Allochthonous Strains Research Articles

A local or a stranger? Comparison of autochthonous vs. allochthonous microalgae potential for bioremediation of coal mine drainage water

Coal mining endangers the environment by contaminating of soil, surface, and ground water with coal mine drainage water (CMW) polluted by heavy metals. Microalgal cultures, hyper-accumulators of heavy metals, represent a promising solution for CMW biotreatment. A bottleneck of this approach is the availability of microalgal strains that combine a large capacity for heavy metal biocapture with a high resilience to their toxic effects. Biotopes contaminated with heavy metals are frequently inhabited by microalgae evolved to be resilient to heavy metal toxicity. Therefore, the autochthonous (locally isolated) microalgal strains are a priori considered to be superior for biotreatment of heavy metal-polluted waste streams. Still, strains from biocollections combine a high pollutant resilience with other biotechnologically important traits such as high productivity, high CO2 sequestration rate etc. Moreover, the strains available “off-the-shelf” would enable rapid development of bioprocesses. Here, we compared the efficiency of CMW biotreatment with autochthonous (isolated from the coal mine drainage sump) and allochthonous microalgae (from a geographically distant phosphate-polluted site). Both autochthonous strains and allochthonous strains turned to be interchangeable under our experimental conditions. Still, the autochthonous strains showed a higher capacity for sequestration of iron, zinc, and manganese, the specific pollutants of the studied CMW. It can be important when the duration of unattended exploitation of the CMW treatment facility is a priority or spikes of the heavy metal concentration in CMW are expected. Therefore, the “off-the-shelf” strains can be a plausible solution for rapid development of CMW treatment technologies from scratch (although screening for acute toxicity of CMW is imperative). On the other hand, locally isolated strains can offer distinct advantages and should be always considered if sufficient time and other resources are available for the development of microalgae-based process for CMW treatment.

Fungal Arsenic Tolerance and Bioaccumulation: Local Strains from Polluted Water vs. Allochthonous Strains

The paper deals with the possible use of fungi to decontaminate polluted waters. Specifically, the focus is the selection of the most promising fungal strain capable of bioaccumulating arsenic, which is a globally widespread environmental contaminant. To this aim, allochthonous fungal strains from the ColD UNIGE JRU MIRRI strains collection were selected. Their capability to survive and accumulate this kind of pollutant was evaluated and compared with that of an autochthonous fungi set directly isolated from the arsenic polluted water. A preliminary screening at various concentrations of arsenic (0, 200, 400, 800, 1600 μg L−1) revealed that the best performing strains were Aspergillus niger and Penicillium expansum among the autochthonous strains and Aspergillus niger and Penicillium expansum among the allochthonous strains. Moreover, all the strains were subjected to bioaccumulation tests at a 1600 μg L−1 concentration. Local and allochthonous fungal strains showed different behaviors: the allochthonous strains grew rapidly and in a sustained way but without expressing any bioaccumulation activity. On the contrary, the indigenous fungi, despite a moderate growth, showed a good bioaccumulation capacity (in particular, Aspergillus niger). The results highlight the importance of employing native strains isolated from contaminated matrices to make a mycoremediation protocol more efficient.

