Monitoring of the evolving diversity of the microbial community present inrotifer cultures

The genetic fingerprint of the microbiota in the culture water of two diffe rent rotifer culture systems (batch versus recirculation) was obtained by m eans of denaturing gradient gel electrophoresis (DGGE) of 165 rRNA gene fra gments. The genetic profile of the bacterial community present in the cultu re water of a batch culture system changed daily due to shifts occurring at the level of the dominance of bands. By means of statistical tools, it was possible to distinguish three different periods during the development of the microbiota in the recirculation experiment, each corresponding to a typ ical period during the production of rotifers. overall, it was obvious that the microbiota in such a recirculation system was less susceptible for var iation relative to the microbiota in a batch system. However, some shifts i n the genetic profile were observed when technical problems occurred result ing in a reduced water quality or performance of the biofilter. Characterisation of the microbial community present in the recirculation sy stem indicated that the sequences of typical bands showed the highest level of identity to the sequences from the bacterial strain MM8-1(T) (represent ing a species in the genus Marinomonas, Marinomonas mediterranea sp.), M, v aga and Pseudoalteromonas haloplanktis spp. tetraodonis strain IAM 14160 (9 8%). (C) 2001 Elsevier Science B.V. All rights reserved.