Effects of rearing temperature and dietary saccharides on the production of gases and organic acids by gut microbes of an omnivorous teleost, carp Cyprinus carpio, in micro-scale batch cultures

摘要

We studied metabolism of carp Cyprinus carpio gut microbes by measuring gas productivity and net organic acids production from gut contents of this fish using a 50 mu l-scale batch culture system. Intestinal contents of the carp reared at 15 deg C or 25 deg C were incubated with glucose, lactosucrose, sodium alginate or colloidal chitin, (each 10 g/l) at 15 deg C or 25 deg C for 12 h. Levels of organic acids at 12 h of incubation were quantified with HPLC. Types of substrate, rearing and incubationtemperature affected the amount of released gas and organic acid production. We detected higher levels of lactic and iso-valeric acids in cultures of gut contents offish reared at 15 deg C than those at 25 deg C did. More succinic, formic and acetic acids were produced in cultures of gut contents reared at 15 deg C when incubated at 15 deg C than at 25 deg C. More amount of lactic acid was produced in cultures with glucose than in those with lactosucrose, colloidal chitin or none. The level of total organic acids was less in cultures with sodium alginate and colloidal chitin than in blank cultures. These results indicated that the hindgut microbes of the carp are able to utilize various saccharides to produce organic acids and rearing temperature of the host fish affects microbial digestion of these saccharides.