Study of dairy heterofermentative lactic acid bacilli for cereal-based matrices

Forty obligate heterofermentative lactic acid bacilli (HB) isolated from dairy environment as non-starter lactic acid bacteria (NSLAB) were studied regarding their potential as novel starter cultures for fermented foods. Preliminary genotipic and phenotypic tests allowed the selection of 16 strains, identified as Limosilactobacillus fermentum (12 strains), Levilactobacillus brevis (2), Lentilactobacillus buchneri (1) and Weissella confusa (1). They were initially studied at the technological level, focusing on stress factors (low temperature, heat, salt and acidic media), growth in milk, viability after freezing and thawing and growth in cereal-based matrices. Based on this, six strains were chosen for further studies: L. brevis (LB61 and LB66), L. buchneri (LBu39), L. fermentum (LF22 and LF68) and W. confusa (W20). The selected strains grew well in wheat and gluten-free (GF) doughs, produced exopolysaccharides, acetic and lactic acid in a ratio (<1:5) that allowed the inhibition of undesirable organisms without causing off-flavours, and had good salt resistance. Among them, Weissella confusa W20 was used as starter culture for sourdough fermentation to manufacture gluten-free breads, showing noticeable improvements at the organoleptic level in comparison to GF breads fermented only with yeast. This work remarks the importance of studying the potential of wild strains to find alternative matrices beyond those from where they were isolated. With this regard, our investigation allowed the selection of six dairy strains with potential as starter cultures for bread making, which reaffirms that allochthonous strains can be suitable for sourdough preparation.

Selection of Autochthonous LAB Strains of Unripe Green Tomato towards the Production of Highly Nutritious Lacto-Fermented Ingredients.

Lactic fermentation of unripe green tomatoes as a tool to produce food ingredients is a viable alternative for adding value to industrial tomatoes unsuitable for processing and left in large quantities in the fields. Fermentation using starter cultures isolated from the fruit (plant-matrix adapted) can have advantages over allochthonous strains in obtaining fermented products with sensory acceptability and potentially probiotic characteristics. This paper details the characterisation of the unripe green tomato lactic microbiota to screen LAB strains for use as starter cultures in fermentation processes, along with LAB strains available from INIAV’s collection. Morphological, biochemical (API system), and genomic (16S rDNA gene sequencing) identification showed that the dominant LAB genera in unripe green tomato are Lactiplantibacillus, Leuconostoc, and Weissella. Among nine tested strains, autochthonous Lactiplantibacillus plantarum and allochthonous Weissella paramesenteroides showed tolerance to added solanine (200 ppm) and the best in vitro probiotic potential. The results indicate that the two LAB strains are promising candidates for manufacturing probiotic fermented foods from unripe green tomatoes.

Surveillance and habitat diversity affect European brown hare (Lepus europaeus) density in protected breeding areas

The European brown hare (Lepus europaeus) is an important game species throughout Europe. In Italy, for preventing the introduction of allochthonous strains, the management of brown hare populations has focused on the establishment of small protected areas (ZRCs), appositely managed for disposing of wild-born hares for restocking hunting territories. We investigated the effects of both land cover and surveillance on hare density and habitat preferences in 20 ZRCs, monitored twice per year (pre- and post-breeding periods) between 1997 and 2017. Density, as assessed by spotlight counts, ranged between 2.8 and 47.0 ind/km2 in spring and 5.0 and 68.4 ind/km2 in autumn. Surveillance, percent length of protected boundaries, year of institution and habitat diversity, as assessed by Shannon’s Index, were the main factors affecting hare density. During their foraging activity, hares selected ryegrass, hayfields and lucerne, while avoided maize stubble and ploughed fields and were never recorded in poplar plantations or next to human settlements. While the effects of habitat heterogeneity on hare density have been widely studied, we suggest that the involvement of local stakeholders may be of paramount importance for ensuring effective conservation measures.

Formulation of a Highly Effective Inoculant for Common Bean Based on an Autochthonous Elite Strain of Rhizobium leguminosarum bv. phaseoli, and Genomic-Based Insights Into Its Agronomic Performance.

