Filtern
Dokumenttyp
Sprache
- Englisch (5)
Referierte Publikation
- ja (5)
Schlagworte
- Fungi (5) (entfernen)
Organisationseinheit der BAM
Microbial colonization affects the efficiency of photovoltaic panels in a tropical environment
(2015)
Sub-aerial biofilm (SAB) development on solar panels was studied in São Paulo. After 6, 12 and 18 months' exposure, photovoltaic panels were covered by increasing proportions of organic matter (42%, 53% and 58%, respectively). Fungi were an important component of these biofilms; very few phototrophs were found. Major microorganisms detected were melanised meristematic ascomycetes and pigmented bacterial genera Arthrobacter and Tetracoccus. While diverse algae, cyanobacteria and bacteria were identified in biofilms at 6 and 12 months, diversity at a later stage was reduced to that typical for SAB: the only fungal group detected in 18 month biofilm was the meristematic Dothideomycetes and the only phototrophs Ulothrix and Chlorella. Photovoltaic modules showed significant power reductions after 6, 12 (both 7%) and 18 (11%) months. The lack of difference in power reduction between 6 and 12 months reflects the dual nature of soiling, which can result from the deposition of particulates as well as from SAB fouling. Although 12-month old SAB demonstrated an almost 10-fold increase in fungal colonization and a higher organic content, the larger non-microbial particles (above 10 µm), which were important for efficiency reduction of lightly-biofilmed panels, were removed by high rainfall just before the 12-month sampling.
Quantification of microbial load in diesel storage tanks using culture- and qPCR-based approaches
(2016)
Microbial contamination of fuels, associated with a wide variety of bacteria and fungi, leads to decreased product quality and can compromise equipment performance by biofouling and microbiologically influenced corrosion of pipelines and storage tanks. Detection and quantification of biomass are critical in monitoring fuel systems for an early detection of microbial outbreaks. The aims of this study are (i) to quantify bacterial and fungal contamination in samples from diesel storage tanks of petrol stations, using both culture dependent- and culture independent (qPCR) approaches, and (ii) to analyse the diversity of cultivable diesel-contaminating microorganisms with the purpose to create a strain collection for further use in biodeterioration experiments. Both methodological approaches revealed a high microbial contamination in all studied samples, with the bacterial load being much higher than the fungal load. The diversity of cultivable microorganisms was rather low. Based on criteria of abundance and fuel degradation potential, the most relevant microorganisms were identified as bacteria of genera Bacillus, Citrobacter, Burkholderia and Acetobacter, the filamentous fungi Paecilomyces variotii and Pseudallescheria boydii, and a Dipodascaceae yeast. Furthermore the validity and utility of qPCR-based methods are discussed.
Magura Cave, north-western Bulgaria, possesses valuable rock-art paintings made with bat guano and dated from the period between the Eneolithic and Bronze Ages. Since 2008, the Art Gallery is closed to the general public in order to protect the paintings from vandalism, microclimatic changes caused by visitors and artificial illumination, and the consequent growth of fungi and phototrophs. Nevertheless, some tourist visits are allowed under the supervision of cave managers. This study provides the first scientific report on cultivable fungal assemblages dwelling different substrata in the Art Gallery. A total of 78 strains, belonging to 37 OTUs (Ascomycota 81%, Zygomycota 13%, Basidiomycota 5%), were isolated in the study. This fungal diversity was clearly dominated by Penicillium (50% of strains) and Aspergillus (13%). The most relevant visible fungal colonies were detected in sediments rich in bat guano, where, besides Penicillium, other guanophilic fungi such as Mucor, Mortierella, Trichosporon and Trichoderma were dominant. Conversely, scarce fungi were detected on rock surface of painted walls. Based on the biocide susceptibility assay, octylisothiazolinone (OIT) and benzalkonium chloride (BAC) were effective inhibiting the in vitro growth of dominant fungal species in Magura Cave, when applied at concentrations ranged from 100 to 1,000 mg/L. These data provide a valuable knowledge about Magura fungi, and exemplify a type of preliminary test that may be conducted before planning any biocide treatment. However, considering the irreversible effects of biocides on the ecological balance in caves, and the low fungal contamination in painted walls of Magura Cave, there is no reason to use conventional biocides in this cave. Further studies, monitoring microbial communities and microclimatic parameters, should be conducted to improve the knowledge on microbial ecology in Magura Cave and possible human impacts, as well as to allow the early detection of potential microbial outbreaks.
Soiling of photovoltaic (PV) systems compromises their performance causing a significant power loss and demanding periodical cleaning actions. This phenomenon raises great concerns in the solar energy field, thus leading to notable research efforts over the last decades. Soiling is caused by a dual action of dust deposition and biofouling. However, surprisingly, the microbiological contribution to PV soiling is often overlooked or underestimated. In this study, a variety of qPCR-based methods have been developed to quantify the microbial load of fungi, bacteria and phototrophs on PV panels. These protocols were evaluated by comparison with culturedependent methods, and were implemented with real solar plants for two years. The results show that the developed molecular methods are highly sensitive and reliable to monitor the microbial component of the soiling. Fungal biomass was clearly dominant in all analysed PV modules, while bacteria and phototrophs showed much lower abundance. Light microscopy and qPCR results revealed that melanised microcolonial fungi and phototrophs are the main biofilm-forming microorganisms on the studied solar panels. In particular, the fungal qPCR protocol is proposed as a useful tool for monitoring of PV soiling, and investigating the microbial contribution to specific soiling cases.
The development of a test to evaluate the degradation of semi-volatile fuels as diesel by microorganisms is presented. This method is based on the principles described in the CEC-L-103 Standard procedure that is exclusively meant for testing the biodegradability of non-volatile lubricants. Therefore, significant modifications involve aseptic conditions for testing specific microorganisms and conducting the test in closed vessels avoiding evaporation losses, while fuel quantification using gas chromatography-flame ionization detection (GC-FID) is retained. It is suggested that the modified procedure should enable routine application for semi-volatile hydrocarbon-based fuels. GC-FID provides additionally valuable information on the alteration of fuel component patterns during biodegradation. The procedure was successfully tested using two bacteria (Pseudomonas aeruginosa and Sphingomonas sp.) and two yeasts (Moesziomyces sp. and Candida sp.) isolated from real diesel contamination cases. All tested microorganisms caused a significant degradation of diesel fuel achieving hydrocarbon degradation percentages ranging from 23% to 35%. Specific aspects on the test modification and prospects for further modification regarding targeted investigations in the field of fuel contamination by microorganisms are briefly discussed.