Effect of farm characteristics and practices on hygienic quality of ovine raw milk used for artisan cheese production in central Italy

A survey on ovine dairy farms directly transforming own‐produced milk, in the Italian Marche region, was carried out to assess flock and milking practices that may influence milk hygienic‐sanitary conditions. A census survey established that 24 dairy farms were located in this region. Bulk milk samples were collected throughout the milking period in each dairy farm in 2013. Analyzed variables were: (i) chemical parameters such as fat, protein and lactose content, dry matter and pH; and (ii) total bacterial (TBC) and somatic cell counts (SCC). Chemical parameter values were in agreement with published data while, geometric mean (GM) log₁₀ SCC was 5.91 and TBC GM was 57 978 colony forming units/mL, in compliance with Eropean Union criteria. A positive correlation was found between SCC and TBC when GMs of all farm data were considered (Spearman's rho = 0.7925; P = 0.0001). Statistical analysis did not show significant correlation between SCC or TBC GM and dairy farm principal characteristics. Although SCC levels detected in the present study should suggest the need to implement mastitis control programs, Marche's dairy sheep flocks revealed a good hygienic condition level. This is an important aspect in implementing safety for end users of the final product.     

Fly ashes as an emendment in cultivated soils

The effect of different percentages of two fly ashes, derived from the combustion of coals from Poland (PO) and South Africa (SA), on organic N mineralization and nitrification in two different soils, was investigated. Following the addition of 2, 5, and 10% (w/w) PO and SA, the N mineralization constant K ₁ decreased in the soil low in organic matter content. The addition of the same percentages of the two fly ashes to the soil higher in organic matter content gave contrasting results. When nitrification was taken into account, the nitrification constant K₂ increased, following the addition of 2, 5, and 10% (w/w) PO and SA to the two soils. The most noticeable exception was the addition of 10% SA to the soil low in organic matter content, where K ₂ decreased.     

Shrinkage of artificially dried soil samples collected at different depths in a clay soil

Quantitative variations of shrinkage patterns in soil samples collected at different depths along a “V” shaped crack were estimated. Size distribution of cracks and size distribution of clods were also determined. Slight differences were found in the values of total shrinkage but at increasing depth cracks became larger and the number of dimensional size classes in which cracks were distributed increased. In samples collected at 0-5 cm, and 25-30 cm the largest cracks belonged to the dimensional class 0.8-1 mm while in the deepest samples (65-70cm) the width of largest cracks was 2.0 mm. Along the profile there was a regular increase of clods of the largest size (> 20 mm) from 25 %to more than 50 % for samples collected at the soil surface and those collected at 65-70 cm, respectively.     

Cadmium occurrence in soil organic matter and its availability to wheat seedlings

Experiments were performed concerning the influence of soil organic matter on Cd availability to wheat seedlings. Cadmium added to soil was bound by alkali soluble humic substances through linkages so strong that it was not removable by seedlings under toxic limit. Cadmium linked by organic matter was principally found in fulvic acids, and after polyamide chromatography of the latter, all fulvic Cd was completely recovered in first fraction which contained the major part of aminoacid compounds. These findings suggest that interactions between Cd and proteic substances, frequently reported in studies on animal tissues, are active in soil too.     

Paediatric HUS Cases Related to the Consumption of Raw Milk Sold by Vending Machines in Italy: Quantitative Risk Assessment Based on Escherichia coli O157 Official Controls over 7 years

A quantitative risk assessment (RA) was developed to estimate haemolytic‐uremic syndrome (HUS) cases in paediatric population associated with the consumption of raw milk sold in vending machines in Italy. The historical national evolution of raw milk consumption phenomenon since 2008, when consumer interest started to grow, and after 7 years of marketing adjustment, is outlined. Exposure assessment was based on the official Shiga toxin‐producing Escherichia coli O157:H7 (STEC) microbiological records of raw milk samples from vending machines monitored by the regional Veterinary Authorities from 2008 to 2014, microbial growth during storage, consumption frequency of raw milk, serving size, consumption preference and age of consumers. The differential risk considered milk handled under regulation conditions (4°C throughout all phases) and the worst time–temperature field handling conditions detected. In case of boiling milk before consumption, we assumed that the risk of HUS is fixed at zero. The model estimates clearly show that the public health significance of HUS cases due to raw milk STEC contamination depends on the current variability surrounding the risk profile of the food and the consumer behaviour has more impact than milk storage scenario. The estimated HUS cases predicted by our model are roughly in line with the effective STEC O157‐associated HUS cases notified in Italy only when the proportion of consumers not boiling milk before consumption is assumed to be 1%. Raw milk consumption remains a source of E. coli O157:H7 for humans, but its overall relevance is likely to have subsided and significant caution should be exerted for temporal, geographical and consumers behaviour analysis. Health education programmes and regulatory actions are required to educate people, primarily children, on other STEC sources.     