Common bean is a poor symbiotic N-fixer, with a low response to inoculation owing to its promiscuous nodulation with competitive but inefficient resident rhizobia. Consequently, farmers prefer to fertilize them rather than rely on their capacity for Biological Nitrogen Fixation (BNF). However, when rhizobial inoculants are based on autochthonous strains, they often have superior BNF performance in the field due to their genetic adaptations to the local environment. Nevertheless, there is scant information at the genomic level explaining their superiority or on how their genomes may influence the inoculant performance. This information is especially important in technologically advanced agri-systems like Europe, where environmental concerns and increasingly stringent fertilizer regulations are encouraging a return to the use of rhizobial inoculants, but based upon strains that have been thoroughly characterized in terms of their symbiotic performance and their genetics. The aim of this study was to design an inoculant formulation based on a superior autochthonous strain, Rhizobium leguminosarum bv. phaseoli LCS0306, to assess its performance in the field, and to determine the genomic features contributing to the high effectiveness of its symbiosis with common bean. Plants inoculated with the autochthonous strain LCS0306 fixed significantly more nitrogen than those with the allochthonous strains R. phaseoli ATCC 14482T and R. etli CFN42T, and had grain yield similar to the nitrogen-fertilized controls. Inoculation with LCS0306 was particularly efficacious when formulated with a carrier based upon a mixture of perlite and biochar. Whole genome comparisons revealed no differences in the classical symbiotic genes of strain LCS0306 within the symbiovar phaseoli. However, its symbiotic superior performance might be due to its genomic versatility, as it harbors a large assortment of genes contributing to fitness and competitiveness. It is concluded that inoculation with elite rhizobia formulated with perlite-biochar carriers might constitute a step-change in the sustainable cultivation of common bean in Spanish soils.

Autochthonous vs allochthonous probiotic strains to Rhamdia quelen

The aim of this study was to obtain an autochthonous probiotic candidate strain from the silver catfish (Rhamdia quelen) intestinal tract, comparing its in vivo performance with an allochthonous probiotic isolated from another fish, Nile tilapia (Oreochromis niloticus), in a growth performance assay. The study was divided in two parts: in vitro and in vivo assay followed by challenge with A. hydrophila. In the in vitro assay, the species-specific isolated strain Lactococcus lactis presented characteristics such as: absence of hemolysis, antagonism to bacterial pathogens isolated from freshwater fish, and considerable speed of duplication. In the in vivo trial, both fish supplemented with autochthonous or allochthonous strains presented an increase the final concentration of lactic acid bacteria in the intestinal tract of the fish after 60 days of dietary supplementation reaching concentrations of 1 × 107 CFU g−1 and 4 × 107 UFC.g−1, respectively. In addition, the autochthonous strain increased the mean corpuscular hemoglobin (MCH) of the treated animals, but no significant differences were observed in the other hemato-immunological and zootechnical parameters between treatments. After challenge with Aeromonas hydrophila, only animals that received autochthonous probiotic supplementation showed an increase in the serum total immunoglobulin concentration, but not enough to observe a significant difference in the survival rate between the treatments. Dietary supplementation of the probiotic allochthonous strain did not demonstrate any effects superior to those of the isolated autochthonous strain. Although the autochthonous strain did not present significant improvements in the other parameters evaluated in this study, it was able to inhibit bacterial pathogens in vitro, to increase the final concentration of LAB's and the amount of immunoglobulin after experimental challenge, demonstrating probiotic potential. This study demonstrated for the first time the isolation and in vivo use of an autochthonous probiotic strain isolated from silver catfish, as well as its comparative evaluation with the performance of allochthonous probiotic.

Antibiotic disturbance affects aquatic microbial community composition and food web interactions but not community resilience.

Notwithstanding the fundamental role that environmental microbes play for ecosystem functioning, data on how microbes react to disturbances are still scarce, and most factors that confer stability to microbial communities are unknown. In this context, antibiotic discharge into the environment is considered a worldwide threat for ecosystems with potential risks to human health. We therefore tested resilience of microbial communities challenged by the presence of an antibiotic. In a continuous culture experiment, we compared the abundance, composition and diversity of microbial communities undisturbed or disturbed by the constant addiction of tetracycline in low (10µg/L) or intermediate (100µg/L) concentration (press disturbance). Further, the bacterial communities in the three treatments had to face the sudden pulse disturbance of adding an allochthonous bacterium (Escherichia coli). Tetracycline, even at low concentrations, affected microbial communities by changing their phylogenetic composition and causing cell aggregation. This, however, did not coincide with a reduced microbial diversity, but was mainly caused by a shift in dominance of specific bacterial families. Moreover, the less disturbed community (10µg/L tetracycline) was sometimes more similar to the control and sometimes more similar to heavily disturbed community (100µg/L tetracycline). All in all, we could not see a pattern where the communities disturbed with antibiotics were less resilient to a second disturbance introducing E. coli, but they seemed to be able to buffer the input of the allochthonous strain in a similar manner as the control.

