From owner-drosophila@net.bio.net Sun May 21 23:00:00 1995 Path: biosci!UHUNIX.UHCC.HAWAII.EDU!tlyttle From: tlyttle@UHUNIX.UHCC.HAWAII.EDU (Terrence Lyttle) Newsgroups: bionet.drosophila Subject: Re: help with food (fwd) Date: 22 May 1995 13:52:25 -0700 Organization: BIOSCI International Newsgroups for Molecular Biology Lines: 38 Sender: daemon@net.bio.net Distribution: world Message-ID: NNTP-Posting-Host: net.bio.net I have two solutions which you might try. I am pretty sure you have a problem with the bacterium leuconostoc. The slime is actually the polysaccharide coat from the bacterium. Solution #1 is to switch to using dextrose as your sugar source. Leuconostoc cannot metabolize dextrose to make the coat, and since it is the coat that is causing the trouble (suffocating the larvae and eggs and dessicating the adults), your cultures should go better. Two problems with this approach are (1) after many generations on this sugar source, many fly strains begin to weaken (a nutritional problem?), and (2) this does not really eliminate the bacterium, so the infection can come back even stronger if you have to switch back to a sucrose based food. The second solution works better in the long run. Spray the surface of your food after it cools with a suspension of the yeast (live) Candida crusiae (you can get this from American Type Culture). This is an excellent food source for Drosophila, grows aggressively, and in our hands, quickly outcompetes the bacterial infection, eliminating it as a problem after only a couple of generations. I recommend this approach highly. We use this Candida strain regularly on our cultures now, and the flies really love it (it smells good to researchers as well!) Please note that this Candida species is not a problem for humans, in particular it does not cause the problem for women that some Candida species are responsible for. Good luck! On Sun, 21 May 1995 delidakis@nefeli.imbb.forth.gr wrote: > The fly group in the IMBB is facing a serious food problem and we'd be very > greatful if you had any suggestions on how to solve it. Basically, our > food works fine if the stock/cross is healthy and we put a good number > of females per vial (6-8 rather than the 1-2 suggested in Kathy Matthews' > recent posting). However, when we go down to 1-3 females of a not so > vigorous strain, the culture becomes overrun by some sort of slime, which > is probably bacteria. A few eggs and 1st instar larvae are usually seen Terry Lyttle Department of Genetics and Molecular Biology University of Hawaii .