Heavy metal uptake by wheat seedlings grown in fly ash-amended soils

A bioassay technique was used to investigate heavy metals uptake by wheat seedlings grown in fly ash-amended soils. No negative effect of fly ash on the growth of wheat seedlings was found. The addition of the fly ash generally decreased the heavy metal concentration in the wheat seedlings. The total accumulation largely depended on the soil characteristics. The variation in the soil pH induced by the fly ash treatment could be considered the most important parameter that influenced heavy metals uptake. In the soil with a higher increase of pH (2 units) total accumulation of heavy metals decreased with increasing fly ash addition. In the other soils where the pH variation was lower (0.4 units), total accumulation of some heavy metals increased. These obtained data provide useful information which is required before the agronomic use of fly ash can be recommended in Italian soils.     

The influence of phosphate fertilizers on Cd solubility in soil

We investigated the influence of monoammonium phosphate (MAP) and diammonium phosphate (DAP) on the adsorption process of Cd by two typic soils. The phosphate induced variations in the pH values of soil-Cd suspensions, drastically influenced the solubility of the heavy metal in the two soils. MAP decreased the amount adsorbed while DAP increased the quantity fixed by the soil. The effect was particularly remarkable in the soil with low content of organic matter (Lamporecchio soil) where the addition of DAP caused the precipitation of the heavy metal. In the organic soil (Orentano soil) the effect of phosphate was less evident because of the high buffering capacity of this soil, rich in colloidal fractions.     

Phytoremediation of a multi contaminated soil: mercury and arsenic phytoextraction assisted by mobilizing agent and plant growth promoting bacteria

Purpose

The possibility of using chemical and microbial additives to enhance the phytoextraction of mercury (Hg) and arsenic (As) from a multi-contaminated soil could be very effective, leading to a significant saving in terms of time and costs of the reclamation. The aim of this study was to evaluate the efficacy of the addition of (i) thiosulfate and (ii) metal-tolerant bacteria isolated from the polluted soil having plant growth promotion (PGP) potential to perform As and Hg phytoextraction by Brassica juncea and Lupinus albus.

Materials and methods

A collection of 13 bacterial isolates able to tolerate As and Hg was obtained from the contaminated soil, identified by partial 16S rRNA gene sequencing and tested in vitro for PGP activities. The most promising strains were further tested in vivo for the evaluation of plant growth ability and rhizocompetence on model plants. Pot experiments were conducted in microcosms, with polluted soil vegetated with B. juncea and L. albus. Ammonium thiosulfate and potassium dihydrogen phosphate were used as mobilizing agents, together with a bacterial consortium composed by the most promising PGP isolates.

Results and discussion

Thirteen indigenous metal-tolerant bacterial strains were isolated, and their in vitro characterization highlighted their great potential in assisting the phytoremediation process; most of them tolerated both trace elements and showed, at the same time, multiple PGP traits. The results were confirmed in vivo on model plants and lead to the selection of the most promising PGP strains to be applied in microcosm-scale phytoextraction experiments. Thiosulfate addition significantly increased the mobilization of both elements, promoting bioavailability and phytoextraction. When a selected bacterial consortium was supplemented in addition to thiosulfate, the efficacy of the phytoaccumulation was increased up to 85 % for As and up to 45 % for Hg.

Conclusions

The use of the common fertilizer thiosulfate appeared to have great potential in phytoextraction practices since it was able to facilitate the uptake by plants of both Hg and As. Moreover, the application of a consortium of indigenous PGP bacteria (PGPB) produced a further positive effect on the plant biomass, supporting and enhancing the phytoextraction strategy, thus demonstrating their potential in a microbe-assisted phytoremediation intervention.