Bioremediation of Landfill Leachate with Fungi: Autochthonous vs. Allochthonous Strains.

Autochthonous fungi from contaminated wastewater are potential successful agents bioremediation thanks to their adaptation to pollutant toxicity and to competition with other microorganisms present in wastewater treatment plant. Biological treatment by means of selected fungal strains could be a potential tool to integrate the leachate depuration process, thanks to their fungal extracellular enzymes with non-selective catalytical activity. In the present work, the treatability of two real samples (a crude landfill leachate and the effluent coming from a traditional wastewater treatment plant) was investigated in decolorization experiments with fungal biomasses. Five autochthonous fungi, Penicillium brevicompactum MUT 793, Pseudallescheria boydii MUT 721, P. boydii MUT 1269, Phanerochaete sanguinea MUT 1284, and Flammulina velutipes MUT 1275, were selected in a previous miniaturized decolorization screening. Their effectiveness in terms of decolorization, enzymatic activity (laccases and peroxidases), biomass growth and ecotoxicity removal was compared with that of five allochthonous fungal strains, Pleurotus ostreatus MUT 2976, Porostereum spadiceum MUT 1585, Trametes pubescens MUT 2400, Bjerkandera adusta MUT 3060 and B. adusta MUT 2295, selected for their well known capability to degrade recalcitrant pollutants. Moreover, the effect of biomass immobilization on polyurethane foam (PUF) cube was assessed. The best decolorization (60%) was achieved by P. spadiceum MUT 1585, P. boydii MUT 721 and MUT 1269. In the first case, the DP was achieved gradually, suggesting a biodegradation process with the involvement of peroxidases. On the contrary, the two autochthonous fungi seem to bioremediate the effluent mainly by biosorption, with the abatement of the toxicity (up to 100%). The biomass immobilization enhanced enzymatic activity, but not the DP. Moreover, it limited the biomass growth for the fast growing fungi, MUT 721 and MUT 1269. In conclusion, robust and versatile strains coming from well-characterized collections of microorganisms can obtain excellent results comparing and even exceeding the bioremediation yields of strains already adapted to pollutants.

Inter-Population Differences and Seasonal Dynamic of the Bacterial Gut Community in the Endangered Land SnailHelix pomatia(Gastropoda: Helicidae)

ABSTRACT Among the multifaceted environmental factors, the bacterial community ingested with soil and food might play an important role in physiological processes of terrestrial gastropods, with consequences on population dynamics and species distribution patterns. Therefore, we investigated the bacterial gut community structure and seasonal dynamic in three populations of the protected endangered land snail Helix pomatia. The PCR-DGGE fingerprinting analysis followed by Nonmetric Multidimensional Scaling (NMDS) showed that Gamma-and Alphaproteobacteria were common to all populations, while Mollicutes and Betaproteobacteria were population specific. Allochthonous strains might be transiently abundant in the gut of foraging snails with respect to habitat conditions. Autochthonous strains were permanently present in the gut, even after expulsion of the gut content at hibernation beginning. Some of these permanent strains are known to have ice-nucleating activity, which is consistent with the limited cold ha...

