Syntrophy and interspecies electron transfer among different microbial groups occurs in anaerobic digestion, and many papers recently reported their positive effect on biogas and methane production. In this paper, we present the results on the effect of conductive material, i.e., graphene, PAC and biochar addition in 3.5 L batch experiments, analyzing the biogas production curve. A peculiar curve pattern occurred in the presence of conductive materials. Compared to the respective controls, the addition of graphene produced a biogas surplus of 33%, PAC 20% and biochar 8%. Microbial community molecular analysis showed that syntrophic microorganisms present in the inoculum were stimulated by the conductive material addition. Graphene also appears to promote an interspecies electron transfer between Geobacter sp. and ca. Methanofastidiosum. This paper contributes to the understanding of the DIET-related microbial community dynamic in the presence of graphene and PAC, which could be exploited to optimize biogas and methane production in real-scale applications.
Background
The biodiversity of the mycobiota of soft cheese rinds such as Brie or Camembert has been extensively studied, but scant information is available on the fungi colonizing the rinds of cheese produced in the Southern Switzerland Alps. This study aimed at exploring the fungal communities present on rinds of cheese matured in five cellars in Southern Switzerland and to evaluate their composition with regards to temperature, relative humidity, type of cheese, as well as microenvironmental and geographic factors. We used macro- and microscopical morphology, matrix-assisted laser desorption/ionization–time of flight (MALDI-TOF) mass spectrometry, and sequencing to characterize the fungal communities of the cheeses, and compared them with metabarcoding targeting the ITS region.
Results
Isolation by serial dilution yielded 201 isolates (39 yeasts and 162 filamentous fungi) belonging to 9 fungal species. Mucor and Penicillium were dominant, with Mucor racemosus, M. lanceolatus, P. biforme, and P. chrysogenum/rubens being the most frequent species. All but two yeast isolates were identified as Debaryomyces hansenii. Metabarcoding detected 80 fungal species. Culture work and metabarcoding produced comparable results in terms of similarity of the fungal cheese rind communities in the five cellars.
Conclusions
Our study has shown that the mycobiota on the rinds of the cheeses studied is a comparatively species-poor community influenced by temperature, relative humidity, type of cheese, and manufacturing steps, as well as microenvironmental and possibly geographic factors.
The dreissenid quagga mussel, Dreissena rostriformis bugensis, is an invasive species native to the Black Sea region that has recently spread to Western Europe. This organism has recently colonized Swiss northern perialpine lakes, causing major changes to aquatic ecosystems and impacts on human activities. Due to its competitiveness, the quagga mussel takes advantage of human mediated transport to reach new environments. Therefore, the management of quagga mussel should seek to prevent further spread and minimize its negative impact. With this aim, the early detection by environmental DNA (eDNA) methods is increasingly applied in freshwater systems. Here, an approach based on species-specific primer targeting the quagga mussel from eDNA was applied to Lake Lugano and Lake Maggiore, two large perialpine lakes at risk of invasion due international tourism. Our results are the first to show that the quagga mussel has spread south of the Alps and suggest that in both the lakes the colonization is in the early stages. Additionally, they indicate that the eDNA approach is a powerful tool for the early detection of quagga mussel invasions, and may be applied to reduce the resulting ecological and economic impacts.
The quagga mussel Dreissena rostriformis bugensis is an invasive species that has recently spread to Western Europe, causing major impacts on aquatic ecosystems and human activities. We considered lakes Lugano and Maggiore (Ticino River basin, Italy and Switzerland) to be at high risk of colonization due to leisure boat traffic from already-colonized lakes. We performed an environmental DNA based survey to detect any quagga mussel invasions in these lakes as early as possible. The results of the survey confirmed the presence of this species in the lakes and support the use of molecular approaches for the early detection of invasive mussels.
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