Impact of a native Streptomyces flavovirens from mushroom compost on green mold control and yield of Agaricus bisporus

ABSTRACT

Thirty-five actinobacterial isolates, obtained from button mushroom (Agaricus bisporus) substrates (i.e., compost in different phases of composting, black peat or casing layer) in Serbia in 2014–2016 were tested in vitro against the causal agents of green mold in cultivated mushroom. Out of six most promising isolates, A06 induced 42.4% in vitro growth inhibition of Trichoderma harzianum T54, and 27.6% inhibition of T. aggressivum f. europaeum T77. The novel strain A06 was identified as Streptomyces flavovirens based on macroscopic and cultural characteristics and 16S rDNA sequence and used in mushroom growing room experiments. Actinobacteria had no negative influence on mycelial growth of the cultivated mushroom in compost in situ. Isolate S. flavovirens A06 enhanced mushroom yield significantly, up to 31.5%. The A06 isolate was more efficient in enhancing yield after inoculation with the compost mold T. aggressivum (26.1%), compared to casing mold T. harzianum (8%). Considering disease incidence, actinobacteria significantly prevented green mold in compost caused by T. aggressivum (6.8%). However, fungicide prochloraz-Mn had a more significant role in reducing symptoms of casing mold, T. harzianum, in comparison with actinobacteria (24.2 and 11.8%, respectively). No significant differences between efficacies of S. flavovirens A06 and the fungicide prochloraz-Mn against T. aggressivum were revealed. These results imply that S. flavovirens A06 can be used to increase mushroom yield and contribute to disease control against the aggressive compost green mold disease caused by Trichoderma aggressivum.     

Fullerol C<Subscript>60</Subscript>(OH)<Subscript>24</Subscript> nanoparticles and mycotoxigenic fungi: a preliminary investigation into modulation of mycotoxin production

Increased use of fullerols in various fields and expected increase of their environmental spread impose the necessity for testing fullerol nanoparticles (FNP) effects on microbiota. There is little information available on the interaction of mycotoxigenic fungi and FNP, despite FNP having a great potential of modifying mycotoxin production. Namely, FNP exhibit both ROS-quenching and ROS-producing properties, while oxidative stress stimulates mycotoxin synthesis in the fungi. In order to shed some light on the extent of interaction between FNP and mycotoxigenic fungi, the effects of fullerol C₆₀(OH)₂₄ nanoparticles (10, 100, 1000 ng/mL) on mycelial growth, aflatoxin production and oxidative stress modulation in an aflatoxigenic strain of Aspergillus flavus (NRRL 3251) during 168 h of incubation in a liquid culture medium were examined. FNP slightly reduced mycelial biomass weight, but significantly decreased aflatoxin concentration in media. Lipid peroxide content, superoxide dismutase, catalase and glutathione peroxidase activities suggest that FNP treatments hormetically reduced oxidative stress within fungal cells in turn suppressing aflatoxin production. These findings contribute to the assessment of environmental risk and application potential of fullerols.     

Quantification of sources of PCBs to the atmosphere in urban areas: A comparison of cities in North America, Western Europe and former Yugoslavia

We present estimated emission source strengths of seven polychlorinated biphenyl (PCB) congeners for Banja Luka, a city that was affected by the civil war in Bosnia and Hercegovina (former Yugoslavia) in the 1990s. These emission estimates are compared to PCB emission rates estimated for the cities of Zurich, Switzerland, and Chicago, USA using an approach that combines multimedia mass balance modeling and measurement data. Our modeled per-capita emission estimates for Banja Luka are lower by a factor of ten than those for Zurich and Chicago, which are similar. This indicates that the sources of PCB emissions in Banja Luka are likely to be weaker than in the Western European and North American cities which show relatively high PCB emissions. Our emission rates from the three cities agree within a factor of ten with emission estimates from a global PCB emission inventory derived from production and usage estimates and emission factors.     