Assessment of the potential role of Streptomyces strains in the revegetation of semiarid sites: the relative incidence of strain origin and plantation site on plant performance and soil quality indicators

We performed a field assay to assess the efficacy of strains of actinobacteria belonging to the Streptomyces genus, isolated from two Mediterranean semiarid sites (Rellano and Calblanque) with different soil characteristics, with regard to the establishment of Rhamnus lycioides L. seedlings in both locations, as well as their effect on soil chemical and microbiological properties 1 year after planting. At the Calblanque site, the inoculation with native strains was more effective than that with allochthonous strains, with respect to increasing shoot dry weight (about 48 and 28 %, respectively, compared to control plants), primarily due to improvements in NPK uptake and plant drought tolerance. However, at Rellano, the efficacy of plant growth promotion was not influenced by the strain origin. The highest increases in the urease, protease, and dehydrogenase activities and in microbial biomass C in response to inoculation with actinobacteria occurred at the Rellano site (about 200, 28, 29, and 30 %, respectively, compared to the respective controls), regardless of the origin of the strain assayed. Strain origin and the biological fertility of the plantation site should be considered in the selection of strains of actinobacteria for use in the revegetation with shrub species in semiarid environments.

Contribution of arbuscular mycorrhizal fungi and/or bacteria to enhancing plant drought tolerance under natural soil conditions: Effectiveness of autochthonous or allochthonous strains

Autochthonous microorganisms [a consortium of arbuscular-mycorrhizal (AM) fungi and Bacillus thuringiensis (Bt)] were assayed and compared to Rhizophagus intraradices (Ri), Bacillus megaterium (Bm) or Pseudomonas putida (Psp) and non-inoculation on Trifolium repens in a natural arid soil under drought conditions. The autochthonous bacteria Bt and the allochthonous bacteria Psp increased nutrients and the relative water content and decreased stomatal conductance, electrolyte leakage, proline and APX activity, indicating their abilities to alleviate the drought stress. Mycorrhizal inoculation significantly enhanced plant growth, nutrient uptake and the relative water content, particularly when associated with specific bacteria minimizing drought stress-imposed effects. Specific combinations of autochthonous or allochthonous inoculants also contributed to plant drought tolerance by changing proline and antioxidative activities. However, non-inoculated plants had low relative water and nutrients contents, shoot proline accumulation and glutathione reductase activity, but the highest superoxide dismutase activity, stomatal conductance and electrolyte leakage. Microbial activities irrespective of the microbial origin seem to be coordinately functioning in the plant as an adaptive response to modulated water stress tolerance and minimizing the stress damage. The autochthonous AM fungi with Bt or Psp and those allochthonous Ri with Bm or Psp inoculants increased water stress alleviation. The autochthonous Bt showed the greatest ability to survive under high osmotic stress compared to the allochthonous strains, but when single inoculated or associated with Ri or AM fungi were similarly efficient in terms of physiological and nutritional status and in increasing plant drought tolerance, attenuating and compensating for the detrimental effect of water limitation.

Comparison of the Colonization Ability of Autochthonous and Allochthonous Strains of Lactobacilli in the Human Gastrointestinal Tract

Bacteria of the genus Lactobacillus are widely used as oral probiotics due to their putative health benefits. In this study, we compared the colonization ability of two Lactobacillus strains that were identified as autochthonous to the human gastrointestinal tract (Lactobacillus reuteri ATCC PTA 6475 (MM4-1a) and Lactobacillus mucosae FSL-04) with that of an allochthonous strain (Lactobacillus acidophilus DDS-1). Colonization ability was tested in a single-blinded, cross-over study, with twelve human subjects. The test strains were quantified in fecal samples by two independent methods, selective plating and molecular typing and quantitative real time PCR. The study revealed that the two autochthonous strains (L. reuteri ATCC PTA 6475 and L. mucosae FSL-04) reached higher population levels in fecal samples and were recovered more frequently from subjects compared to the allochthonous strain (L. acidophilus DDS-1). All three strains became undetectable 8 days after the end of consumption with one exception, showing that persistence of all three strains remains short term in most individuals. In conclusion, this study showed that autochthonous Lactobacillus strains can be established more efficiently, albeit temporarily, in the human gastrointestinal tract, suggesting that evolutionary and ecological characteristics could be valuable criteria for the selection of probiotic strains.

