ROLE OF MICROBIAL LOOP IN AQUATIC CARBON AND NITROGEN CYCLES

微生物循环在水生碳和氮循环中的作用

基本信息

批准号：
05454603
负责人：
YOSHIOKA Takahito
金额：
$ 4.29万
依托单位：
NAGOYA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1993
资助国家：
日本
起止时间：
1993 至 1994
项目状态：
已结题

项目摘要

The purpose of this study was to examine the role of microbial food webs in the carbon and nitrogen cycling within pelagic environments of freshwater lakes. Studies were categorized in three categories. (1) Mechanism of ammonia regeneration and its controlling factor, (2) Mechanism of bacterial decomposition and utilization of dissolved organic nitrogen, and (3) Food web analysis using stable isotope ratios. We, thus, analyzed the role of microbial loo p on C and N cycles with interdisciprinary approaches (microbiological and geochemical ones). We particularly focused on mechanisms of ammonium regeneration and bacterial utilization of dissolved organic matter (DOM). Measurements of size-fractionated NH4 regeneration in mesotrophic Lakes Kizaki and Biwa revealed that bacteria and bacterivores contribute substantially to total NH4 regeneration ; up to 80% of NH4 regeneration was attributable to heterotrophs in the <20mum fraction. Bacteria appeared to be a source rather than a sink of NH4 in the study area. To further examine the regulation of carbon and nitrogen metabolism by freshwater bacteria, we measured concentrations and bacterial utilization of dissolved free (DFAA) and combined amino acids (DCAA) in Lake Biwa.Preliminary results suggested that DCAA rather than DFAA were the major source of organic nitrogen for bacteria. Our results demonstrate that carbon and nitrogen fluxes driven by the microbial loop play the key role in ecosystem functioning and community dynamics in freshwater environments.

这项研究的目的是检查微生物食物网在淡水湖中浮游环境中碳和氮循环中的作用。研究分为三类。（1）氨再生机制及其控制因子，（2）细菌分解和利用溶解有机氮的机制，以及（3）使用稳定同位素比的食物网分析。因此，我们通过跨学科方法（微生物和地球化学方法）分析了微生物loo p对C和N周期的作用。我们尤其专注于铵再生的机制和溶解有机物（DOM）的细菌利用。在kizaki和biwa中，测量大小的NH4再生的测量结果表明，细菌和细菌疗法对总NH4再生有很大贡献。 NH4再生的80％归因于<20MUM分数中的异嗜性。在研究区域中，细菌似乎是NH4的来源，而不是NH4的水槽。为了进一步检查淡水细菌对碳和氮代谢的调节，我们测量了Biwa湖中溶解的游离（DFAA）和氨基酸（DCAA）的浓度和细菌利用。预测结果表明DCAA而不是DFAA而不是DFAA是有机氮的主要来源。我们的结果表明，由微生物环驱动的碳和氮通量在淡水环境中的生态系统功能和社区动态中起关键作用。