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Distribution
Published in Paul Pumpens, Single-Stranded RNA Phages, 2020
Even more intriguingly, metagenomic sequencing revealed the presence of the Leviviridae sequences on Livingston Island (Antarctic Peninsula), especially on the lysis plaque-like macroscopic blighted patches within the predominant microbial mats (Velázquez et al. 2016). Those blighting circles were associated with decay in physiological traits in the spatial microstructure and were evidenced at a time of unprecedented rates of local warming in the Antarctic Peninsula area.
The role of iron-oxidizing bacteria in biocorrosion: a review
Published in Biofouling, 2018
Chemolithoautotrophic Fe-oxidizing bacteria (FeOB) can meet their energy requirements through the oxidation of Fe(II), fix CO2 and respire with O2 as an electron acceptor. They can be broadly classified into two physiological types, acidophiles and neutrophiles (Hedrich et al. 2011). Acidophilic FeOB generally grow at pH 4 or below. At this pH, soluble Fe(II) is stable in the presence of O2, and these bacteria grow prolifically. However, these environments are relatively rare, especially in terms of places where steel infrastructure is found, and so will not be considered further here. FeOB that grow in more circumneutral conditions, pH 5–8, are common in natural settings where iron is abundant in sediments and soils (Kappler et al. 2016). Chemical oxidation of Fe(II) with O2 becomes rapid with increasing pH, thus these organisms prefer anoxic-oxic mixing regions where O2 concentrations are low, typically <100 µM, and Fe(II) concentrations may exceed 10 µM (Rentz et al. 2007). Under such conditions it is common to find outgrowths of lithotrophic FeOB, where they often manifest themselves in microbial mats that range from being barely visible to centimeters or more thick (Chan et al. 2016). Phylogenetically, the most abundant lithotrophic FeOB in Fe(II)-rich systems delineate themselves quite clearly depending upon whether they live in marine or freshwater environments. The former will be considered first.
Anti-biofilm effect of a butenolide/polymer coating and metatranscriptomic analyses
Published in Biofouling, 2018
Wei Ding, Chunfeng Ma, Weipeng Zhang, Hoyin Chiang, Chunkit Tam, Ying Xu, Guangzhao Zhang, Pei-Yuan Qian
In addition, it is worthwhile noting that the taxonomic composition is similar to that observed in a previous study (Chung et al. 2010), where biofilms were developed at the same location in Hong Kong Water. In the study by Chung et al. (2010), the subtidal biofilms were also dominated by Actinobacteria, Bacteroidetes and Proteobacteria, while the Proteobacteria were composed of Alpha, Beta, Gamma, Delta and Epsilon groups. One exception was the Thaumarchaeota, which accounted for 2–8% in the biofilms in the present study, but were absent in the study of Chung et al. (2010). One explanation is that the technique used by Chung et al. (2010) in community profiling (denaturing gradient gel electrophoresis) did not provide as much in-depth analysis of the microbial community as revealed by high-throughput sequence technique. Members of the Thaumarchaeota have been reported to be dominant in the microbial mats (can generally be seen as ‘larger biofilms’) in Shark Bay, Australia (Wong et al. 2017), and thus members of the Thaumarchaeota could also be inhabitants of the subtidal biofilms.
The oceans are changing: impact of ocean warming and acidification on biofouling communities
Published in Biofouling, 2019
Sergey Dobretsov, Ricardo Coutinho, Daniel Rittschof, Maria Salta, Federica Ragazzola, Claire Hellio
Marine bacteria coordinate virulence, competence, conjugation, production of antibiotics, motility and biofilm formation by quorum sensing (QS) (Miller and Bassler 2001; Waters and Bassler 2005; Williams 2007). QS is based on the production, release and detection of chemical signal molecules called autoinducers. Increased concentrations of these signals due to high bacterial population density lead to an alteration in gene expression that regulates bacterial physiological activities (Decho et al. 2011). One of the most common and studied class of QS signal molecules is acyl homoserine lactone (AHL) (Waters and Bassler 2005). AHLs are unstable at > pH 7 (Yates et al. 2002). Studies assessing the stability of AHL against alkaline hydrolysis showed that AHLs having longer acyl chains (>12 carbons) are more resistant to breakdown than their shorter counterparts (Hmelo et al. 2011). In laboratory and field experiments, pH has been found to have a significant impact on the concentration of AHLs in microbial mats (Decho et al. 2009). In phototrophic microbial mats, short chain AHLs degrade quickly during the day, when the pH is >8.2. During the night, when the pH is 6.8 the concentrations of AHLs increases (Decho et al. 2009). When shorter-chain AHLs are degraded too rapidly, cellular communication may be disrupted. Acidification due to climate change will have a substantial effect on the concentration of AHLs (Table 1). Since AHLs are important for biofilm structure and the composition and settlement of some macrofouling species (Dobretsov et al. 2009), it is possible that changes in the production of QS compounds will alter the density and composition of biofouling communities.