Effectiveness of a microbial formula, as a bioaugmentation agent, tailored for bioremediation of diesel oil and heavy metal co-contaminated soil

The activation of natural bioremediation potentials is the challenge that research is currently addressing for overcoming bottlenecks still affecting bioremediation applications. Bioaugmentation is one possible way to activate such natural potentials, provided that the biodiversity introduced to increase catabolically relevant capacity is identified also considering the ecological context. The present work deals with bioaugmentation aimed at the remediation of a soil co-contaminated (spiked) with both diesel oil (1%, v/w), and heavy metals (Pb and Zn), using intact soil core microcosms in different experimental conditions. We supposed that both heavy metal resistance and active metabolism towards organic pollutants are essential metabolic traits to trap the energetic flux, which drives the microbial community towards biodegradation under the given experimental conditions. Consequently, the bioaugmentation was performed by introducing a tailor made microbial formula composed of 12 allochthonous strains. They belong to a stable population previously isolated from a chronic polluted site and are both hydrocarbon degraders and heavy metal resistant and, also, compatible with the autochthonous microbial community. The active role of the microbial formula in pushing the entire community towards an effective bioremediation of diesel oil close to 75%, in the presence of bioavailable metals, has been proven through hydrocarbons analysis, metabolic and molecular profiling at community level (Biolog system, DGGE).

Bacteria able to control foot and root rot and to promote growth of cucumber in salinated soils

The aim of the present work was to test known bacterial plant growth-promoting strains for their ability to promote cucumber plant growth in salinated soil and to improve cucumber fruit yield by protecting these plants against soil-borne pathogens. Fifty-two plant-beneficial bacterial strains were evaluated for their ability to protect plants against cucumber foot and root rot after bacterization of the seeds and infestation of salinated soil with the isolated Fusarium solani pathogen. Based on the results of initial screenings, five efficient strains were selected, namely Serratia plymuthica RR-2-5-10, Stenotrophomonas rhizophila e-p10, Pseudomonas fluorescens SPB2145, Pseudomonas extremorientalis TSAU20, and P. fluorescens PCL1751. All five strains are salt tolerant since they grow well in a medium to which 3% NaCl was added. Infestation of the soil with F. solani resulted in an increase of the percentage of diseased plants from 17 to 54. Priming of seedlings with the five selected bacterial strains reduced this proportion to as low as 10%. In addition, in the absence of an added pathogen, all five strains showed a significant stimulatory effect on cucumber plant growth, increasing the dry weight of whole cucumber plants up to 62% in comparison to the non-bacterized control. The strains also increased cucumber fruit yield in greenhouse varying from 9% to 32%. We conclude that seed priming with the selected microbes is a very promising approach for improving horticulture in salinated soils. Moreover, allochthonous strains isolated from non-salinated soil, from a moderate or even cold climate, and from other plants than cucumber, functioned as well as autochthonous strains as cucumber-beneficial bacteria in salinated Uzbek soils. These results show that these plant-beneficial strains are robust and they strongly suggest they can also be used successfully in case the climate gets warmer and the soils will become more salinated. Finally, the mechanisms by which they may exert their plant-beneficial action are discussed.

