Do some catfish really eat wood?

[Jost]

Zitat von Suckermouth Jo

Hallo
Vor Donovan haben Nelson et al, J. Fish Bio. 1999 schon das Thema angepackt und kamen insofern zu einem anderen Resultat, als dass sie "significant cellulolytic activity" bei Kulturen von Panaque Darmflora fanden
Gruss

..... wobei man aber Zweifel an deren experimentellen Design haben darf, meine Interpretation dieser Ergebnisse war damals und ist heute die gleiche wie auch German diskutiert (1 Zitat aus German 2009, zweites aus German & Bittong 2009):

" Given that Nelson et al. (1999) were only able to isolate
aerobic and facultatively anaerobic microbes from the guts
of Panaque and Pterygoplichthys, it is probable that these
microorganisms are transient and consumed with detritus
rather than representing an endosymbiotic community."

und

"The cellulase activities measured in this study are three
orders of magnitude lower than those reported for Panaque
maccus and Pterygoplichthys sp. by Nelson et al. (1999).
However, there are several methodological differences
between this study and that performed by Nelson et al.
First, they used assay conditions designed for ruminant
mammals (pH 5, 40°C), which differ from the conditions in
the fishes’ guts. We designed our assay conditions to reflect
the fishes’ gut pH (pH 7.5; Table S1) and ambient temperatures
of their environment (25°C). Second, Nelson et al.
(1999) did not specify in which region of the gut they measured
the enzyme activities. Third, when performing a general
reducing sugar assay for polysaccharidase activity that
includes intestinal contents (as was done by Nelson et al.
and in this study), it is essential to perform appropriate
blanks to account for background reducing sugars in the
gut, and also for additional substrate that may be a source
of other reducing sugars released during the assay (Skea
et al. 2005; German et al. 2009). Not doing so will result in
an over-estimation of activity levels; Nelson et al. did not
perform this type of blank with their assays. Fourth, the
activities were likely calculated differently between the two
studies. Thus, direct comparisons of enzymatic activity
levels between this study and that of Nelson et al. (1999)
are impossible."