Aspects of copper tolerance and toxicity inAmphora coffeaeformis

Abstract

Measurements of photosynthesis, respiration, electron transport activity and ATP were used to locate the site(s) of copper toxicity in the fouling diatom, Amphora coffeaeformis. Results of this and previous research suggest that, except at very high concentrations ( 5 × 10 -6 M), ionic copper does not target these processes, but rather one which occurs at or near the plasmalemma. This may reflect a reduced ability of ionic copper to cross the membranes of the chloroplasts and mitochondria, and possibly the plasmalemma as well. In contrast, copper bound to HQO (8-hydroxyquinoline) or HQA (8-hydroxyquinaldine) was highly toxic to electron transport and ATP production, although the ligands alone had no effect on either process. This supports a membrane-carrier role for HQO and HQA, which give copper access to internal mitochondrial and possibly chloroplast membranes.In a second set of experiments, A. coffeaeformis cells were treated with enzymes in order to elucidate external copper tolerance mechanisms. Cells treated with the polysaccharidase, p-glucuronidase, became more sensitive to copper, whereas those treated with the protease, trypsin, showed improved growth and no increase in sensitivity to copper. This supports a polysaccharide-based tolerance mechanism.

A computational model for microbial colonization of an antifouling surface

“…In reality, of course, we would expect different marine microbial species to show qualitatively different growth and death dynamics, both in the presence and absence of different biocides. A wide range of bacterial, algal and diatomaceous species have been observed to contribute to marine biofilm formation on modern antifouling paint surfaces (see for example Muthukrishnan et al, 2017 ; Winfield et al, 2018 ; Papadatou et al, 2021 ) and an additional factor is the well-known tolerance of some common fouling species (e.g., Amphora coffeaeformis ) to some common biocides (e.g., copper-based compounds) (Callow, 1986 ; Robinson et al, 1992 ). It would be of interest to measure such growth and killing curves for marine organisms exposed to common biocides and biocide combinations and incorporate this data into computational models.…”

Surface sensing and stress-signalling inUlvaand fouling diatoms – potential targets for antifouling: a review

“…Diatoms that are tolerant to Cu, such as Amphora and Navicula, possess Cu-sequestering intracellular bodies that maintain low concentrations of free Cu + in the cells (Daniel & Chamberlain 1981). An additional method of tolerating high Cu levels in A. coffaeaformis is through complexing of EPS polysaccharides with Cu (Robinson et al 1992).…”

TWO DISTINCT COLONIAL MORPHOTYPES OF AMPHORA COFFEAEFORMIS (BACILLARIOPHYCEAE) CULTURED ON SOLID MEDIA1

“…Also, it has become apparent to us that A. coffeapforinis mutants may provide a useful tool to further our knowledge of the copper-tolerance mechanisms in this species. For example, the isolation of mutants unable to produce extracellular polysaccharide could be useful in confirming a role for this copper-binding exudate in copper resistance (Robinson et al 1992). Here we report the characterization of two different colonial morphotypes consistently formed when A. roffeaefonnis grows on solid media.…”