Investigation of mineral water springs of Miercurea Ciuc (Csíkszereda) region (Romania) with cultivation-dependent microbiological methods

Water samples of ten mineral water springs at Miercurea Ciuc (Csíkszereda) region (Romania) were examined during 2005-2006 using cultivation-dependent microbiological methods. The results of standard hygienic bacteriological tests showed that the Hargita Spring had perfect and five other springs had microbiologically acceptable water quality (Zsögöd-, Nagy-borvíz-, Taploca-, Szentegyháza- and Lobogó springs). The water of Borsáros Spring was exceptionable (high germ count, presence of Enterococcus spp.).Both standard bacteriological and molecular microbiological methods indicated that the microbiological water quality of the Szeltersz-, Nádasszék- and Délo springs was not acceptable. Bad water quality resulted from inadequate spring catchment and hygiene (low yield, lack of runoff, negligent usage of the springs, horse manure around the spring).The 16S rRNA gene-based identification of strains isolated on standard meat-peptone medium resulted in the detection of typical aquatic organisms such as Shewanella baltica, Aeromonas spp., Pseudomonas veronii, Psychrobacter sp,. Acinetobacter spp. and allochthonous microbes, like Nocardia, Streptomyces, Bacillus, Microbacterium , and Arthrobacter strains indicating the impact of soil. Other allochthonous microbes, such as Staphylococcus spp., Micrococcus sp., Lactococcus sp., Clostridium butyricum, Yersinia spp., Aerococcus sp., may have originated from animal/human sources.

Inhibitory Effect of Aged Petroleum Hydrocarbons on the Survival of Inoculated Microorganism in a Crude-Oil-Contaminated Site

We studied the effects of aged total petroleum hydrocarbons (aged TPH) on the survival of allochthonous diesel-degrading Rhodococcus sp. strain YS-7 in both laboratory and field investigations. The aged TPH extracted from a crude oil-contaminated site were fractionized by thin-layer chromatography/flame ionization detection (TLC/FID). The three fractions identified were saturated aliphatic (SA), aromatic hydrocarbon (AH), and asphaltene-resin (AR). The ratio and composition of the separated fractions in the aged TPH were quite different from the crude-oil fractions. In the aged TPH, the SA and AH fractions were reduced and the AR fraction was dramatically increased compared to crude oil. The SA and AH fractions (2 mg/L each) of the aged TPH inhibited the growth of strain YS-7. Unexpectedly, the AR fraction had no effect on the survival of strain YS-7. However, crude oil (1,000 mg/L) did not inhibit the growth of strain YS-7. When strain YS-7 was inoculated into an aged crude oil-contaminated field and its presence was monitored by fluorescent in situ hybridization (FISH), we discovered that it had disappeared on 36 days after the inoculation. For the first time, this study has demonstrated that the SA and AH fractions in aged TPH are more toxic to an allochthonous diesel-degrading strain than the AR fraction.

Effect of autochthonous lactic acid bacteria starters on health-promoting and sensory properties of tomato juices

Strains of Lactobacillus plantarum, Weissella cibaria/ confusa, Lactobacillus brevis, Pediococcus pentosaceous, Lactobacillus sp. and Enterococcus faecium/ faecalis were identified from raw tomatoes by Biolog System, partial 16S rRNA gene sequence and subjected to typing by Random Amplified Polymorphic DNA-Polymerase Chain Reaction (RAPD-PCR) analysis. Ten autochthonous strains were singly used to ferment tomato juice (TJ) via a protocol which included fermentation at 25 °C for 17 h and further storage at 4 °C for 40 days. Unstarted TJ and TJ fermented with an allochthonous strain of L. plantarum were used as the controls. All autochthonous strains grew well in TJ reaching cell densities ca. 10,000 and 10 times higher than unstarted TJ and TJ fermented with the allochthonous strain. Viscosity of TJs fermented with autochthonous strains was generally the highest, especially when started with W. cibaria/ confusa which synthesized exo-polysaccharides. Overall, unstarted TJ and TJ fermented with the allochthonous strain showed marked decreases of ascorbic acid (ASC), glutathione (GSH) and total antioxidant activity (TTA) during storage. On the contrary, several TJs fermented with autochthonous strains, especially with L. plantarum POM1 and POM 35, maintained elevated values of ASC, GSH and TAA. The variation of color indexes mirrored the above behavior. TJs fermented with the above two autochthonous strains were compared to controls based on volatile components through Purge and Trap or Solid Phase Microextraction Gas Chromatography-Mass Spectrometry (PT or SPME-GC/MS) analysis. As shown by Principal Component Analysis a large number of volatiles belonging to various chemical classes markedly differentiated TJs fermented with autochthonous strains with respect to controls.

