and RNase A Assay for the Discrimination of Infectious and Non-infectious GI.1 and GII.4 Norovirus Following Thermal,Ethanol, or Levulinic Acid Plus Sodium Dodecyl Sulfate Treatments

Human noroviruses (NoVs) are a major source of foodborne illnesses worldwide. Since human NoVs cannot be cultured in vitro, methods that discriminate infectious from non-infectious NoVs are needed. The purpose of this study was to evaluate binding of NoV genotypes GI.1 and GII.4 to histo-blood group antigens expressed in porcine gastric mucin (PGM) as a surrogate for detecting infectious virus following thermal (99 °C/5 min), 70 % ethanol or 0.5 % levulinic acid (LV) plus 0.01 or 0.1 % sodium dodecyl sulfate (SDS) sanitizer treatments and to determine the limit of detection of GI.1 and GII.4 binding to PGM. Treated and control virus samples were applied to 96-well plates coated with 1 µg/ml PGM followed by RNase A (5 ng/µl) treatment for degradation of exposed RNA. Average log genome copies per ml (gc/ml) reductions and relative differences (RD) in quantification cycle (Cq) values after thermal treatment were 1.77/5.62 and 1.71/7.25 (RNase A) and 1.73/5.50 and 1.56/6.58 (no RNase A) for GI.1 and GII.4, respectively. Treatment of NoVs with 70 % EtOH resulted in 0.05/0.16 (GI.1) and 3.54/10.19 (GII.4) log reductions in gc/ml and average RD in Cq value, respectively. LV (0.5 %) combined with 0.1 % SDS provided a greater decrease of GI.1 and GII.4 NoVs with 8.97 and 8.13 average RD in Cq values obtained, respectively than 0.5 % LV/0.01 % SDS. Virus recovery after PGM binding was variable with GII.4 > GI.1. PGM binding is a promising surrogate for identifying infectious and non-infectious NoVs after capsid destruction, however, results vary depending on virus strain and inactivation method.     

Inhibition of Murine Norovirus and Feline Calicivirus by Edible Herbal Extracts

Human noroviruses (HuNoVs) cause foodborne and waterborne viral gastroenteritis worldwide. Because HuNoV culture systems have not been developed thus far, no available medicines or vaccines preventing infection with HuNoVs exist. Some herbal extracts were considered as phytomedicines because of their bioactive components. In this study, the inhibitory effects of 29 edible herbal extracts against the norovirus surrogates murine norovirus (MNV) and feline calicivirus (FCV) were examined. FCV was significantly inhibited to 86.89 ± 2.01 and 48.71 ± 7.38% by 100 μg/mL of Camellia sinensis and Ficus carica, respectively. Similarly, ribavirin at a concentration of 100 μM significantly reduced the titer of FCV by 77.69 ± 10.40%. Pleuropterus multiflorus (20 μg/mL) showed antiviral activity of 53.33 ± 5.77, and 50.00 ± 16.67% inhibition was observed after treatment with 20 μg/mL of Alnus japonica. MNV was inhibited with ribavirin by 59.22 ± 16.28% at a concentration of 100 μM. Interestingly, MNV was significantly inhibited with 150 µg/mL Inonotus obliquus and 50 μg/mL Crataegus pinnatifida by 91.67 ± 5.05 and 57.66 ± 3.36%, respectively. Treatment with 20 µg/mL Coriandrum sativum slightly reduced MNV by 45.24 ± 4.12%. The seven herbal extracts of C. sinensis, F. carica, P. multiflorus, A. japonica, I. obliquus, C. pinnatifida, and C. sativum may have the potential to control noroviruses without cytotoxicity.     

Spatial and temporal distribution of Mo in the overlying water of a reservoir downstream from mining area

This study aimed to evaluate the spatial and temporal variations of molybdenum (Mo) in the downstream water body of a Mo mine during three hydrologic periods (wet, dry and medium seasons). The physical properties in Luhun Reservoir reflected seasonal variations in different hydrological periods. The redox potential (ORP) and dissolved oxygen (DO) increased in the dry season. The concomitant decrease in temperature (T), conductivity (COND) and total dissolved solids (TDS) were lowest in the wet season. The pH value did not change significantly during the three hydrologic periods. The distribution of Mo in the dry season was high in upstream and low in downstream areas, which was significantly different from that of the wet and medium seasons. The total Mo concentration in wet (150.1 µg/L) and medium season (148.2 µg/L) was higher than that in the dry season, but the TDS (288.3 mg/L) and the percentage dissolved Mo (81.3%) in overlying water was lowest in the wet season. There was no significant relationship between the dissolved Mo and the total Mo with TDS. In the dry season, the mean total Mo concentration was 116.3 µg/L, which was higher than the standard limit value (70 µg/L) for drinking water (US EPA-United States Environmental Protection Agency recommended value 40 µg/L). Non-point source pollution is the main characteristic of mining area pollution, which was closely related to rainfall. Thus, the Luhun Reservoir contains substantial Mo pollution, which was a significant concern given that it is used as a source of drinking and irrigation water.     