Extending the use of air quality indices to reflect effective population exposure

Although there are tendencies to develop a single common index which would describe an overall air quality status within an area, constructed from a choice of measurements of individual pollutants, indices describing individual pollutants themselves have several potentials which can be used in ways which are not possible with pollutant concentrations. On the case of Belgrade, Serbia, we investigated possibilities of using such indices for comparisons between pollutants, characterization of monitoring sites, and extending their use to include elements of population exposure. A methodology of adjusting the results obtained at monitoring stations located in severe pollution conditions, like street canyons, is proposed and used.     

Reference Point Approach for Multi-objective Assessment and Reduction of Ground-Level O<Subscript>3</Subscript> Air Quality Monitoring Network in Vojvodina Province,Serbia

A monitoring network of ground-level ozone (O₃) concentration levels in Vojvodina Province, Serbia, has been established in several phases, resulting in nine sampling sites (monitoring stations). Because maintenance of a monitoring network is financially very demanding, identifying potentially redundant ozone sites and reducing the network to a cost-effective and functional one are challenging and complex tasks. To provide an easily applicable but reliable analytical framework that will allow decision-makers and other stakeholders to identify redundant ground O₃ monitors, the reference point approach, presented by Cetinkaya and Harmancioglu (Journal of Hydrology, 2014), is adopted for a multi-objective assessment of the O₃ monitoring network. The evaluation process of the stations’ performance and their ranking is implemented in several phases. Firstly, a comprehensive set of 13 performance attributes is defined and associated with location and environmental criteria, followed by defining the set of alternatives. Next, all required attribute data are collected and stations are evaluated using the reference point approach. Finally, verification of the results is performed by aggregation of ranks obtained using the ideal point multi-criteria methods compromise programing and Technique for Order of Preference by Similarity to Ideal Solution. The aggregation process is performed using the Borda count and Kemeny social choice theory methods. Results indicate that the number of stations can be significantly reduced by 67%. Also, selection of the three best performing stations enabled identification of a core network that is expected to be functionally and financially sustainable under growing environmental and economic pressure.     

Polycyclic aromatic hydrocarbons in air on small spatial and temporal scales – I. Levels and variabilities

Polycyclic aromatic hydrocarbons (PAHs) were measured together with inorganic air pollutants at two urban sites and one rural background site in the Banja Luka area, Bosnia and Hercegovina, during 72 h in July 2008 using a high time resolution (5 samples per day) with the aim to study the spatial and temporal variabilities and to explore the significance of averaging effects inherent to 24 h-sampling. Measurement uncertainty was quantified on basis of three independent side-by-side samplers, deployed at one of the sites.PAH abundances in the urban and rural environments differed largely. Levels at the urban sites exceeded the levels at the rural site by >100%. The discrepancy was largely dominated by emission of 3–4 ring PAHs in the city, while 5–6 ring PAHs were more evenly distributed between city sites and the hill site. During the night a higher fraction of the semivolatile PAHs might have been stored in the soil or sorbed to surfaces. PAH patterns were undistinguishable across the three sites. However, concentrations of more particle-associated substances differed significantly between the urban sites than between one of the urban sites and the rural site (3σ uncertainty). Time-averaging (on a 24 h-basis) would have masked the significant inter-site differences of half of the substances which were found at different levels (on a 4 h-basis).     

Freshwater systems and ecosystem services: Challenges and chances for cross-fertilization of disciplines

Freshwater ecosystems are among the most threatened in the world, while providing numerous essential ecosystem services (ES) to humans. Despite their importance, research on freshwater ecosystem services is limited. Here, we examine how freshwater studies could help to advance ES research and vice versa. We summarize major knowledge gaps and suggest solutions focusing on science and policy in Europe. We found several features that are unique to freshwater ecosystems, but often disregarded in ES assessments. Insufficient transfer of knowledge towards stakeholders is also problematic. Knowledge transfer and implementation seems to be less effective towards South-east Europe. Focusing on the strengths of freshwater research regarding connectivity, across borders, involving multiple actors can help to improve ES research towards a more dynamic, landscape-level approach, which we believe can boost the implementation of the ES concept in freshwater policies. Bridging these gaps can contribute to achieve the ambitious targets of the EU’s Green Deal.     

