The probabilistic ecological risk assessment using terrestrial toxicity data has been mainly based on microfauna or mesofauna. Soil algae, which are food source for microfauna and mesofauna, may be alternatively used for assessing soil toxicity. However, there are no internationally recommended guidelines for soil algal bioassays, and the collection of algae from the test soils has some limitations. In this study, we suggested the paper-disc method as an easy-to-use alternative. This method has been widely used for testing the antibacterial toxicity of various chemicals in agar media by measuring the diameter of the inhibition zone around the disc. We adapted the paper-disc method for screening the toxicity of copper (Cu) and nickel (Ni) to the soil alga Chlorococcum infusionum using various evaluation endpoints, such as growth zone, chlorophyll fluorescence, and photosynthetic activity. Chlorophyll fluorescence and photosynthetic activity decreased with the increasing concentrations of Cu+2 or Ni+2 contaminated soils. Algal growth zone was analyzed visually and showed similar results to those of chlorophyll fluorescence. The direct ethanol extraction method and indirect culture medium extraction method were similarly effective; however, the former was easier to perform, while the latter might facilitate the analysis of additional endpoints in future studies. Overall, the results suggested that the paper-disc method was not only a user-friendly assay for screening soil toxicity, but also effective due to its association with indirect soil quality indicators.

In this study, adsorption and biodegradation were exploited sequentially to remove the herbicide fenuron, the insecticide carbaryl and the estrogens 17β-estradiol (E2) and 4-tert-octylphenol (OP) from a municipal landfill leachate (MuLL). In the first step, we used spent coffee grounds, almond shells, a biochar and potato dextrose agar to adsorb the compounds spiked in MuLL at a concentration of 1 mg L⁻¹. After only 3 days, any adsorbent removed from MuLL the totality of E2 and OP, averagely more than 95 % of carbaryl and 62 % of fenuron (81 % after 7 days). In the second step, the adsorbents collected from MuLL after 7 days were inoculated with the fungi Bjerkandera adusta and Irpex lacteus, separately. After 7 days, the maximum degradation occurred for OP in any treatment being averagely 78 and 74 % using B. adusta and I. lacteus, respectively. After 15 days, the average percentages of fenuron, carbaryl, E2 and OP degraded were, respectively, 75, 76, 88 and 88 % using B. adusta, and 74, 79, 85 and 89 % using I. lacteus. Residual estrogenicity in the adsorbents, tested with the recombinant yeast assay, was strictly related to residual E2, thus indicating a negligible contribution from the other contaminants and/or degradation products. The 7-day treatment of MuLL with the adsorbents caused a significant abatement of MuLL phytotoxicity on flax (2.5 times seedling elongation with coffee grounds, compared to MuLL) and a huge stimulation of rapeseed respect to water (biomass almost doubled), thus suggesting a possible worthwhile recycling of this wastewater in agriculture.

An investigation on the toxicological assessment of 10 choline chloride (ChCl)-based deep eutectic solvents (DESs) towards four fungi strains and Cyprinus carpio fish was conducted. ChCl was combined with materials from different chemical groups such as alcohols, sugars, acids and others to form DESs. The study was carried out on the individual DES components, their aqueous mixture before DES formation and their formed DESs. The agar disc diffusion method was followed to investigate their toxicity on four fungi strains selected as a model of eukaryotic microorganisms (Phanerochaete chrysosporium, Aspergillus niger, Lentinus tigrinus and Candida cylindracea). Among these DESs, ChCl:ZnCl₂ exhibited the highest inhibition zone diameter towards the tested fungi growth in vitro, followed by the acidic group (malonic acid and p-toluenesulfonic acid). Another study was conducted to test the acute toxicity and determine the lethal concentration at 50 % (LC₅₀) of the same DESs on C. carpio fish. The inhibition range and LC₅₀ of DESs were found to be different from their individual components. DESs were found to be less toxic than their mixture or individual components. The LC₅₀ of ChCl:MADES is much higher than that of ChCl:MAMᵢₓ. Moreover, the DESs acidic group showed a lower inhibition zone on fungi growth. Thus, DESs should be considered as new components with different physicochemical properties and toxicological profiles, and not merely compositions of compounds.

