Critical metals play a crucial role in advancing sustainable energy technologies, with their demand steadily increasing due to the global push for a circular economy. At present, critical metals are primarily extracted from mineral resources, but critical metal-contaminated soils could often be considered as an alternative source of these elements. There is a growing need for remediation approaches that not only decontaminate soils but also recover valuable metals, thereby aligning with the principles of a circular economy. This review aims to suggest soil remediation strategies able to tackle critical metals contamination, particularly those capable of extracting these elements (dual-purpose technologies). Existing studies indicate that critical metal-contaminated soils are commonly found near mining sites, but their increasing use is spreading these elements into the whole environment. Considering nickel as an example of critical metal, we examine some consolidated technologies which, in addition to remediation, enable the recovery of this critical metal from the soil. Phytomining demonstrated significant potential in extracting nickel from contaminated soils. Electrokinetic treatment and soil washing can be considered as a promising methodology to clean up soils, also facilitating nickel recovery.

Guayule (Parthenium argentatum A. Gray) is a desert perennial plant species native to the southwest regions of the United States and to the northern Mexico. Studies on the adaptation of guayule to the Mediterranean climate are currently underway, but most of them are related to the production of natural rubber and other secondary metabolites such as resin. Guayule has the potential of becoming an agronomic crop in saline soils, but its salinity tolerance level is not defined yet, as well as its eventual capacity of salt uptake and/or detoxification. This work aimed at investigating the influence of high and extremely high concentrations of sodium chloride (NaCl) on morphophysiological and biochemical features of guayule. Guayule plants (about 3.5 months old) were grown in hydroponics with increasing NaCl concentrations (from 1–2.5 to 40 g L−1) under controlled conditions. Growth and photosynthetic parameters revealed an effective reduction in plant performance from 10 to 15 g L−1 NaCl. After the addition of 40 g L−1 NaCl, sodium (Na) concentration in leaves, stem and roots increased compared to the control, with a high translocation and bioconcentration factor. The growth and physiological parameters analysed showed that guayule underwent the specific ionic effects of salt stress at 10–15 g L−1 (170–257 mM) and survived under hypersalinity conditions of 35–40 gL−1 NaCl (> 600 mM). This study identifies a series of morphophysiological and biochemical parameters useful to test plant response to high salt stress in relatively short time (acute exposure). In this fast screening, guayule proved to be a halotolerant species with potential for phytomanagement and/or phytodesalinization of arid and semiarid environments affected by high salinity.

High and worldwide increasing salinity is impacting crop growth and yield, especially in drylands. In arid environments, the water scarcity has induced to irrigate with reused sanitized wastewaters. In drylands, large and increasing volumes (>50 billion m3 year-1) of water potentially suitable for irrigation might originate from underground formations alongside oil and gas reservoir. The extremely high salinity (mainly due to sodium chloride, NaCl) of such water is the major limiting factor for its reuse as irrigation water. In these areas, non-food industrial crops adapted to drought and marginal lands, if tolerant to excess salt, represent a sustainable solution. Young plants of castor (Ricinus communis L.) were grown in hydroponics under a wide range of high and increasing levels of NaCl (from 2.5 to 25 g L-1, or 43 to 428 mM) for 24 days; the effects on growth, morphophysiological traits, photosynthesis, nutrients and sodium (Na) distribution and balance were studied. Plants began to show functional impairments in presence of 15 g L-1 (257 mM) NaCl, recovered at 20 g L-1 NaCl and went on growing and absorbing Na up to 25 g L-1 NaCl. The uptake of Na and its distribution in the plant tissues differently altered the concentration of major cations, while maintaining their relative content. The relationships among morphometric, physiological and chemical traits explained the castor tolerance to extreme saline concentrations. The high values of Na translocation and bioconcentration factors give good prospects for its bioaccumulation and removal by castor in applications of phytomanagement and/or phytodesalinization.

