Multidisciplinary integrated characterization of a native Chlorella-like microalgal strain isolated from a municipal landfill leachate

To date, more than one-hundred taxa of green unicellular coccoid organisms have been wrongly included under the genus Chlorella. This is mainly due to the incomplete characterization resulting from studies that have not adopted and integrated the description of cell morphology, metabolic characteristics and genomic features. In this work, a new native Chlorella-like microalgal strain named “SEC_LI_ChL_1”, is described through a multimethod study. This strain was isolated from a pond where municipal landfil leachate flwed before wastewater treatment. The molecular characterization and the phylogenetic reconstructions based on two different DNA marker regions (i.e. the concatenated SSU and ITS rRNA gene and the complete 18S rRNA gene) were combined with light and transmission electron microscope observations, in addition to the analysis of metabolic traits under four different growing conditions (i.e. autotrophy, heterotrophy, mixotrophy and reduced autotrophy). The two separate phylogenetic analyses highlighted that the strain falls within the Chlorella-Micractinium clade, but with two different placements. According to the morphological-ultrastructural and metabolic analyses, “SEC_LI_ChL_1” shares some features with different Chlorella-like microalgae. Interestingly, two peculiar traits rarely or never previously described in Chlorella-like microalgal strains were observed: the association of the cells with endocellular bacteria, and the presence of doublets (i.e. two-celled microalgae aggregates not due to cell division)

Applicazione delle biotecnologie degradative al risanamento dell'ambiente. Parte III: Sistemi anaerobici ad alta efficienza per la degradazione di composti chimici tossici recalcitranti

Vengono presentate e discusse le pi\uf9 recenti acquisizioni relativamente alla possibilit\ue0 di sfruttamento dei sistemi anaerobici metanogenici nel trattamento di reflui industriali contenenti composti xenobiotici tossici

Use of plant growth-promoting bacteria in phytoremediation protocols for the reclamation of high level As polluted soils

In the present study, the effect of PGP (plant growth-promoting) bacterial inocula, resistant to arsenic, on the efficiency of Pteris vittata - grown on an arsenopyrite contaminated soil - in phytoextracting this metalloid was evaluated. The research was carried out on soil samples collected from an industrial site located in Tuscany (Italy), highly polluted with arsenic and heavy metals (Pb, Fe, Zn and Cd). At first, the characterization of the bacterial community acclimated to As was carried out starting from enrichment cultures in presence of either arsenite or arsenate. Several strains were isolated in pure culture and phylogenetically identified through 16S rRNA analysis. Afterwards, each strain was tested for its capability of growing in presence of high As levels and MIC (Minimum Inhibitory Concentration) values for both arsenite and arsenate were determined. Then, bacterial isolates were checked for the occurrence of As-resistance genotypes, namely ars and aox genes. Three strains - namely Ochrobactrum cytisi E, Pseudomonas putida O and Achromobacter marplatensis P - were chosen for bioaugmentation tests. Phytoremediation trials using Pteris vittata plants grown in As contaminated soil were performed under glasshouse conditions for six months. The persistence of bacterial inocula in soil was assessed through PCR-DGGE analysis

Arsenic Uptake and Translocation by Plants in Pot and Field Experiments

A work undertaken by pot and field experiments to assess the suitability of poplars and ferns for the in-situ, phytoextraction, of a dumping site with residues from the roasting process of arseno-pyrite is reported. The main characteristic of this site is the high content of both the As metalloid and heavy metals (e.g., Al, Fe, Cu, Co, Cr, Pb). Two poplar clones (Populus deltoides ‘Dvina’ and Populus x canadensis ‘Orion’) and Pteris vittata (Chinese brake fern) were planted in the contaminated soil both ex situ in pots and in situ. Plant survival, As accumulation in plant tissues, leaf content of pigments, soluble proteins, activity of catalase and SH-groups in both roots and leaves were evaluated during a 24-month study period. Both poplar and fern plants exhibited an increase in the activity of catalase and SH group contents when grown in the presence of pyrite ashes. The results showed that the co-planting system (arsenic-hyperaccumulator fern Pteris vittata and Populus clones) was suitable for phytoextraction of multi-contaminated dumping sites. Agronomic measures such as irrigation, soil tillage and amendments also seem to be necessary for the successful establishment of poplar trees and ferns in contaminated soils in order to enhance plant growth through the improvement of soil conditions

Isolation of Four Microalgal Strains From the Lake Massaciuccoli: Screening of Common Pollutants Tolerance Pattern and Perspectives for Their Use in Biotechnological Applications

