Skip to main content

Caecal fermentation, putrefaction and microbiotas in rats fed milk casein, soy protein or fish meal


To clarify the effect of soy protein (SP) and fish meal (FM), compared to milk casein (MC), on the intestinal environment, we examined caecal environment of rats fed the test diets. Four-week-old rats were fed AIN-76-based diet containing 20 %, w/w MC, SP or FM for 16 days. Caecal organic acids were analysed by HPLC. Caecal putrefactive compounds (indole, phenol, H2S and ammonia) were analysed by colorimetric assays. Caecal microflora was determined by 16S rRNA gene-DGGE and pyrosequencing with bar-coded primers targeting the bacterial 16S rRNA gene. n-Butyric and lactic acid levels were high in rats fed SP and FM, respectively. Butyrate-producing bacteria, such as Oscillibacter, and lactate-producing bacteria, such as Lactobacillus, were detected in each diet group. Also, the putrefactive compound contents were high in rats fed SP and FM. In this study, both DGGE and pyrosequencing analyses were able to evaluate the dynamics of the intestinal microbiota. The results indicate that dietary proteins can alter the intestinal environment, affecting fermentation by the intestinal microbiota and the generation of putrefactive compounds.

This is a preview of subscription content, access via your institution.

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5


Download references


The present study was supported in part by the Ministry of Education, Science, Sports and Culture, Japan, Grant-in-Aid for Scientific Research (C), # 25450300, 2013–2015, and was also supported by a 2013 Grant from Fuji Foundation for Protein Research (Osaka, Japan).

Author information

Authors and Affiliations


Corresponding author

Correspondence to Takashi Kuda.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

An, C., Kuda, T., Yazaki, T. et al. Caecal fermentation, putrefaction and microbiotas in rats fed milk casein, soy protein or fish meal. Appl Microbiol Biotechnol 98, 2779–2787 (2014).

Download citation

  • Received:

  • Revised:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:


  • Casein
  • Soy protein
  • Fish meal
  • Pyroseqeuncing
  • Gut microbiota