Hypersaline waters contaminated with crude oil represent a major obstacle for phytoremediation, as few plant species tolerate both high salinity and hydrocarbon toxicity. In this study, the halophyte Halocnemum strobilaceum (Pallas) M. Bieb. was grown hydroponically in hypersaline solutions (50 and 80 g L-1 NaCl) containing crude oil (600 mg L-1). The plant was inoculated with endophytic bacteria isolated in a previous step from its root and selected for salt tolerance and hydrocarbon-degrading potential. The plant behaviour was assessed through growth and photosynthetic performance, while the degradation of hydrocarbons (C < 12 and C > 12) was monitored over time. At 50 g L-1 NaCl, crude oil reduced the plant growth by 60%, but inoculation with endophytic bacteria mitigated this decline, demonstrating their positive influence under combined salt and hydrocarbon stress. At 80 g L-1 NaCl, neither plant biomass nor chlorophyll fluorescence was significantly affected by crude oil, with or without bacterial inoculation, consistent with the strong intrinsic salt tolerance of H. strobilaceum, which likely buffered additional stress inputs. Metagenomic analyses revealed distinct root-associated microbial communities under different treatments, suggesting synergistic plant-microbe interactions that enhanced photosynthetic efficiency and metabolic stability. The presence of endophytes accelerated the degradation of aliphatic hydrocarbons (C10-C40) at both salinity levels. These findings highlight the potential of endophytic bacteria to enhance resilience in H. strobilaceum and its phytoremediation capacity, offering a promising nature-based approach for the sustainable treatment of highly saline, crude oil-contaminated industrial waters.

Hydrogen is a fundamental electron donor in diverse microbial metabolisms and it is considered the energetic currency exchanged within microbial communities in anaerobic environments. Hydrogen is also the major actor in the transition to alternative low-carbon energy sources, primarily due to its dual role as energy source and energy carrier and to the production of water as a byproduct of its combustion. The geological storage of hydrogen gas produced from diverse sources in stable terrestrial reservoirs, known also as Underground Hydrogen Storage (UHS), is a key prerequisite to decouple production from utilization. UHS targets include depleted porous natural gas reservoirs, salt caverns and deep aquifers. Studies carried out in the past 30 years have unveiled a large subsurface ecosystem able to interact with the geochemical cycles and volatiles present in Earth’s crust. When hydrogen is stored underground, the microbial communities present in situ can interact with it, consuming it as electron donor, potentially producing undesired metabolic byproducts capable of affecting the success of UHS operations. Additionally, subsurface microbial communities might impact the geological production, migration and accumulation of hydrogen in natural reservoirs. Here, we review the current state of knowledge in hydrogenotrophic metabolisms capable of affecting UHS operations and natural hydrogen prospecting, and discuss how the microbiology of natural hydrogen-rich springs can be used as analog to model the state space of hydrogen operations. We discuss our current knowledge of the limits of life in the context of hydrogen economy, and the complex trophic network that hydrogen might sustain in the subsurface. While energy demands increase globally, the ability to effectively operate geological hydrogen storage and identify natural hydrogen deposits will become a key prerequisite to reduce the global carbon footprint. Understanding the potential for microbes to interact with hydrogen in the subsurface is therefore at the forefront of the ecological transition.

Innovative approaches to harness endophytic bacteria for promoting plant growth and tackling environmental challenges, such as salinity and pollution, have gained recognition. Halophytic plants, which naturally thrive in saline environments, offer promising prospects for phytoremediation, particularly in addressing the treatment of produced waters (PWs) from Oil Gas plants, characterized by their high salinity and lingering hydrocarbon residues. Halocnemum strobilaceum (Pall.) M. Bieb was selected as the plant species, and associated endophytic bacteria were carefully isolated. These endophytes were derived from the roots of the same plant species that had been cultivated for 18 months in hydroponic saline conditions enriched with 600 ppm of crude oil. The chosen bacterial strains underwent rigorous characterization for their plant growth-promoting traits and were subsequently employed as inoculants. The plants were cultivated in a controlled greenhouse environment under various conditions, including exposure to 50 g L−1 of sodium chloride (NaCl) and 600 ppm of crude oil, and with and without the endophytes’ inoculation. Results unveiled a compelling outcome: the introduction of a hydrocarbons’ mixture into the nutrient solution containing 50 g L−1 NaCl led to a significant reduction in plant growth (three folds), however, the endophytic bacteria inoculation mitigated this reduction, underscoring their constructive influence on plant growth. This phenomenon could be attributed to the synergistic interaction between plants and bacteria, which enhanced the efficiency of the photosynthetic machinery.

