Date: 13 Nov 1997
From: "Dennis T. Walsh" <dwalsh@capecod.net>
To: aqua-l-digest@killick.ifmt.nf.ca
COMMENTS 1:
I do not recommend to use antibiotics to remove pathogenic bacteria from algae cultures. My experience with algae over the last 15 years is that the use of antibiotics only leads to the selection of more virulent strains of pathogenic bacteria. The regular use of antibiotics in stock algal cultures should not be done. I routinely maintained axenic cultures of diatoms and phytoflagellates by periodically reisolating the microalgae on agarose media.
FMC Bioproducts (5 Maple St., Rockland, ME 04841-2944. Telephone: 1-800-341-1574; technical service: 1-800-341-1574) has SeaPlaque and SeaPrep agarose that have low gelling and melting temperatures that are ideal for isolating algae. SeaPlaque is usually fine for isolation of diatoms and flagellates; if the alga is particularly sensitive to temperature use SeaPrep.
Individual colonies of algae on the agarose can be reisolated into sterile algal media using micropipets. A good reference on this technique is found in:
Stein, J.R. 1973. Handbook of Phycological Methods, Culture Methods and Growth Measurements. Cambridge University Press, London.
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COMMENTS 2:
Date: 14 Nov 1997
From: Steve Morton <SMorton@bigelow.org>
To: AQUA-L@killick.ifmt.nf.ca
I agree that antibiotics should not be used in routine maintenance of cultures. However, with good aseptic techniques, axenic algal cultures can remain bacterial-free for years. Here at the Provasoli-Guillard National Center for Culture of Marine Phytoplankton (CCMP), we have maintained cultures in an axenic state since 1956. These cultures are tested for bacteria every six months. This includes all the "common" food algae (ie: 3H, T-ISO, ACTIN, DUN, etc.) used in most hatcheries. For more information about the CCMP visit our web page at
http://ccmp.bigelow.org.
The latest reference on culture techniques written by Dr. Robert Guillard can be found in "Manual on Harmful Marine Microalgae" (1995), published by UNESCO, pp. 45-62.
Steve Morton
Curator, CCMP
Provasoli-Guillard National Center for Culture of Marine Phytoplankton
Bigelow Laboratory for Ocean Sciences
West Boothbay Harbor, ME 04575, USA
e-mail: SMorton@bigelow.org
phone: (207) 633-9626 FAX: (207) 633-9715
web page: http://ccmp.bigelow.org