Approach of Decision Making Based on the Analytic Hierarchy Process for Urban Landscape Management

This paper proposes a two-stage group decision making approach to urban landscape management and planning supported by the analytic hierarchy process. The proposed approach combines an application of the consensus convergence model and the weighted geometric mean method. The application of the proposed approach is shown on a real urban landscape planning problem with a park-forest in Belgrade, Serbia. Decision makers were policy makers, i.e., representatives of several key national and municipal institutions, and experts coming from different scientific fields. As a result, the most suitable management plan from the set of plans is recognized. It includes both native vegetation renewal in degraded areas of park-forest and continued maintenance of its dominant tourism function. Decision makers included in this research consider the approach to be transparent and useful for addressing landscape management tasks. The central idea of this paper can be understood in a broader sense and easily applied to other decision making problems in various scientific fields.     

Barriers for implementation of “waste to energy” in developing and transition countries: a case study of Serbia

The aim of this study is to assess boundaries and potential for implementation of waste-to-energy projects in developing and transition countries in order to give realistic future directions for waste-to-energy initiatives. For this purpose, Serbia is taken as an example. In order to highlight the most important issues, which hinder the feasibility of waste-to-energy projects, analysis of the status quo of Serbian municipal solid waste management is performed. In addition, based on the current political and social status of the country, the most important factors that need to be solved as a precondition to waste-to-energy projects are defined. This analysis revealed that aside from technical factors, sociopolitical and cultural obstacles must be eliminated as a prerequisite for successful implementation of waste-to-energy projects. We define the most sustainable pathway for waste-to-energy initiatives in Serbia as well as other similar developing and transition countries, which can complement development of the entire waste management system.     

Assessing the impact of weather events at mid-latitudes on the atmospheric transport of chemical pollutants using a 2-dimensional multimedia meteorological model

We investigate the long-range transport potential (LRTP) of five different classes of hypothetical chemical pollutants (volatile, multimedia, semivolatile, particle-associated and hydrophilic) during a low pressure weather event using a novel 2 (x- and z-axis)-Dimensional Multi-Media Meteorological Model (2D4M). The atmosphere (z-axis) is described by three atmospheric layers, where two layers constitute the boundary layer and the third layer the free troposphere. The 2D4M can describe distinct weather events on a regional scale and calculate the LRTP of chemicals as a function of time during these events. Four weather factors are used to model weather events and their influence on the atmospheric transport of chemicals: (1) temperature, (2) wind speed and mixing dynamics of the troposphere, (3) hydroxyl radical concentrations and (4) precipitation. We have modeled the impact of variability in each of these factors on LRTP of pollutants during a front event associated with a low pressure period that interrupts a dominant high pressure system. The physico-chemical properties of the pollutant determine which specific weather factors contribute most to variability in transport potential during the event. Volatile and multimedia chemicals are mainly affected by changing atmospheric mixing conditions, wind speeds and OH radical concentrations, while semivolatile substances are also affected by temperature. Low-vapor-pressure pollutants that are particle-associated, and water-soluble pollutants are most strongly affected by precipitation. Some chemical pollutants are efficiently transported from the boundary layer into the upper troposphere during the modeled low pressure event and are transported by much higher wind speeds than in the boundary layer. Our model experiments show that the transport potential of volatile, multimedia and semivolatile compounds is significantly increased during a front event as a result of efficient tropospheric mixing and fast wind speeds in the upper troposphere, whereas low-volatility and hydrophilic chemicals are largely scavenged from the atmosphere. In future LRTP assessment of chemical contaminants as required by the Stockholm Convention and the convention on long-range transboundary air pollution, it is therefore advised to prioritize volatile, multimedia and semivolatile chemicals that are identified in initial screening.