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Abstract The research studied the effects of organic vs. conventional management of soil quality and tomato yield quality, cultivated in a geogenic arsenic contaminated soil. The chemical and biochemical properties were analyzed to evaluate soil quality, arsenic mobility and its phyto-availability, as well as arsenic accumulation in the tomato plant tissues and if tomatoes cultivated in arsenic rich soil represents a risk for human health. A general improvement of tomato growth and soil quality was observed in the organic management, where soil organic carbon increased from 1.24 to 1.48% and total nitrogen content. The arsenic content of the soil in the organic management increased from 57.0 to 65.3 mg kg−1, probably due to a greater content of organic matter which permitted the soil to retain the arsenic naturally present in irrigation water. An increase of bioavailable arsenic was observed in the conventional management compared to the organic one (7.05 vs 6.18 mg kg−1). The bioavailable form of metalloid may affect soil microbial community structure assessed using El-FAME analysis. The increase of the total arsenic concentration in the organic management did not represent a stress factor for soil microbial biomass carbon (Cmic), which was higher in the organic management than in the conventional one (267 vs. 132 μg Cmic g−1). Even if the organic management caused an increase of total arsenic concentration in the soil due to the enhanced organic matter content, retaining arsenic from irrigation water, this management mitigates the arsenic uptake by tomato plants reducing the mobility of the metalloid. Highlights • An improvement of tomato and soil health was observed in the organic system. • Arsenic 56–75 mg kg−1 in soil didn’t represent a stress for the microbial community. • The organic system mitigates arsenic accumulation in plant tissues. • Tomato fruits grown in arsenic rich soil do not represent a risk for human health. [ABSTRACT FROM AUTHOR]

The present work was aimed at isolating and identifying the main members of the mycobiota of a clay soil historically contaminated by mid- and long-chain aliphatic hydrocarbons (AH) and to subsequently assess their hydrocarbon-degrading ability. All the isolates were Ascomycetes and, among them, the most interesting was Pseudoallescheria sp. 18A, which displayed both the ability to use AH as the sole carbon source and to profusely colonize a wheat straw:poplar wood chip (70:30, w/w) lignocellulosic mixture (LM) selected as the amendment for subsequent soil remediation microcosms. After a 60 d mycoaugmentation with Pseudoallescheria sp. of the aforementioned soil, mixed with the sterile LM (5:1 mass ratio), a 79.7% AH reduction and a significant detoxification, inferred by a drop in mortality of Folsomia candida from 90 to 24%, were observed. However, similar degradation and detoxification outcomes were found in the non-inoculated incubation control soil that had been amended with the sterile LM. This was due to the biostimulation exerted by the amendment on the resident microbiota, fungi in particular, the activity and density of which were low, instead, in the non-amended incubation control soil. [ABSTRACT FROM AUTHOR]

The increasing demand of plant oils for biodiesel production has highlighted the need for alternative strategies based either on non-food crops or agro-industrial wastes that do not compete with food and feed production. In this context, the combined use of wastewater and oleaginous microorganisms could be a valuable production option. Ricotta cheese whey (RCW), one of the major byproducts of the dairy industry, is produced in very high and steadily increasing amounts and, due to its high organic load, its disposal is cost-prohibitive. In the present study, in order to assess the adequacy of RCW as a growth medium for lipid production, 18 strains of oleaginous yeasts were investigated in shaken flask for their growth and lipid-producing capabilities on this substrate. Among them, Cryptococcus curvatus NRRL Y-1511 and Cryptococcus laurentii UCD 68-201 adequately grew therein producing substantial amounts of lipids (6.8 and 5.1 g L − 1 , respectively). A high similarity between the percent fatty acid methyl esters (FAME) composition of lipids from the former and the latter strain was found with a predominance of oleic acid (52.8 vs. 48.7%) and of total saturated fatty acids (37.9 vs. 40.8%). The subsequent scale transfer of the C. laurentii UCD 68-201 lipid production process on RCW to a 3-L STR led to significantly improved biomass and total lipid productions (14.4 and 9.9 g L − 1 , respectively) with the biodiesel yield amounting to 32.6%. Although the C. laurentii FAME profile was modified upon process transfer, it resembled that of the Jatropha oil, a well established feedstock for biodiesel production. In conclusion, C. laurentii UCD 68-201, for which there is very limited amount of available information, turned out to be a very promising candidate for biodiesel production and wide margins of process improvement might be envisaged. [ABSTRACT FROM AUTHOR]

• SCG are colonised by Trichoderma atroviride and other microorganisms. • T. atroviride is antagonist against damping off pathogens by in vitro tests. • Peat-10%SCG substrate is suppressive against Phytophthora nicotianae. • Peat-10%SCG + T. atroviride decreases damping off of cress. Espresso spent coffee grounds (SCG) are a high-value organic waste material often reported as a suitable soil amendment in horticulture. The aim of the present work was to evaluate the suppressiveness characteristics of SCG by the analysis of antagonistic microorganisms colonizing SCG and by a bioassay with cress grown on peat amended with 10% SCG and infested with the damping off causal pathogens Sclerotinia sclerotiorum and Phytophthora nicotianae. Among culturable microorganisms, mesophilic bacteria were the main forms colonizing SCG followed by actinomycetes. Fungal species isolated from SCG were represented by Trichoderma atroviride and, at a lesser extent, T. citrinoviride and Aspergillus sp. In vitro assays revealed that sterilized SCG were able to strongly inhibit mycelial growth of both S. sclerotiorum and P. nicotianae. By contrast, T. atroviride representative isolates Ta3 and Ta4, isolated from SCG, were able to rapidly colonise sterilized SCG. This result indicates that this species is insensitive to antimicrobial compounds present in SCG and are probably involved in the mechanism of soilborne pathogen suppression. Both Trichoderma isolates were characterised for their antagonistic activity. In dual culture assays, T. atroviride Ta3 and Ta4 inhibited the mycelial growth of both S. sclerotiorum and P. nicotianae and produced toxic volatile and non-volatile metabolites, having complementary inhibitory effects on growth of the target pathogens. Results from the bioassay revealed that sterilized peat-SCG substrate significantly reduced damping-off of cress due to P. nicotianae but failed to suppress that caused by S. sclerotiorum. When the sterilized peat-SCG substrate was enriched with T. atroviride Ta3 and Ta4 a consistent decrease of damping off caused by the two pathogens was recorded. SCG was found to be a valuable source of nutrients and not phytotoxic on cress at 10% peat substitution rate, but decreased plant growth. Present results indicate that SCG, a suitable component of mixed-peat or fortified substrates, are capable to provide disease suppression and represents an optimal substrate to support growth and activity of antagonistic Trichoderma. [ABSTRACT FROM AUTHOR]