Freshwater bacterial diversity, functions and stability.

Biodiversity is declining worldwide with detrimental effects on ecosystems functions and services that it sustains. The relationship between biodiversity and freshwater purification remains unclear. Freshwater purification is of paramount importance for humankind as eighty percent of the worlds population is exposed to high levels of threat in terms of water security. Bacteria are the most diverse and abundant organisms on Earth and they play, directly or indirectly, a key role in the majority of ecosystem services including water purification. The current work aimed, in freshwater systems, to unravel the relationships between microbial diversity and: (a) biodegradation of toxic compounds (i.e. specialised function); (b) respiration (i.e. broad function) and; (c) stability of broad functioning. Firstly, preliminary experiments were carried out to establish freshwater sample size to representatively evaluate bacterial communities diversity and also suitable natural and man-made toxic compounds for freshwater incubation experiments. Then, the microbial communities ability to degrade microcystin-LR was explored in the context of previous exposures and nutrient availability. Finally, we focused on the relationships between diversity and functioning. A decrease in microbial diversity caused a decrease in both broad and specialised ecosystem functions tested. Stability of broad functioning was also negatively affected by a decrease in microbial diversity. Both lakes (Scotland) and rivers (Australia) microcosms experiments resulted in comparable findings suggesting consistent relationships across different freshwater systems. These results highlight that, similarly to macro-organisms (plant and animals), declining diversity of the microbial communities has direct consequences for important ecosystem functioning and services and therefore, microbial diversity should be explicitly considered in all biodiversity conservation debates

Strategies for the re-naturalization of reforestation: the case study of the Sicilian clay hills

Over the last decades many areas have been reforested along Europe, with great proportion been made with exotic species. Very often these reforestations do not evolve in more diverse configurations, where some kind of management can be necessary to try to enhance this evolution. The hole is a silvicultural technique consisting in open small gaps to create favourable conditions for the establishment of other species changing the former structure, microclimate and competitive conditions mirroring this natural processes that occurs in structured and mature forests. The best size of the hole seems to be around 500 m\ub2, as small holes may not change significantly the conditions and larger holes seems to favour degradation processes like soil erosion and loss of organic layers. The afforestaion of the Santa Ninfa Natural Reserve (Trapani Province, W-Sicily) were made using essentially Pinus spp. and Eucalyptus camaldulensis. Particularly, this last specie occur in high density monospecific forest structure covering 19 ha (8% of the reserve), where practically no kind of management has been made until now and very few natural regenerations is observed. The aim of the study was to verify the effectiveness of the restoration actions combining the hole technique and planting native species with different management levels

Use of Kluyveromyces marxianus to Increase Free Monoterpenes and Aliphatic Esters in White Wines

An increasing interest in novel wine productions is focused on non-Saccharomyces yeasts due to their potential in improving sensory profiles. Although Kluyveromyces marxianus has been originally isolated from grapes and its enzymatic activities are used in oenology, rarely it has been used as co-starter. The K. marxianus Km L2009 strain has been characterized here and selected as a co-starter both at laboratory- and winery-scale fermentation. The Km L2009 strain showed growth of up to 40 (mg/L) of sulfites and 6% (v/v) of ethanol. Gas chromatographic analysis demonstrates that wines produced by mixed fermentation contain remarkably higher quantities of free monoterpenes and aliphatic esters than wines produced only by commercial strains of Saccharomyces cerevisiae. Differences in the volatile organic compound composition produced sensorially distinct wines. In light of these results, it is possible to state that even within the K. marxianus species it is possible to select strains capable of improving the aromatic quality of wines