Aquatic ecosystems represent one of the largest reservoirs of phytoplankton accounting for most of the primary production of the Earth. The Lake Massaciuccoli located in Tuscany (Italy) is one of the largest swamps that in ancient times entirely covered the Versilia coastal plain. Despite its peculiar features, especially the eutrophic characteristics, its native microalgal consortia have never been explored up to now. In this work, we isolated and described four autochthonous microalgal strains from different sites in the lake (FB, Idr, CL_Sc, and CL_Ch); the four microalgal strains were identified within the Chlorella sorokiniana clade. We exposed them to ten of the most common or emerging environmental contaminants in order to describe their preliminary response to the tested substances: five metals (As, Fe, Ni, Cu, and Zn), two herbicides (Metolachlor and Sethoxydim), two antibiotics (Ciprofloxacin and Benzylpenicillin) and a non-steroidal anti-inflammatory drug (Ibuprofen). Physiological response of the strains highlighted intraspecific differences; strain CL_Sc was the most tolerant in presence of metals while strain Idr was the most sensitive. All strains were sensitive to sethoxydim and tolerant to metolachlor at all the tested concentrations. Strains FB and Idr were the most sensitive in presence of Ibuprofen while strain CL_Ch was the most sensitive to the highest Benzylpenicillin concentration. Resistance pattern of strain Idr somehow reflects both the phylogenetic and the geographic “isolation” from all other three strains. Finally, optical microscope observation confirmed some differences also in the microalgae morphological aspect. Overall, all the strains showed interesting responses in presence of high concentrations of the tested substances, representing putative interesting candidates for water remediation in wastewater treatment plants

Exploitation of PGPB strains within phytoremediation protocols for the reclamation of soils cantaminated by roasted arsenopyrite residues

This study is aimed at evaluating the effects of bioaugmentation by means of soil addition with arsenic resistant PGPB on the efficiency of phytoextraction capability of the fern Pteris vittata grown on an arsenopyrite contaminated soil, with respect to the metalloid of interest

Hydraulic and chemical mechanisms in the response of pinus pinaster A i t. To conditions of water stress

The increase of temperatures at a global scale constitutes a threaten, among the others, for forest ecosystems, and imposes a deeper comprehension of plant behaviour towards drought stress, in order to better plan a sustainable management of water resources. Young plants of Pinus pinaster A i t. were exposed to prolonged drought stress, during which their xylem ABA concentration, leaf water potential and stomatal conductance were measured at regular intervals on the top branches; the same measurements were taken on a sample of control, non stressed plants. At the same time, plant transpiration rate was measured in response to different ABA concentrations and light regimes. Plant responses to variations of environmental parameters were measured, too: leaf T° vs. atmospheric T°; "E" vs. VPD; "A" vs. (CO2). The data suggest that the plant final response to drought stress, i.e. stomatal closure, is mediated by a combination of hydraulic and hormonal regulation; the mechanical one is triggered on the short period and is more quickly reversible, while the chemical one acts on the medium-long term, when the water stress tends to chronicize

Possible Internalization of an Enterovirus in Hydroponically Grown Lettuce

Several studies have shown that enteric viruses can be transferred onto the surface of vegetables and fruits through spray irrigation, but, recently, reports have suggested viral contamination of vegetables sub-irrigated with reused wastewater. Hydroponic cultures, used to grow ready to eat fresh lettuce, have also been used to study the possibility of viral absorption through roots. This study was conducted to assess a possible risk of viral contamination in lettuce from contaminated water. The leaves of lettuce plants grown in hydroponic cultures where the roots were exposed to water containing Coxsakievirus B2, were analysed for evidence of the virus. The plants and water were sampled at different times and virus was measured using quantitative RT-PCR and infectivity assay. In leaf samples, the lowest observed infective data were lower than the qRT-PCR detection limits, suggesting that free viral RNA or damaged viruses are eliminated rapidly while infectious particles remain stable for a longer time. The obtained data revealed that the leaves were contaminated at a water concentration of 4.11 ± 1 Log Most Probable Number/L (8.03 ± 1 Log GC/L) a concentration observed in contaminated untreated water of wastewater treatment plants. However, the absorption dynamics and whether the virus is inactive in the leaves still remains to be clarified. Nevertheless, this work has practical implications for risk management in using reclaimed water for agricultural use; when irrigated vegetables are destined for raw consumption, virological contamination in water sources should be evaluated