Drought Tolerance and Antioxidant Activities in Lavender Plants Colonized by Native Drought-tolerant or Drought-sensitive Glomus Species

This study compared the effectiveness of four arbuscular mycorrhizal (AM) fungal isolates (two autochthonous presumably drought-tolerant Glomus sp and two allochthonous presumably drought-sensitive strains) on a drought-adapted plant (Lavandula spica) growing under drought conditions. The autochthonous AM fungal strains produced a higher lavender biomass, specially root biomass, and a more efficient N and K absorption than with the inoculation of similar allochthonous strains under drought conditions. The autochthonous strains of Glomus intraradices and Glomus mosseae increased root growth by 35% and 100%, respectively, when compared to similar allochthonous strains. These effects were concomitant with an increase in water content and a decline in antioxidant compounds: 25% glutathione, 7% ascorbate and 15% H(2)O(2) by G. intraradices, and 108% glutathione, 26% ascorbate and 43% H(2)O(2) by G. mosseae. Glutathione and ascorbate have an important role in plant protection and metabolic function under water deficit; the low cell accumulation of these compounds in plants colonized by autochthonous AM fungal strains is an indication of high drought tolerance. Non-significant differences between antioxidant activities such as glutathione reductase (GR), catalase (CAT) and superoxide dismutase (SOD) in colonized plants were found. Thus, these results do not allow the generalization that GR, CAT and SOD were correlated with the symbiotic efficiency of these AM fungi on lavender drought tolerance. Plants colonized by allochthonous G. mosseae (the less efficient strain under drought conditions) had less N and K content than those colonized by similar autochthonous strain. These ions play a key role in osmoregulation. The AM symbiosis by autochthonous adapted strains also produced the highest intraradical and arbuscular development and extraradical mycelial having the greatest fungal SDH and ALP-ase activities in the root systems. Inoculation of autochthonous drought tolerant fungal strains is an important strategy that assured the greatest tolerance water stress contributing to the best lavender growth under drought.

The use of a multidisciplinary approach for the characterization of a diploid parthenogenetic Artemia population from Torre Colimena (Apulia, Italy)

A parthenogenetic Artemia population from Torre Colimena, southern Italy, originally reported in 1998, is characterized by a multidisciplinary approach including cyst and naupliar biometry, morphometry of adults, scanning electron microscopy (SEM) of brood pouch, cytogenetics and 16S rRNA PCR-RFLP analysis. We confirmed parthenogenetic status, inferred ploidy level and determined phenotypic and molecular relationships of this population through comparisons with other asexual Artemia strains as well as bisexual species found (A. salina) or introduced (A. franciscana) in the Mediterranean basin. Cyst and naupliar sizes for Torre Colimena are among the smallest recorded for asexual Artemia while the opposite is true for chorion thickness. Discriminant analysis of adult body measurements shows increased differentiation (89.5% for the first four out of the taselve functions produced) from tetraploid parthenogenetic strains and bisexual species (A. salina and A. franciscana). Scanning electron micrographs of brood pouch reveal the characteristic morphology of asexual strains, while chromosome observations of instar-I nauplii unequivocally establish diploid>. Restriction patterns give evidence that the Torre Colimena population shares an identical set of mitochondrial DNA (mtDNA) polymorphisms with a diploid Spanish parthenogenetic strain and it is well differentiated from other tetraploid as well as bisexual auto- and allochthonous strains (A. salina and A. franciscana) from the Mediterranean. The present study may serve as a reference methodological framework for multidisciplinary characterization and biodizjersiy assessments in the genus Artemia.