Plant growth-promoting bacteria (PGPB) are vital for enhancing plant growth, productivity, and sustainability in agriculture, also addressing food security challenges. The plant growth-promoting (PGP) potential of ten bacterial strains, isolated from a cultivated field in southern Italy, was characterized with biochemical and molecular analyses and plant growth-promoting activity was tested on two durum wheat varieties (RGT Aventadur and Farah) and a lentil one (Altamura Lentil) under semi-controlled conditions. The isolated strains were classified using 16S rRNA gene sequencing. Results showed that they belonged to Pseudomonaceae, Rhizobiaceae, Bacillaceae and Micrococcaceae families. They exhibited typical features of PGPB, such as inorganic phosphate solubilization, production of indole acetic acid, ammonia, and biofilm formation. Bacterial inoculation of wheat plants led to the identification of potentially interesting strains that positively affected biometric parameters (i.e., shoot height, tiller number and spike weight) in a genotype-dependent way. The contrasting effect of some bacterial strains on the two wheat genotypes supports the necessity to accurately formulate synthetic microbial consortia characterized by long-term PGP traits, taking into account that the application under field conditions might also be influenced by native soil microbiota.

This review provides a comprehensive understanding about the mechanisms and technologies for the enhanced remediation of persistent organic pollutants (POPs)-contaminated soils by organic and biochar amendments. This article discusses the practical implications in relation to degradation, mobility, and bioavailability of POPs in soils. The application of organic (and carbonaceous) amendment lead to changes in soil’s pH, OM, and soluble organic carbon levels which might shift POPs from solid to aqueous phases, increasing their availability for microbial breakdown. Biochar can be useful as an electron donor, acceptor, or shuttle for microorganisms that degrade POPs (via different biological or chemical reactions) apart from its high surface area and excellent sorption properties (π–π interactions). Large amounts of organic such as composted manure, biosolids, municipal solid waste, and biochar amendments are utilized as a soil conditioner to enhance soil health and crop productivity as well as a source of carbon and nutrients, which can also impact the interactions of POPs in soil.

In this paper, a viability study is conducted for a bioremediation intervention in a cultivated area contaminated by a pipeline oil spill. In this context, green technologies such as bioremediation and phytoremediation could represent an optimal solution for reducing pollution without deteriorating soil quality. The phytoremediation test was conducted at the microcosm scale using three plant species (Zea mays, Lupinus albus and Medicago sativa) and at the mesocosm scale (Zea mays), also evaluating the application of plant growth-promoting bacteria (PGPB). The results showed that the selected plants, being able to grow satisfactorily, are able to lessen the presence of hydrocarbons in the soil. An increase of 15–18% in the degradation of the C > 12 fractions in vegetated soils was observed, confirming the effect of plants on the biodegradation of hydrocarbons in the soil. Moreover, a further improvement was recorded after adding PGPB, resulting in fresh biomass production being up to 50% higher than the controls and the degradation of the C > 12 fraction increasing by up to an additional 10%. Particular attention was also paid to pyrene, considered an indicator of PAH contamination. At the end of the experimentation in vegetated soils, pyrene removal reached values above 50%. By favoring plant growth, the addition of PGPB resulted in a further up to 20% reduction in the content of the contaminant in the soil. The primary role of the plants in soil contaminated by petroleum derivatives was to accelerate the degradation of contaminants through the stimulation of microbial activity. Therefore, the cooperation between plants and microorganisms can be concretely used as a nature-based solution in a sustainable and economical way.

Oil -produced waters are the most abundant wastewater stream in oil exploration and production, and their treatment is one of the most expensive processes in the petroleum industry. Since one of the peculiar characteristics of oil -produced waters is the presence of high salinity, developing an effective phytoremediation system for this type of wastewater first requires the selection of salt -tolerant plants. In this contribution, Halocnemum strobilaceum (Pallas) M. Bieb. and Suaeda fruticosa (L.) Forsk. were tested in experiments with mesocosms trials at different saline concentrations and hydrocarbons to study the plants' tolerance and the hydrocarbon degradation capacity. The experimental campaign showed species -specific results: H. strobilaceum showed better tolerance to salt and hydrocarbons, and Suaeda showed better performance as hydrocarbon degradation. The metagenomic analysis carried out on the roots of the plants at the end of the test highlighted significant speciation of the microbial communities, especially evident at the family level. The differences were detected when comparing the treatments and the two plant species. The Pseudomonadaceae family was generally predominant in mesocosms with Suaeda, whereas the Halomonadaceae family was dominant in those with H. strobilaceum. In parallel, some strains showing good potential for promoting plant growth were isolated. In conclusion, the experimentation allowed to identify the operating conditions for exploiting the technology as a sustainable alternative to consolidated technologies.

