Affiliation:
1. Institute of Biodiversity, Johann Heinrich von Thünen-Institut (vTI), Braunschweig, Germany
Abstract
ABSTRACT
Cultivation-independent analyses based on genetic profiling of partial bacterial 16S rRNA genes by PCR-single-strand conformation polymorphism (PCR-SSCP), reverse transcriptase (RT)-PCR-SSCP of the 16S rRNA itself, and stable isotope probing (SIP), followed by RT-PCR-SSCP, were applied to characterize the diversity of metabolically active bacteria in the larval gut of
Manduca sexta
bred on tobacco leaves under greenhouse conditions. For SIP, hatching larvae were fed with leaves from tobacco plants grown in a
13
CO
2
-enriched atmosphere. Dominant SSCP bands were sequenced and phylogenetically analyzed. Only one major gut colonizer, an
Enterococcus
relative, was detected; it occurred in the heavy RNA fraction, demonstrating its metabolic activity, and it originated from eggs, where its metabolic activity was also indicated by rRNA-based SSCP profiles. In contrast, a
Citrobacter sedlakii
relative was detected on eggs by DNA-SSCP, but rRNA-SSCP and SIP-rRNA-SSCP were negative, suggesting that these bacterial cells were inactive. A
Burkholderia
relative was dominant and metabolically active on the tobacco leaves but inactive inside the gut, where it was also quantitatively reduced, as suggested by lower band intensities in the DNA-based SSCP profiles. SIP-RNA-SSCP detected another metabolically active gut bacterium (
Enterobacter
sp.) and more bacteria in the light RNA fraction, indicating low or no metabolic activity of the latter inside the gut. We conclude that the larval gut supported only a low diversity of metabolically active bacteria.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Cited by
70 articles.
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