The concentration and probabilistic risk assessment of potentially toxic elements in fillets of silver pomfret (Pampus argenteus): A global systematic review and meta-analysis

The contamination of fish type products such as silver pomfret fish fillets by potentially toxic elements (PTEs) has raised global health concerns. Related studies regarding the concentration of PTEs in fillets of silver pomfret fish were retrieved among some international databases such as Scopus, PubMed and Embase between 1 January 1983 and 10 March 2020. The pooled (mean) concentration of PTEs in fillets of silver pomfret fish was meta-analyzed with the aid of a random-effect model (REM). Also, the non-carcinogenic risk was estimated via calculating the 95th percentile of the total target hazard quotient (TTHQ). The meta-analysis of 21 articles (containing 25 studies or data reports) indicated that the ranking of PTEs in fillets of silver pomfret fish was Fe (11,414.81 µg/kg wet weight, ww) > Zn (6055.72 µg/kg ww) > Cr (1825.79 µg/kg ww) > Pb (1486.44 µg/kg ww) > Se (1053.47 µg/kg ww) > Cd (992.50 µg/kg ww) > Ni (745.23 µg/kg ww) > Cu (669.71 µg/kg ww) > total As (408.24 µg/kg ww) > Co (87.03 µg/kg ww) > methyl Hg (46.58 µg/kg ww). The rank order of health risk assessment by country based on the TTHQ for adult consumers was Malaysia (2.500) > Bangladesh (0.886) > Iran (0.144) > China (0.045) > Pakistan (0.020) > India (0.015), while the corresponding values for child consumers was Malaysia (11.790) > Bangladesh (4.146) > Iran (0.675) > China (0.206) > Pakistan (0.096) > India (0.077). The adult consumers in Malaysia and children in Malaysia and Bangladesh were at considerable non-carcinogenic risk. Therefore, following the recommended control plans in order to reduce the health risk associated with the ingestion of PTEs via consumption of silver pomfret fish fillets is crucial.     

Antiviral Potential of Selected Starter Cultures,Bacteriocins and d,l-Lactic Acid

The antiviral potential of selected bacteria species [lactic acid bacteria (LAB) and micrococcaceae] was examined. By this, the effect of their cell-free supernatants as well as of certain species-related metabolites (sakacin A, nisin, and lactic acid) was investigated on different viruses after exposure at 24 °C for 3 days. Viruses were incubated with supernatants and metabolites in a dilution ratio of 1:10. Data for antiviral effects towards murine norovirus S99 (MNV), influenza A virus A/WSN/33 (H1N1), Newcastle disease virus Montana (NDV) and feline herpesvirus KS 285 (FHV) were generated in vitro simulating pH and temperature conditions according to raw sausage fermentations. Investigations showed no antiviral effect of sakacin A and nisin on MNV, H1N1, FHV and NDV. Furthermore, the antiviral potential of d,l-lactic acid was determined for MNV and H1N1. At raw sausage-related pH values (5.0–6.2) it could be shown that the virus titre for MNV and H1N1 was reduced by a maximum of 3.25 log and 2.5 log units, respectively. In addition, 29 culture supernatants of different bacteria species, mainly LAB and staphylococci, were tested for their antiviral activity against MNV. Only the cell-free supernatant of a Lb. curvatus strain showed a higher virus titre reduction of MNV by 1.25 log units compared to the control. Further studies on the characterisation of this cell-free supernatant were carried out, however, the antiviral substance could not be identified so far.     