Candida zemplinina for Production of Wines with Less Alcohol and More Glycerol

We developed a new protocol for winery mixed fermentations, using the selected Candida zemplinina yeaststrain Cz3. The results of a two-year study, in which red musts (Merlot in 2010; Merlot, Nero d’Avolaand Frappato in 2011) were inoculated with Cz3, is discussed. These wines were compared with winesobtained by inoculation with commercial Saccharomyces cerevisiae yeast strains (NDA21 and AR06 in2010; NDA21 in 2011), or with those obtained by spontaneous fermentation (only in 2011). The inoculationof Cz3 always resulted in a two-phase fermentation: the first phase was driven by the C. zemplinina strain,while the second was dominated by the indigenous S. cerevisiae yeasts coming from the grapes and/or thewinery. In both years the Cz3 wines contained less alcohol and more glycerol than those made with thecommercial yeast strains or those obtained by spontaneous fermentation. Triangle tests showed that asensorial difference between wines could only be achieved through the utilisation of Cz3

Lack of functional redundancy in the relationship between microbial diversity and ecosystem functioning.

1. Biodiversity is declining worldwide with detrimental effects on ecosystems. However, we lack a quantitative understanding of the shape of the relationship between microbial biodiversity and ecosystem function (BEF). This limits our understanding of how microbial diversity depletion can impact key functions for human well-being, including pollutant detoxification. 2. Three independent microcosm experiments were conducted to evaluate the direction (i.e. positive, negative or null) and the shape of the relationships between bacterial diversity and both broad (i.e. microbial respiration) and specialized (i.e. toxin degradation) functions in five Australian and two UK freshwater ecosystems using next-generation sequencing platforms. 3. Reduced bacterial diversity, even after accounting for biomass, caused a decrease in broad (i.e. cumulative microbial respiration) and specialized (biodegradation of two important toxins) functions in all cases. Unlike the positive but decelerating BEF relationship observed most frequently in plants and animals, most evaluated functional measurements were related to bacterial diversity in a non-redundant fashion (e.g. exponentially and/or linearly). 4. Synthesis. Our results suggest that there is a lack of functional redundancy in the relationship between bacterial diversity and ecosystem functioning; thus the consequences of declining microbial diversity on ecosystem functioning and human welfare have likely been considerably underestimated

candida zemplinina for production of wines with less alcohol and more glycerol

We developed a new protocol for winery mixed fermentations, using the selected Candida zemplinina yeast strain Cz3. The results of a two-year study, in which red musts (Merlot in 2010; Merlot, Nero d'Avola and Frappato in 2011) were inoculated with Cz3, is discussed. These wines were compared with wines obtained by inoculation with commercial Saccharomyces cerevisiae yeast strains (NDA21 and AR06 in 2010; NDA21 in 2011), or with those obtained by spontaneous fermentation (only in 2011). The inoculation of Cz3 always resulted in a two-phase fermentation: the first phase was driven by the C. zemplinina strain, while the second was dominated by the indigenous S. cerevisiae yeasts coming from the grapes and/or the winery. In both years the Cz3 wines contained less alcohol and more glycerol than those made with the commercial yeast strains or those obtained by spontaneous fermentation. Triangle tests showed that a sensorial difference between wines could only be achieved through the utilisation of Cz3

Bacterial communities' response to microcystins exposure and nutrient availability : linking degradation capacity to community structure

Eutrophication of freshwater bodies followed by cyanobacterial bloom and toxin production is an important issue in freshwater supply in both developed and developing countries. The primary mechanism for microcystins (MCs) (the main class of cyanobacterial toxins) dissipation is microbial degradation. Repeated exposure of freshwater bodies to cyanobacterial toxins MCs may affect indigenous microbial communities and may also enhance biodegradation of MCs, but the factors driving this relationship remain unclear. Six Scottish freshwater bodies with different histories of natural exposure to MCs and ability to degrade MC-LR (the most common microcystin) were chosen as case study. Terminal Restriction Fragment Length Polymorphism (T-RFLP) and Biolog EcoPlate™ were used to study the structure and physiology of the bacterial communities. Previous exposure to MCs significantly contributed to the bacterial communities shape and microbial physiology of the water bodies under study. Other factors that significantly affected the bacterial communities were dissolved organic carbon and concentration of nitrogen compounds as well as temperature. Moreover a significant relationship was found between bacterial communities' structure and MC-LR half-life. These data suggest that exposure to MCs drives changes in structure and physiology of bacterial communities and in turn those communities differentially perform degradation of MC-LR