Necrotrophic growth of legionella pneumophila

This study examined whether Legionella pneumophila is able to thrive on heat-killed microbial cells (necrotrophy) present in biofilms or heat-treated water systems. Quantification by means of plate counting, real-time PCR, and flow cytometry demonstrated necrotrophic growth of L. pneumophila in water after 96 h, when at least 100 dead cells are available to one L. pneumophila cell. Compared to the starting concentration of L. pneumophila, the maximum observed necrotrophic growth was 1.89 log units for real-time PCR and 1.49 log units for plate counting. The average growth was 1.57 ± 0.32 log units (n = 5) for real-time PCR and 1.14 ± 0.35 log units (n = 5) for plate counting. Viability staining and flow cytometry showed that the fraction of living cells in the L. pneumophila population rose from the initial 54% to 82% after 96 h. Growth was measured on heat-killed Pseudomonas putida, Escherichia coli, Acanthamoeba castellanii, Saccharomyces boulardii, and a biofilm sample. Gram-positive organisms did not result in significant growth of L. pneumophila, probably due to their robust cell wall structure. Although necrotrophy showed lower growth yields compared to replication within protozoan hosts, these findings indicate that it may be of major importance in the environmental persistence of L. pneumophila. Techniques aimed at the elimination of protozoa or biofilm from water systems will not necessarily result in a subsequent removal of L. pneumophila unless the formation of dead microbial cells is minimized

Zuiver water en biomassa dankzij algenteelt

Algenteelt heeft grote toekomstmogelijkheden, maar welke soorten en welke teeltsystemen zijn technisch en economisch haalbaar en ecologisch interessant in Noordwest-Europa? Dit wordt de komende jaren binnen het project Energetic Algae onderzocht. In dit dossier 4 artikelen over algenteelt: 1) Is algenteelt bij ons een haalbare kaart? 2) van micro tot macro, van zoet tot zout. 3) Op bezoek bij Nederlandse algentelers, o.a. het onderzoekscentrum AlgaePARC, algenvijvers van het landbouwbedrijf Kelstein en het praktijkcentrum Acrres. 4) Eerste Vlaamse algenvijver gestart

The bacterial storage compound poly-ß-hydroxybutyrate protects <i>Artemia franciscana</i> from pathogenic <i>Vibrio campbellii</i>

Infections caused by antibiotic-resistant luminescent Vibrios can cause dramatic losses in aquaculture. In this study, the short-chain fatty acid &#x03B2;-hydroxybutyrate and its polymer poly-&#x03B2;-hydroxybutyrate were investigated as possible new biocontrol agents. &#x03B2;-Hydroxybutyrate was shown to completely inhibit the growth of pathogenic Vibrio campbelli at 100&nbsp;mM. Moreover, the addition of 100&nbsp;mM of this fatty acid to the culture water of Artemia nauplii infected with the V.&nbsp;campbelli strain significantly increased the survival of the nauplii. As Artemia is a non-selective and particle filter feeder, we also investigated whether poly-&#x03B2;-hydroxybutyrate particles could be used to protect Artemia from the pathogenic V.&nbsp;campbellii. The addition of 100&nbsp;mg&nbsp;l1 poly-&#x03B2;-hydroxybutyrate or more to the Artemia culture water offered a preventive and curative protection from the pathogen as a significantly enhanced survival was noticed. If added as a preventive treatment, a complete protection of infected nauplii (no significant mortality compared with uninfected nauplii) was observed at 1000&nbsp;mg&nbsp;l1 poly-&#x03B2;-hydroxybutyrate. Our data indicate that the use of poly-&#x03B2;-hydroxybutyrate might constitute an ecologically and economically sustainable alternative strategy to fight infections in aquaculture

Failure of the ammonia oxidation process in two pharmaceutical wastewater treatment plants is linked to shifts in the bacterial communities W.

Aims: To investigate whether two different wastewater treatment plants (WWTPs) – treating the same pharmaceutical influent – select for a different bacterial and/or ammonia oxidizing bacterial (AOB) community. Methods and Results: Molecular fingerprinting demonstrated that each WWTP had its own total bacterial and AOB community structure, but Nitrosomonas eutropha and N. europea were dominant in both WWTP A and B. The DNA and RNA analysis of the AOB communities revealed different patterns; so the most abundant species may not necessarily be the most active ones. Nitritation failures, monitored by chemical parameter analysis, were reflected as AOB community shifts and visualized by denaturing gradient gel electrophoresis (DGGE)-based moving window analysis. Conclusions: This research demonstrated the link between functional performance (nitritation parameters) and the presence and activity of a specific microbial ecology (AOB). Clustering and moving window analysis based on DGGE showed to be valuable to monitor community shifts in both WWTPs. Significance and Impact of the Study: This study of specific community shifts together with functional parameter analysis has potential as a tool for relating functional instability (such as operational failures) to specific-bacterial community shifts

Biogas properties and enzymatic analysis during anaerobic fermentation of Phragmites australis straw and cow dung: influence of nickel chloride supplement

This work was funded by the National Special Water Programs (Nos. 2009ZX07210-009, 2015ZX07203-011, 2015ZX07204-007), Ecological Safety Survey and Assessment of Nansi Lake (2012–2015), Ecological Riverway Artificial Strengthen Key Technology Research and Demonstration Project of Shandong Province (2012–2014, SDHBPJ-ZB-08), the China Scholarship Council (No. 201406730018)