Water and soil salinity continuously rises due to climate change and irrigation with reused waters. Guayule (Parthenium argentatum A. Gray) is a desert perennial shrub native to northern Mexico and the southwestern United States; it is known worldwide for rubber production and is suitable for cultivation in arid and semiarid regions, such as the Mediterranean. In the present study, we investigated the effects of high and increasing concentrations of sodium chloride (NaCl) on the growth and the morphophysiological and biochemical characteristics of guayule to evaluate its tolerance to salt stress and suitability in phytomanagement and, eventually, the phytodesalinisation of salt-affected areas. Guayule originates from desert areas, but has not been found in salt-affected soils; thus, here, we tested the potential tolerance to salinity of this species, identifying the toxicity threshold and its possible sodium (Na) accumulation capacity. In a hydroponic floating root system, guayule seedlings were subjected to salinity-tolerance tests using increasing NaCl concentrations (from 2.5 to 40 g L−1 and from 43 to 684 mM). The first impairments in leaf morphophysiological traits appeared after adding 15 g L−1 (257 mM) NaCl, but the plants survived up to the hypersaline conditions of 35–40 g L−1 NaCl (about 600 mM). The distribution of major cell cations modulated the high Na content in the leaves, stems and roots; Na bioconcentration and translocation factors were close to one and greater than one, respectively. This is the first study on the morphophysiological and (bio)chemical response of guayule to different high and increasing levels of NaCl, showing the parameters and indices useful for identifying its salt tolerance threshold, adaptative mechanisms and reclamation potential in high-saline environments.

The effect of aging on cadmium (Cd) bioavailability and bioaccessibility was investigated in naturally aged field soil within a contaminated site. The results, which are based on a comparison of investigations carried out in 2018 and 2022 on the same soil samples, provide a realistic evaluation of the variation in Cd chemical forms due to long-term aging. The data obtained show a significant reduction (from approximately 30% to 60%) in the mobile and bioavailable forms of cadmium, while the total quantity in soil did not change significantly. The effect of aging on the bioavailable fractions is also reflected in the reduction in the amount of the metal absorbed by plants. On the one hand, this indicates a reduction in the potential contamination of the food chain, while on the other, it highlights the limitations of the use of phytoextraction as a clean-up technology in this specific site. In the case under study, it should also be noted that there was no decrease in cadmium bioaccessibility over time, which remained very high even after four years of cadmium aging in the soil, which was about 60% of the total content in the most contaminated soil samples. This highlights the potential health risks related to the incidental ingestion of Cd-contaminated soil, which could become the main exposure route in the case of the final use of the site as a park or public green area.

IntroductionFood crops are increasingly susceptible to the challenging impacts of climate change, encompassing both abiotic and biotic stresses, that cause yield losses. Root-associated microorganisms, including plant growth-promoting bacteria (PGPB), can improve plant growth as well as plant tolerance to environmental stresses. The aims of this work were to characterize bacteria isolated from soil and roots of tomato plants grown in open field.MethodsBiochemical and molecular analyses were used to evaluate the PGP potential of the considered strains on tomato plants in controlled conditions, also assessing their effects under a water deficit condition. The isolated strains were classified by 16S gene sequencing and exhibited typical features of PGPB, such as the release of siderophores, the production of proteases, and phosphorous solubilization. Inoculating tomato plants with eleven selected strains led to the identification of potentially interesting strains that increased shoot height and dry weight. Three strains were then selected for the experiment under water deficit in controlled conditions. The tomato plants were monitored from biometric and physiological point of view, and the effect of inoculation at molecular level was verified with a targeted RT-qPCR based approach on genes that play a role under water deficit condition.ResultsResults revealed the PGP potential of different bacterial isolates in tomato plants, both in well-watered and stressed conditions. The used integrated approach allowed to obtain a broader picture of the plant status, from biometric, eco-physiological and molecular point of view. Gene expression analysis showed a different regulation of genes involved in pathways related to abscisic acid, osmoprotectant compounds and heat shock proteins, depending on the treatments. DiscussionOverall, results showed significant changes in tomato plants due to the bacterial inoculation, also under water deficit, that hold promise for future field applications of these bacterial strains, suggesting that a synergistic and complementary interaction between diverse PGPB is an important point to be considered for their exploitation.