Preliminary Source Tracking of Male-Specific (F<Superscript>+</Superscript>) RNA Coliphage on Lettuce as a Surrogate of Enteric Viruses Using Reverse Transcription-PCR

The aim of this research was to preliminary track fecal source male-specific F⁺RNA coliphages including human and animals in lettuce. At first, two published virus extraction procedures of ultracentrifugation and PEG precipitation were compared using DAL assay for determining the recovery efficiency in lettuce spiked artificially with three concentrations (10², 10⁴, 10⁶ pfu/100 ml) of MS2 coliphage. The results showed that PEG precipitation had the highest recovery in which the recovery efficiency at the spiked level of 10⁶ pfu/100 ml was 16.63 %. Aqueous phase obtained from the final step of PEG method was applied for enumeration of coliphage and viral RNA extraction in naturally contaminated lettuce samples (N = 30) collected from two sources (market and farm). The samples were then analyzed based on (I, II, III, and IV primer sets) using RT-PCR method. Coliphages were detected in 9 (60 %) and 12 (80 %) out of 15 market and farm samples, respectively, using DAL assay, whereas male-specific F⁺RNA coliphages were detected using the RT-PCR method in 9 (60 %) and 13 (86.6 %) out of 15 samples of market and farm, respectively. Based on the results, only genotype I of male-specific F⁺RNA coliphages was detected in lettuce samples and no sample tested was positive for other genotypes (II, III, and IV).     

Antiviral Activity of Ctn[15-34], A Cathelicidin-Derived Eicosapeptide,Against Infectious Myonecrosis Virus in <Emphasis Type="Italic">Litopenaeus vannamei</Emphasis> Primary Hemocyte Cultures

The shrimp farming has been converted into a mature aquaculture industry dealing with over millions of metric tonnes of processed commodities. Nevertheless, the global shrimp productions are constantly threatened by disease outbreaks, mainly triggered by rapidly disseminating viruses. Infectious myonecrosis virus (IMNV) is one of these epizootic agents affecting shrimp production in Brazil, of which no treatment exists. Herein, the antiviral activity against IMNV of an eicosapeptide, named Ctn[15-34], derived from a member of the cathelicidin family of antimicrobial peptides, was demonstrated. Cultures of hemocytes from Litopenaeus vannamei were established that support IMNV replication and infectivity titration. The cytotoxic effect of IMNV in culture and the in vitro anti-IMNV activity of Ctn[15-34] were assessed using a high-sensitive fluorescent-based method in combination with quantitative PCR. The Ctn[15-34] (<12.5 µM) neutralized the toxic effects of IMNV at loads sufficient to kill 50% of shrimp hemocytes. This study reported for the first time the replication of IMNV in vitro and the employment of a straightforward methodology to assess cell viability and viral/antiviral activities. In addition, it provided the basis for the development of the anti-infective multi-effector Ctn[15-34] eicosapeptide and analogs as components of antiviral formulations against shrimp viral diseases.     

Optimized pre-treatment of high strength food waste digestate by high content aluminum-nanocluster based magnetic coagulation

Coagulation-based pre-treatment efficiency of high strength digestate of food waste (HSDFW) anaerobic digestion is negated by organic ligand-catalyzed decomposition of coagulants. In this study, an efficient HSDFW pre-treatment method, magnetic seeds (MS) coagulation, was employed by using highly stable Keggin Al₃₀ nanocluster (PAC₃₀), MS and polyacrylamide (PAM), and its operation was optimized by evaluating the performance of removing turbidity, total suspended solids (TSS), chemical oxygen demand (COD), and total phosphorous (TP) phosphate. Results showed that at the optimum dosage of 4.82 g/L, PAC₃₀ demonstrated excellent removals as high as 98.93% ± 0.1% of turbidity, 98.04% ± 0.1% of TSS, 58.28% ± 0.3% of total COD, 99.98% ± 0.01% of TP and 99.50% ± 0.01% of dissolved phosphate, respectively. Apparent molecular weight (AMW) and three-dimensional excitation-emission matrix (3D-EEM) fluorescence spectroscopy analyses demonstrated more efficient removal of dissolved organic matter (DOM), particularly non-biodegradable and hydrophobic components by PAC₃₀ than commercial coagulant. The sedimentation was much improved from 40 min by coagulation/flocculation to about 5 min settling by MS coagulation. The PAC₃₀ based magnetic coagulation (MC) presents theoretical guidance on a cost-effective and much less footprint pre-treatment alternative for high strength wastewater.     

