Copper accumulation by bacteria and transfer to scallop larvae

Area of Science:

• Marine Microbiology
• Environmental Toxicology
• Bacterial Physiology

Background:

• Copper resistance in marine bacteria is crucial for understanding heavy metal dynamics.
• Scallops (Argopecten purpuratus) are filter feeders susceptible to environmental contaminants.
• Bacterial accumulation of metals can influence their bioavailability and transfer through food webs.

Purpose of the Study:

• To isolate and identify a copper-resistant bacterium from scallops.
• To quantify copper accumulation by the isolated Vibrio sp.
• To assess copper transfer from bacteria to scallop larvae.

Main Methods:

• Isolation and physiological characterization of a copper-resistant bacterial strain from Argopecten purpuratus.
• Determination of minimum inhibitory concentration (MIC) of Cu2+ for the Vibrio strain.
• Quantification of cellular and loosely bound copper accumulation by Vibrio sp. using atomic absorption spectroscopy.
• Exposure of scallop larvae to copper-enriched Vibrio and measurement of accumulated copper.

Main Results:

• A copper-resistant Vibrio sp. was isolated, with complete inhibition at 50 microg ml(-1) Cu2+.
• The Vibrio strain accumulated high levels of copper (201.14 microg g(-1) dry weight cellular, 493.21 microg g(-1) dry weight loosely bound) after 24h exposure.
• Scallop larvae exposed to copper-enriched Vibrio accumulated significant amounts of copper (20.42-30.96 microg g(-1) dry weight).

Conclusions:

• Bacterial copper accumulation is a significant process in marine environments.
• Copper-resistant bacteria can act as vectors for copper transfer to marine organisms.
• This bacterial-mediated transfer can increase copper's presence in marine food chains.