Hypersaline environments occur naturally worldwide in arid and semiarid regions or in artificial areas where the discharge of highly saline wastewaters, such as produced water (PW) from oil and gas industrial setups, has concentrated salt (NaCl). Halophytes can tolerate high NaCl concentrations by adopting ion extrusion and inclusion mechanisms at cell, tissue, and organ levels; however, there is still much that is not clear in the response of these plants to salinity and completely unknown issues in hypersaline conditions. Mechanisms of tolerance to saline and hypersaline conditions of four different halophytes (Suaeda fruticosa (L.) Forssk, Halocnemum strobilaceum (Pall.) M. Bieb., Juncus maritimus Lam. and Phragmites australis (Cav.) Trin. ex Steudel) were assessed by analysing growth, chlorophyll fluorescence and photosynthetic pigment parameters, nutrients, and sodium (Na) uptake and distribution in different organs. Plants were exposed to high saline (257 mM or 15 g L−1 NaCl) and extremely high or hypersaline (514, 856, and 1712 mM or 30, 50, and 100 g L−1 NaCl) salt concentrations in a hydroponic floating culture system for 28 days. The two dicotyledonous S. fruticosa and H. strobilaceum resulted in greater tolerance to hypersaline concentrations than the two monocotyledonous species J. maritimus and P. australis. Plant biomass and major cation (K, Ca, and Mg) distributions among above- and below-ground organs evidenced the osmoprotectant roles of K in the leaves of S. fruticosa, and of Ca and Mg in the leaves and stem of H. strobilaceum. In J. maritimus and P. australis the rhizome modulated the reduced uptake and translocation of nutrients and Na to shoot with increasing salinity levels. S. fruticosa and H. strobilaceum absorbed and accumulated elevated Na amounts in the aerial parts at all the NaCl doses tested, with high bioaccumulation (from 0.5 to 8.3) and translocation (1.7–16.2) factors. In the two monocotyledons, Na increased in the root and rhizome with the increasing concentration of external NaCl, dramatically reducing the growth in J. maritimus at both 50 and 100 g L−1 NaCl and compromising the survival of P. australis at 30 g L−1 NaCl and over after two weeks of treatment.

Legumes maintain soil fertility thanks to their associated microbiota but are threatened by climate change that causes soil microbial community structural and functional modifications. The core microbiome associated with different chickpea and lentil genotypes was described after an unexpected climatic event. Results showed that chickpea and lentil bulk soil microbiomes varied significantly between two sampling time points, the first immediately after the rainfall and the second 2 weeks later. Rhizobia were associated with the soil of the more productive chickpea genotypes in terms of flower and fruit number. The root-associated bacteria and fungi were surveyed in lentil genotypes, considering that several parcels showed disease symptoms. The metabarcoding analysis revealed that reads related to fungal pathogens were significantly associated with one lentil genotype. A lentil core prokaryotic community common to all genotypes was identified as well as a genotype-specific one. A higher number of specific bacterial taxa and an enhanced tolerance to fungal diseases characterized a lentil landrace compared to the commercial varieties. This outcome supported the hypothesis that locally adapted landraces might have a high recruiting efficiency of beneficial soil microbes.

In the context of the climate change scenario in the Mediterranean, natural root-microorganism associations have an impact on the resilience and productivity of crops, and the exploitation of these interactions represents innovative, cost-effective and sustainable crop adaptation strategies. An open field experiment with two commercial Italian tomato cultivars was performed. The soil bacterial communities associated with the two commercial Italian tomato genotypes were characterized alongside their physiological and molecular responses under wellwatered and moderate water deficit (100% and 75% of crop evapotranspiration) treatments. The two genotypes showed contrasting responses to water deficit, primarily through diverse rhizosphere microbiota recruitment under the two irrigation treatments. Highlights - Two tomato genotypes were studied under water deficit in a pilot field trial. - The two genotypes responded differently to water stress from eco-physiological and transcriptomic points of view. - The two genotypes recruited diverse root-associated microbiota, particularly under water deficit.

