Raja S, Thangaradjou T, Sivakumar K, Kannan L
Centre of Advanced Studies in Marine Biology, Faculty of Marine Sciences, Annamalai University, Parangipettai-608 502, India.
J Environ Biol. 2012 Nov;33(6):1033-7.
Seagrass rhizosphere generally supports high bacterial population density which plays a major role in determining the nutrient cycles of the sea. Higher densities of total heterotrphic bacteria (26.3 x 10(6) CFU g(-1)), nitrogen fixing (27.3 x 10(3) CFUg(-1), ammonifying (44.66 x 10(6) MPN g(-1)) and nitrifying bacteria (42.33 X 10(6) MPN g(-1)) have been registered in the seagrass areas than the non seagrass area. In particular, all these rhizosphere microbial population was higher in Thalassia hemprichii. The rates of nitrogen fixation was recorded in the different species of seagrasses such as Enhalus acoroides (1.166 n mol g(-1) d(-1)), Halophila ovalis (0.166 n mol g(-1) d(-1)), Thalassia hemprichii(18.5 n mol g(-1) d(-1)), Cymodocea serrulata (10.5 n mol g(-1) d(-1)), Halodule uninervis (5.375 n mol g(-1) d(-1)) and Syringodium isoetifolium (0.666 n mol g(-1) d(-1)) using gas chromatography. The average nitrogen fixation by the seagrasses of Gulf of Mannar alone was estimated to be 7640.58 n mol m(-2) d(-1) and the contributions from the rhizosphere microbes will increase the quantity to many fold.
海草根际通常支持高细菌种群密度，这在决定海洋营养循环方面发挥着重要作用。与非海草区域相比，海草区域中总异养细菌（26.3×10⁶ CFU g⁻¹）、固氮细菌（27.3×10³ CFU g⁻¹）、氨化细菌（44.66×10⁶ MPN g⁻¹）和硝化细菌（42.33×10⁶ MPN g⁻¹）的密度更高。特别是，在亨氏海草中，所有这些根际微生物种群数量更高。使用气相色谱法记录了不同种类海草的固氮速率，如伊乐藻（1.166 n mol g⁻¹ d⁻¹）、卵叶喜盐草（0.166 n mol g⁻¹ d⁻¹）、亨氏海草（18.5 n mol g⁻¹ d⁻¹）、锯齿泰来草（10.5 n mol g⁻¹ d⁻¹）、无叶脉盐藻（5.375 n mol g⁻¹ d⁻¹）和异叶丝粉藻（0.666 n mol g⁻¹ d⁻¹）。仅马纳尔湾的海草平均固氮量估计为7640.58 n mol m⁻² d⁻¹，根际微生物的贡献将使这一数量增加许多倍。
