CAREER: Investigating the relationship between giant sulfur bacteria and microfossil-bearing phosphorites.

磷酸盐矿床以其对软组织的精美保存而闻名。包括化石细胞。印度中部Vindhyan盆地16亿年前的磷岩中保存着被认为是最古老的真核生物的大分隔细丝，而中国南部6亿年前的窦山沱组中保存着被认为是最古老的后生动物的磷酸化对称细胞团。有趣的是，大液泡型硫氧化细菌被认为介导了现代磷素发生，并且通常具有与vinhyan细丝和陡山坨球状微化石非常相似的形态。温德海扬或孤山坨微化石是否代表液泡化硫细菌，而不是真核生物？这些微化石是否能证明古代硫细菌对磷的调解作用？以陡山沱群的微生物群为例，有些微化石显然是真核生物，起源上可能是后生动物，而另一些则不能轻易解释为动物。但是细菌和动物的解释是相互排斥的吗？其他古代和近代的磷矿沉积物也具有很可能代表硫细菌化石的结构，但识别它们的标准尚未建立。π吗?美国研究小组将：1)研究新发现的部分埋藏在磷矿物中的现代硫细菌；2)利用现代硫菌进行磷化实验，研究磷化菌的分类；3)将现代磷化硫细菌与元古宙和显生宙磷岩的古微化石进行比较；4)利用对现代硫细菌的观察，建立区分巨型硫细菌化石与微生物真核生物（包括胚胎后生动物）化石的新标准。该提案的研究部分与教育和拓展计划密切相关，该计划开发了新的本科和研究生课程，作为明尼苏达大学地理生物学课程的基础。在此项目描述中工作的研究生也将在整个资助期间得到支持和指导。教育和推广计划还通过为学生退伍军人建立夏季研究经验，增加了退伍军人的研究机会，并通过参与美国国家科学基金会资助的北极星STEM联盟，UMN探索工程和物理科学计划的职业生涯，以及促进奇卡诺人和美洲原住民科学协会的年度会议，为高中生和代表性不足的少数民族提供了推广。

Phosphatic mineral deposits are well known for their exquisite preservation of soft tissue ? including fossilized cells. Large septate filaments interpreted as the oldest eukaryotes are preserved in 1.6 billion-year-old phosphorites from the Vindhyan Basin in Central India, and the oldest putative metazoans are preserved as phosphatized symmetrical cell clusters in the 600-milion-year-old Doushantuo Formation in southern China. Interestingly, large vacuolate sulfur-oxidizing bacteria are thought to mediate modern phosphogenesis, and commonly possess morphologies that closely resemble both the Vindhyan filaments and the Doushantuo globular microfossils. Could the Vindhyan or Doushantuo microfossils represent vacuolated sulfur bacteria, rather than eukaryotes? Could these microfossils provide evidence of the ancient mediation of phosphorites by sulfur bacteria? In the case of the Doushantuo microbiota, some microfossils are clearly eukaryotic, and likely metazoan in origin, while others cannot be easily interpreted as animals ? but are the bacterial and animal interpretations mutually exclusive? Other ancient and recent phosphorite deposits also possess structures that might well represent fossilized sulfur bacteria, but criteria for their recognition are not yet established. The PI?s research group will: 1) investigate newly-discovered modern sulfur bacteria that are partially entombed in phosphatic minerals; 2) perform phosphatization experiments with modern sulfur bacteria to investigate the taphonomy of phosphatized bacteria; 3) compare modern phosphatized sulfur bacteria with ancient microfossils from Proterozoic and Phanerozoic phosphorites; and 4) use observations of modern sulfur bacteria to develop new criteria for differentiating fossils of giant sulfur bacteria from those of microbial eukaryotes - including embryonic metazoans.The research component of this proposal is tied closely to an education and outreach plan that develops new undergraduate and graduate courses as the foundation of a geobiology curriculum at the University of Minnesota. A graduate student who will work on the projects describer herein will also be supported and mentored throughout the grant period. The education and outreach plan also increases research opportunities for military veterans through the establishment of a summer research experience for student veterans, as well as providing outreach to high school students and underrepresented minorities through participation in the NSF-funded North Star STEM Alliance, the UMN Exploring Careers in Engineering and Physical Science Program, and the annual meeting of the Society for the Advancement of Chicanos and Native Americans in Sciences.