Arsenic (As) is one of the most common inorganic pollutants; unfortunately, it is also one of the most toxic and is therefore a cause of great concern for the health risks that could result from it. Removing arsenic from the soil using phytoremediation approaches is an effective strategy, and several studies demonstrate the ability of Cannabis sativa (TSN 19109, hemp) to tolerate this harmful contaminant. The aim of this work was to identify the best experimental conditions for a phytoremediation plan to be applied in a disused area located in Sicily (Italy) and contaminated by As, comparing Cannabis sativa with Brassica juncea (TSN 23059) and Zea mays (TSN 42269, corn). To assist the process, several chelating agents were tested to improve arsenic mobility, and two different sets of arsenic-tolerant bacteria were isolated from the rhizospheric soil of indigenous herbaceous species and used to promote plant growth, leading to a significant improvement in terms of biomass produced and phytoextraction. After the combined treatment, the arsenic content in the aerial part of the plants increased by more than two orders of magnitude (e.g., from 0.05 to 6.57 mg kg−1, from 0.04 to 6.69 mg kg−1, and from 0.03 to 5.57 mg kg−1 for brassica, corn, and hemp, respectively), confirming the marked increase in the total absorption of As by plants.

Spills of petroleum products resulting from illegal pipeline extraction also affect agricultural areas. These areas must be subject to remediation interventions to bring the concentrations of contaminants below the alarm levels and avoid further damage to the environment and living beings. In these cases, green technologies such as bioremediation and phytoremediation are an excellent approach to reduce impacts on agriculture. This contribution evaluates the effectiveness of combining some green techniques in managing soil contaminated by oil spills. A feasibility test of phytoremediation at a microcosm scale with three plant species (corn, lupine and alfalfa) was conducted, combining the approach with plant growth-promoting rhizobacteria (PGPR). Particular attention was given to the reclamation from polycyclic aromatic hydrocarbons (PAHs). At the end of the experiments, biomass production and PAHs concentration in the soil and plants (roots and aerial parts) were determined. The remediation strategy was aimed at two concurrent objectives: the need to remove the maximum amount of contaminants from the soils affected by oil spills and the restoration of the agricultural activity to be carried out in absolute safety. The results show a decrease in the concentration of hydrocarbons in the soil favored by the presence of tested plants, which manage to grow satisfactorily on the soil under examination, albeit with an inevitable decrease in yield compared to uncontaminated soil. Looking at the concentration of pyrene, which is usually considered as indicator of PAHs contamination, the removal reaches values higher than 50 % in vegetated soils. The addition of the selected PGPR counteract the negative effect of contamination, favoring the growth of plants and allowing the production of fresh biomass comparable to that obtained on the uncontaminated control soil. This results in a further reduction of the contaminant in question up to an additional 20 %. Therefore, the presence of organic contaminants can be concretely reduced in a sustainable and cost-effective way by the joint action of plants and microorganisms that promote the processes of rizodegradation.

Many agricultural areas are contaminated by heavy metals to such a level that the growth of plants is drastically reduced. Based on the site’s specific characteristics, feasibility studies were carried out to choose the most effective technologies. Feasibility tests showed that soil washing and phytoremediation technologies could be used at the agricultural site under study. The efficiency of the technologies is highly dependent on soil characteristics, which determine the chemical form of the metals. The results indicate that water-based soil washing can be successfully used with the possibility of reaching the remediation objectives quickly. However, the technology in the first step essentially breaks down the soil. Moreover, phytoremediation cannot be used directly to overcome the toxicity derived from the very high bioavailability of the heavy metals. Still, there is the need to use “assisted” phytoremediation by adding compost that reduces metal bioavailability, allowing phytoextraction. In this case, a longer time is needed to reach the remediation target. The results provide a preliminary scenario for decision-makers and stakeholders to assess possible technologies applicable and a possible scheme to be applied in similar cases of polluted agricultural areas.

The research studied the effects of petroleum hydrocarbons (PHs) on Salicornia perennans Willd. at different saline concentrations. The study investigated 1) in vitro germination and 2) plants growth in hydroponics conditions. PHs, together with salinity, strongly affected the germination. Under saline conditions, PHs generally stimulated germination in terms of time and final rate. Plant growth and the photosynthetic performance were significantly affected at 0 g/l of salt and with high PHs addition. Hence, the saline conditions seem to be necessary to enable the resistance to the PHs stress.