Effect of pH on Anti-Rotavirus Activity by Comestible Juices and Proanthocyanidins in a Cell-Free Assay System

Cranberry (Vaccinium macrocarpon) and grape (Vitis labrusca) juices, and these species?? secondary plant metabolites [i.e., proanthocyanidins (PACs)] possess antiviral activity. An understanding of the mechanism(s) responsible for these juices and their polyphenolic constituents?? direct effect on enteric virus integrity, however, remains poorly defined. Using the rotavirus (RTV) as a model enteric virus system, the direct effect of manufacturer-supplied and commercially purchased juices [Ocean Spray Pure Cranberry 100?% Unsweetened Juice (CJ), Welch??s 100?% Grape Juice (GJ), 100?% Concord (PG) and 100?% Niagara juices (NG)] and these species?? cranberry (C-PACs) and grape PACs (G-PACs) was investigated. Loss of viral capsid integrity in cell-free suspension by juices and their PACs, and as a factor of pH, was identified by an antigen (RTV) capture enzyme-linked immunosorbent assay. At native and an artificially increased suspension at or near pH 7, loss of viral infectivity occurred after 5?min, in the order CJ?>?NG?=?GJ?>?PG, and PG?>?GJ?=?NG?=?CJ, respectively. Antiviral activity of CJ was inversely related to pH. Grape, but not cranberry PACs, displayed a comparatively greater anti-RTV activity at a suspension pH of 6.7. Anti-RTV activity of C-PACs was regained upon reduction of RTV-cranberry PAC suspensions to pH 4. An alteration or modification of Type A PAC (of V. macrocarpon) structural integrity at or near physiologic pH is suggested to have impacted on this molecule??s antivirus activity. Type B PACs (of V. labrusca) were refractive to alternations of pH. Significantly, findings from pure system RTV?CPAC testing paralleled and in turn, supported those RTV-juice antiviral studies. Electron microscopy showed an enshroudment by PACs of RTV particles, suggesting a blockage of viral antigenic binding determinants. The implications of our work are significant, especially in the interpretation of PAC (and PAC-containing food)?CRTV interactions in the differing [pH] conditions of the gastrointestinal tract.     

Peat emission control by groundwater management and soil amendments: evidence from laboratory experiments

Peat respiration that releases carbon dioxide (CO₂) to the atmosphere contributes to regional and global change. Aeration associated with soil water content levels controls emission rates, but soil amendments might mitigate respiration. The objectives of this study were to examine the effects of various water content levels and laterite application on microbial (heterotrophic) respiration in peat soil. Bulk samples of surface (0–20 cm depth) and subsurface (30–50 cm depth) layers were collected from an oil palm plantation in Riau Province, Indonesia. Peat water content was adjusted to 20, 40, 60, 80, and 100 % water filled pore space (WFPS). Laterite soil (clay containing high Al and Fe oxides) was applied to 3, 6, and 12 mg g^?1 dry weight (1.2, 2.4, and 4.8 Mg ha^?1) peat samples at 60 % and 100 % WFPS. Results showed peat respiration was notably affected by water content, but less affected by laterite application. Peat respiration increased sharply from wet (≥80 % WFPS) to moist soil (60 to 40 % WFPS), and decreased when soil dried (≤40 % WFPS). Laterite as a peat ameliorant accelerated rather than reduced peat respiration, and is therefore not a viable choice for CO₂ emissions reduction.     

The Effect of Heat on the Physicochemical Properties of Bacteriophage MS2

The differences in physicochemical characteristics between infectious and non-infectious viral particles are poorly known. Even for heat, which is known as one of the most efficient treatments to inactivate enteric viruses, the global inactivation mechanisms have not been described yet. Such knowledge would help distinguish between both types of particles and therefore clarify the interpretation of the presence of viral genomes in food after heat treatment. In this study, we examined in particular the differences in electrostatic charge and hydrophobicity between the two particle types. MS2 phage, a common surrogate for enteric viruses, was used as a model virus. The heat-induced inactivation process of the infectious phages caused hydrophobic domains to be transiently exposed and their charge to become less negative. The particles also became progressively permeable to small molecules such as SYPRO Orange dye. The presence of non-infectious phage particles in which the genome was not accessible to RNases has been clearly demonstrated. These observations were done for MS2 phages exposed to a temperature of 60 °C. When exposed to a temperature higher than their critical temperature (72 °C), the particles were disrupted and the genome became available for RNases. At lower temperatures, 60 °C in this study, the transient expression of hydrophobic domains of remaining infectious phages appeared as an interesting parameter for improving their specific detection.     

