AUTHOR=Zeleke Jemaneh , Sheng Qiang , Wang Jian-Gong , Huang Ming-Yao , Xia Fei , Wu Ji-Hua , Quan Zhe-Xue 

TITLE=Effects of Spartina alterniflora invasion on the communities of methanogens and sulfate-reducing bacteria in estuarine marsh sediments

JOURNAL=Frontiers in Microbiology

VOLUME=4

YEAR=2013

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2013.00243

DOI=10.3389/fmicb.2013.00243

ISSN=1664-302X

ABSTRACT=<p>The effect of plant invasion on the microorganisms of soil sediments is very important for estuary ecology. The community structures of methanogens and sulfate-reducing bacteria (SRB) as a function of <italic>Spartina alterniflora</italic> invasion in <italic>Phragmites australis-vegetated</italic> sediments of the Dongtan wetland in the Yangtze River estuary, China, were investigated using 454 pyrosequencing and quantitative real-time PCR (qPCR) of the methyl coenzyme M reductase A (<italic>mcrA</italic>) and dissimilatory sulfite-reductase (<italic>dsrB</italic>) genes. Sediment samples were collected from two replicate locations, and each location included three sampling stands each covered by monocultures of <italic>P. australis, S. alterniflora</italic> and both plants (transition stands), respectively. qPCR analysis revealed higher copy numbers of <italic>mcrA</italic> genes in sediments from <italic>S. alterniflora</italic> stands than <italic>P. australis</italic> stands (5- and 7.5-fold more in the spring and summer, respectively), which is consistent with the higher methane flux rates measured in the <italic>S. alterniflora</italic> stands (up to 8.01 ± 5.61 mg m<sup>−2</sup> h<sup>−1</sup>). Similar trends were observed for SRB, and they were up to two orders of magnitude higher than the methanogens. Diversity indices indicated a lower diversity of methanogens in the <italic>S. alterniflora</italic> stands than the <italic>P. australis</italic> stands. In contrast, insignificant variations were observed in the diversity of SRB with the invasion. Although <italic>Methanomicrobiales</italic> and <italic>Methanococcales</italic>, the hydrogenotrophic methanogens, dominated in the salt marsh, <italic>Methanomicrobiales</italic> displayed a slight increase with the invasion and growth of <italic>S. alterniflora</italic>, whereas the later responded differently. <italic>Methanosarcina</italic>, the metabolically diverse methanogens, did not vary with the invasion of, but <italic>Methanosaeta</italic>, the exclusive acetate utilizers, appeared to increase with <italic>S. alterniflora</italic> invasion. In SRB, sequences closely related to the families <italic>Desulfobacteraceae</italic> and <italic>Desulfobulbaceae</italic> dominated in the salt marsh, although they displayed minimal changes with the <italic>S. alterniflora</italic> invasion. Approximately 11.3 ± 5.1% of the <italic>dsrB</italic> gene sequences formed a novel cluster that was reduced upon the invasion. The results showed that in the sediments of tidal salt marsh where <italic>S. alterniflora</italic> displaced <italic>P. australis</italic>, the abundances of methanogens and SRB increased, but the community composition of methanogens appeared to be influenced more than did the SRB.</p>