An attempt has been made to isolate, purify and characterize antifouling compound from Streptomyces fradiae PE7 isolated from Vellar estuarine sediment, Parangipettai, South India. The microbial identification was done at species level based on its phenotypic, cell wall and molecular characteristics. Strain PE7 produced high quantity of antifouling compounds in agar surface fermentation when compared to submerged fermentation. In fermentation optimization, wide range of sugars, amino acids, minerals, pH, temperature and NaCl concentration was found to influence the antifouling compound production from the strain PE7. Antifouling compound PE7-C was purified from the crude extract by preparative TLC, and its activity against biofouling bacteria was confirmed by bioautography. Based on the physico-chemical characteristics, the chemical structure of the antifouling compound PE7-C was identified as quercetin (C₁₅H₁₀O₇), a flavonoid class of compound with the molecular weight 302.23 g/mol. The purified quercetin was active against 18 biofouling bacteria with MIC range between 1.6 and 25 μg/ml, algal spore germination and mollusc foot adherence found at 100 μg/ml and 306 ± 19.6 μg ml⁻¹ respectively. The present study, for the first time, reported quercetin from marine-derived Streptomyces sp. PE7 with antifouling activity. This also leads to the repurposing of quercetin for the development of antifouling agent.

Mosquitoes act as vectors of devastating pathogens and parasites, representing a key threat for millions of humans and animals worldwide. The control of mosquito-borne diseases is facing a number of crucial challenges, including the emergence of artemisinin and chloroquine resistance in Plasmodium parasites, as well as the presence of mosquito vectors resistant to synthetic and microbial pesticides. Therefore, eco-friendly tools are urgently required. Here, a synergic approach relying to nanotechnologies and biological control strategies is proposed. The marine environment is an outstanding reservoir of bioactive natural products, which have many applications against pests, parasites, and pathogens. We proposed a novel method of seaweed-mediated synthesis of silver nanoparticles (AgNP) using the spongeweed Codium tomentosum, acting as a reducing and capping agent. AgNP were characterized by UV–Vis spectroscopy, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD). In mosquitocidal assays, the 50 % lethal concentration (LC₅₀) of C. tomentosum extract against Anopheles stephensi ranged from 255.1 (larva I) to 487.1 ppm (pupa). LC₅₀ of C. tomentosum-synthesized AgNP ranged from 18.1 (larva I) to 40.7 ppm (pupa). In laboratory, the predation efficiency of Mesocyclops aspericornis copepods against A. stephensi larvae was 81, 65, 17, and 9 % (I, II, III, and IV instar, respectively). In AgNP contaminated environment, predation was not affected; 83, 66, 19, and 11 % (I, II, III, and IV). The anti-plasmodial activity of C. tomentosum extract and spongeweed-synthesized AgNP was evaluated against CQ-resistant (CQ-r) and CQ-sensitive (CQ-s) strains of Plasmodium falciparum. Fifty percent inhibitory concentration (IC₅₀) of C. tomentosum were 51.34 μg/ml (CQ-s) and 65.17 μg/ml (CQ-r); C. tomentosum-synthesized AgNP achieved IC₅₀ of 72.45 μg/ml (CQ-s) and 76.08 μg/ml (CQ-r). Furthermore, low doses of the AgNP inhibited the growth of Bacillus subtilis, Klebsiella pneumoniae, and Salmonella typhi, using the agar disk diffusion and minimum inhibitory concentration protocol. Overall, C. tomentosum metabolites and spongeweed-synthesized AgNP may be potential candidates to develop novel and effective tools in the fight against Plasmodium parasites and their mosquito vectors. The employ of ultra-low doses of nanomosquitocides in synergy with cyclopoid crustaceans seems a promising green route for effective mosquito control programs.