Relationships between chemical elements of PM2.5 and O3 in Shanghai atmosphere based on the 1-year monitoring observation

Mass level of fine particles (PM_2.5) in main cities in China has decreased significantly in recent years due to implementation of Chinese Clean Air Action Plan since 2013, however, O₃ pollution is getting worse than before, especially in megacities such as in Shanghai. In this work, O₃ and PM_2.5 were continuously monitored from May 27, 2018 to March 31, 2019. Our data showed that the annual average concentration of PM_2.5 and O₃ (O₃-8 hr, maximum 8-hour moving average of ozone days) was 39.35 ± 35.74 and 86.49 ± 41.65 µg/m³, respectively. The concentrations of PM_2.5 showed clear seasonal trends, with higher concentrations in winter (83.36 ± 18.66 µg/m³) and lower concentrations in summer (19.85 ± 7.23 µg/m³), however, the seasonal trends of O₃ were different with 103.75 ± 41.77 µg/m³ in summer and 58.59 ± 21.40 µg/m³ in winter. Air mass backward trajectory, analyzing results of potential source contribution function model and concentration weighted trajectory model implied that pollutants from northwestern China contributed significantly to the mass concentration of Shanghai PM_2.5, while pollutants from areas of eastern coastal provinces and South China Sea contributed significantly to the mass level of ozone in Shanghai atmosphere. Mass concentration of twenty-one elements in the PM_2.5 were investigated, and their relationships with O₃ were analyzed. Mass level of ozone had good correlation with that of Ba (r = 0.64, p < 0.05) and V (r = 0.30, p > 0.05), suggesting vehicle emission pollutants contribute to the increasing concentration of ozone in Shanghai atmosphere.     

Ant colonization increased total mercury but reduced methylmercury contents in boreal mires, Northeast China

Soil macroinvertebrates as ecosystem engineers play significant, but largely ignored, roles in affecting mercury (Hg) cycle by altering soil physical-chemical properties. Ant is likely expanded into boreal mires with climate warming, however, its impacts on Hg cycle remained poorly understood. We compared total Hg (THg) and methylmercury (MeHg) contents in soils from antmounds (Lasius flavus) and the nearby ambient in a boreal mire in Northeast China. The present work seeks to unravel factors that controlling MeHg levels in case of ant appearance or absence. The average THg was 179 µg/kg in the ant mound and was 106.1 µg/kg in nearby soils, respectively. The average MeHg was 10.9 µg/kg in the ant mound and was 12.9 µg/kg in nearby soils, respectively. The ratios of MeHg to THg (%MeHg) were 7.61% in ant mounds and 16.75% in nearby soils, respectively. Ant colonization caused THg enrichment and MeHg depletion, and this change was obvious in the 10-20 cm depth soil layer where ants mainly inhabited. Spectrometry characteristics of soil dissolved organic matter (DOM) exert a stronger control than microorganisms on MeHg variation in soils. A structural equation model revealed that the molecular weight of DOM inhibited MeHg irrespective of ant presence or absence, while humification conducive to MeHg significantly in ant mound soils. Microorganisms mainly affected Hg methylation by altering the molecular weight and humification of DOM. We propose that the effects of ant colonization on MeHg rested on DOM feature variations caused by microorganisms in boreal mires.     

Mercury accumulation and dynamics in montane forests along an elevation gradient in Southwest China

Understanding atmospheric mercury (Hg) accumulation in remote montane forests is critical to assess the Hg ecological risk to wildlife and human health. To quantify impacts of vegetation, climatic and topographic factors on Hg accumulation in montane forests, we assessed the Hg distribution and stoichiometric relations among Hg, carbon (C), and nitrogen (N) in four forest types along the elevation of Mt. Gongga. Our results show that Hg concentration in plant tissues follows the descending order of litter > leaf, bark > root > branch > bole wood, indicating the importance of atmospheric Hg uptake by foliage for Hg accumulation in plants. The foliar Hg/C (from 237.0 ± 171.4 to 56.8 ± 27.7 µg/kg) and Hg/N (from 7.5 ± 3.9 to 2.5 ± 1.2 mg/kg) both decrease along the elevation. These elevation gradients are caused by the heterogeneity of vegetation uptake of atmospheric Hg and the variation of atmospheric Hg° concentrations at different altitudes. Organic soil Hg accumulation is controlled by forest types, topographic and climatic factors, with the highest concentration in the mixed forest (244.9 ± 55.7 µg/kg) and the lowest value in the alpine forest (151.9 ± 44.5 µg/kg). Further analysis suggests that soil Hg is positively correlated to C (r² = 0.66) and N (r² = 0.57), and Hg/C and Hg/N both increase with the soil depth. These stoichiometric relations highlight the combined effects from environmental and climatic factors which mediating legacy Hg accumulation and selective Hg absorption during processes of organic soil mineralization.