近日，国家著名杂志Applied Microbiology and Biotechnology刊登了中科院亚热带农业生态研究所研究人员的研究成果“Long-term field fertilization alters the diversity of autotrophic bacteria based on the ribulose-1,5-biphosphate carboxylase/oxygenase (RubisCO) large-subunit genes in paddy soil。”，文章中，研究人员揭示了长期施肥对土壤固碳细菌群落结构、多样性及数量均有显著的影响。
生物固碳是陆地生态系统中最直接有效的二氧化碳固定途径，其中具有固碳功能的微生物分布广泛，它们有很强的环境适应能力。从整个生物圈的物质、能量流来看，二氧化碳的微生物固定是一支绝不容忽视的生物固碳力量。因此，研究微生物固定二氧化碳的生态环境效应具现实意义。
cbbL基因编码的核酮糖-1, 5-二磷酸梭化酶/加氧酶（RubisCO）是卡尔文循环中的关键酶，该酶催化卡尔文循环中的第一步CO2固定反应。然而，目前关于固碳自养菌cbbL基因的分子生态学研究主要集中在旱作系统，对于稻田土壤，特别是长期不同施肥制度对稻田土壤固碳自养菌群落及多样性影响的研究未见报道。
中科院亚热带农业生态研究所研究员吴金水研究组以湖南宁乡、桃江、望城国家级稻田肥力变化长期定位试验为平台，采用PCR-克隆测序和实时荧光定量（Real-time）PCR技术，研究不施肥（CK），氮磷钾肥（NPK）和秸秆还田（NPKS）3种长期施肥制度对稻田土壤固碳自养菌群落结构及数量的影响。
通过分析固碳细菌cbbL基因文库发现，三个地点的cbbL含有的细菌群落以兼性自养菌为主，如沼泽红假单胞菌，Bradyrhizobium japonicum和氧产碱杆菌。长期施肥导致土壤固碳自养菌种群结构产生了明显差异，NPK和NPKS处理中兼性自养固碳菌群落优势增加，而严格自养固碳菌生长受到抑制。细菌cbbL基因拷贝数（3–8×108 copies g soil-1）与稻田土壤固碳关键酶Rubisco活性（0.40–1.76 nmol CO2 g soil-1min-1）活性呈显著相关性，并且随着施肥量的增加而增大。ACC分析表明，土壤有机碳含量和pH是细菌cbbL群落组成、丰度、多样性等最重要的影响因子。
上述结果表明长期施肥对土壤固碳细菌群落结构、多样性及数量均有显著的影响。本研究结果可为深入探讨稻田土壤微生物固碳潜力及其影响机理提供有力的依据。该研究组的博士研究生袁红朝是该论文的第一作者。该研究得到了中国科学院、国家外国专家局创新团队国际合作伙伴计划、国家自然科学基金委和中科院知识创新工程青年人才领域前沿项目的资助。(生物谷Bioon.com)
doi:10.1007/s00253-011-3760-y
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Long-term field fertilization alters the diversity of autotrophic bacteria based on the ribulose-1,5-biphosphate carboxylase/oxygenase (RubisCO) large-subunit genes in paddy soil。
Hongzhao Yuan, Tida Ge, Xiaohong Wu, Shoulong Liu, Chengli Tong, Hongling Qin, Minna Wu, Wenxue Wei and Jinshui Wu
Many mutations, including those that cause disease, only have a detrimental effect in a subset of individuals. The reasons for this are usually unknown, but may include additional genetic variation and environmental risk factors1. However, phenotypic discordance remains even in the absence of genetic variation, for example between monozygotic twins2, and incomplete penetrance of mutations is frequent in isogenic model organisms in homogeneous environments3, 4. Here we propose a model for incomplete penetrance based on genetic interaction networks5, 6. Using Caenorhabditis elegans as a model system, we identify two compensation mechanisms that vary among individuals and influence mutation outcome. First, feedback induction of an ancestral gene duplicate differs across individuals, with high expression masking the effects of a mutation. This supports the hypothesis that redundancy is maintained in genomes to buffer stochastic developmental failure7. Second, during normal embryonic development we find that there is substantial variation in the induction of molecular chaperones such as Hsp90 (DAF-21). Chaperones act as promiscuous buffers of genetic variation8, 9, and embryos with stronger induction of Hsp90 are less likely to be affected by an inherited mutation. Simultaneously quantifying the variation in these two independent responses allows the phenotypic outcome of a mutation to be more accurately predicted in individuals. Our model and methodology provide a framework for dissecting the causes of incomplete penetrance. Further, the results establish that inter-individual variation in both specific and more general buffering systems combine to determine the outcome inherited mutations in each individual.