Pollutants in marine coastal areas are mainly a consequence of anthropogenic inputs, and microorganisms often play a major role in determining the extent of this pollution. Thus, practical and eco-friendly techniques are urgently required in order to control or minimise the pathogenic bacterial problem. The bacterial accumulation of Mytilus galloprovincialis (Lamarck 1919) in the presence or absence of another filter feeder, the demosponge Hymeniacidon perlevis (Montagu 1818) on sewage flowing into the Northern Ionian Sea has been estimated in a laboratory study. On account of the interesting results obtained, we also evaluated the bioremediation capability of the sponges when reared in co-culture with mussels. Specimens of M. galloprovincialis and H. perlevis were collected from the Mar Grande and from the Second Inlet of the Mar Piccolo of Taranto (Northern Ionian Sea, Italy), respectively. In the laboratory, we detected the bacterial abundances in the sewage, in sponge homogenates (both sponges alone and sponges that have been added to sewage with mussels) and in mussel homogenates (both mussels alone and mussels that have been added to sewage with sponges). In the field, we estimated the bacterial concentration in both the seawater within the mussels culture and the seawater collected where mussels were reared in co-culture with sponges. The bacteriological analyses were performed analysing the following parameters: the density of culturable heterotrophic bacteria by spread plate on marine agar, total culturable bacteria at 37 °C on plate count agar and vibrios on thiosulphate–citrate–bile–sucrose–salt (TCBS) agar. Total coliforms, Escherichia coli and intestinal streptococci concentrations were detected by the MPN method. The study demonstrates a higher efficiency of the sponges in removing all the considered bacterial groups compared to the mussels. Due to the conspicuous bacterial accumulation by the sponge, we can conclude that the co-occurrence of the filter-feeder H. perlevis with M. galloprovincialis is a powerful tool in reducing the bacterial load in shellfish culture areas thus playing a role in mitigating the health hazard related to the consumption of edible mussels.

A number of human health effects have been associated with exposure to metal removal fluids (MRFs). Multiple lines of research suggest that a newly identified organism, Mycobacterium immunogenum (MI), appears to have an etiologic role in hypersensitivity pneumonitis (HP) in case of MRFs exposed workers. However, our knowledge of this organism, other possible causative agents (e.g., Pseudomonads), and the microbial ecology of MRFs in general, is limited. In this study, culture-based methods and small subunit ribosomal RNA gene clone library approach were used to characterize microbial communities in MRF bulk fluid and associated biofilm samples collected from fluid systems in an automobile engine plant. PCR amplification data using universal primers indicate that all samples had bacterial and fungal contaminated. Five among 15 samples formed colonies on the Mycobacteria agar 7H9 suggesting the likely presence of Mycobacteria in these five samples. This observation was confirmed with PCR amplification of 16S rRNA gene fragment using Mycobacteria specific primers. Two additional samples, Biofilm-1 and Biofilm-3, were positive in PCR amplification for Mycobacteria, yet no colonies formed on the 7H9 cultivation agar plates. Real-time PCR was used to quantify the abundance of M. immunogenum in these samples, and the data showed that the copies of M. immunogenum 16S rRNA gene in the samples ranges from 4.33 × 10⁴ copy/ml to 4.61 × 10⁷ copy/ml. Clone library analysis revealed that Paecilomyces sp. and Acremonium sp. and Acremonium-like were dominant fungi in MRF samples. Various bacterial species from the major phylum of proteobacteria were found and Pseudomonas is the dominant bacterial genus in these samples. Mycobacteria (more specifically MI) were found in all biofilm samples, including biofilms collected from inside the MRF systems and from adjacent environmental surfaces, suggesting that biofilms may play an important role in microbial ecology in MRFs. Biofilms may provide a shield or sheltered microenvironment for the growth and/or colonization of Mycobacteria in MRFs.

As an eco-friendly management method, biological control of postharvest diseases, utilizing antagonistic yeasts, is a research topic receiving considerable attention. Detailed knowledge on the biology of yeast antagonists is crucial when considering their potential application and development as biocontrol products. Changes in the growth form, such as single-cell to pseudohyphae, have been associated with the mode of action in postharvest biocontrol yeasts. In this study, the antagonistic yeast, Candida diversa, reversibly shifted from a single-cell morphology on yeast peptone dextrose (YPD) medium with 2 % agar to a pseudohyphal morphology on YPD with 0.3 % agar. The tolerance of the pseudohyphal form to heat and oxidative stresses, as well as the biocontrol efficacy against Botrytis cinerea on apple and kiwifruit stored at 25 and 4 °C, was significantly higher as compared to the single-cell form. This study provides new information on the ability of C. diversa to change its morphology and the impact of the morphology shift on stress tolerance and biocontrol performance.