iProXProteomicsBing HuDietzia Sp. Dq12-45-1bPseudomonas Stutzerihttp://www.iprox.org/page/project.html?id=IPX0001915000binghu319@bit.edu.cnBeijing Institute of TechnologyiProXBiodegradation of alkanes by microbial communities is ubiquitous in nature. Interestingly, the microbial communities with high hydrocarbon-degrading performances are sometimes composed of not only hydrocarbon degraders but also nonconsumers, but the synergistic mechanisms remain unknown. Here, we found that two bacterial strains isolated from Chinese oil fields, <i>Dietzia</i> sp. strain DQ12-45-1b and <i>Pseudomonas stutzeri</i> SLG510A3-8, had a synergistic effect on hexadecane (C₁₆ compound) biodegradation, even though <i>P. stutzeri</i> could not utilize C₁₆ individually. To gain a better understanding of the roles of the alkane nonconsumer <i>P. stutzeri</i> in the C₁₆-degrading consortium, we reconstructed a two-species stoichiometric metabolic model, <i>i</i>BH1908, and integrated <i>in silico</i> prediction with the following <i>in vitro</i> validation, a comparative proteomics analysis, and extracellular metabolomic detection. Metabolic interactions between <i>P. stutzeri</i> and <i>Dietzia</i> sp. were successfully revealed to have importance in efficient C₁₆ degradation. In the process, <i>P. stutzeri</i> survived on C₁₆ metabolic intermediates from <i>Dietzia</i> sp., including hexadecanoate, 3-hydroxybutanoate, and α-ketoglutarate. In return, <i>P. stutzeri</i> reorganized its metabolic flux distribution to fed back acetate and glutamate to <i>Dietzia</i> sp. to enhance its C₁₆ degradation efficiency by improving <i>Dietzia</i> cell accumulation and by regulating the expression of <i>Dietzia</i> succinate dehydrogenase. By using the synergistic microbial consortium of <i>Dietzia</i> sp. and <i>P. stutzeri</i> with the addition of the <i>in silico</i>-predicted key exchanged metabolites, diesel oil was effectively disposed of in 15 days with a removal fraction of 85.54% ± 6.42%, leaving small amounts of C₁₅ to C₂₀ isomers. Our finding provides a novel microbial assembling mode for efficient bioremediation or chemical production in the future.<b>IMPORTANCE</b> Many natural and synthetic microbial communities are composed of not only species whose biological properties are consistent with their corresponding communities but also ones whose chemophysical characteristics do not directly contribute to the performance of their communities. Even though the latter species are often essential to the microbial communities, their roles are unclear. Here, by investigation of an artificial two-member microbial consortium in <i>n</i>-alkane biodegradation, we showed that the microbial member without the <i>n</i>-alkane-degrading capability had a cross-feeding interaction with and metabolic regulation to the leading member for the synergistic <i>n</i>-alkane biodegradation. Our study improves the current understanding of microbial interactions. Because "assistant" microbes showed importance in communities in addition to the functional microbes, our findings also suggest a useful "assistant-microbe" principle in the design of microbial communities for either bioremediation or chemical production.Metabolic Exchange with Non-Alkane-Consuming Pseudomonas stutzeri SLG510A3-8 Improves <i>n</i>-Alkane Biodegradation by the Alkane Degrader <i>Dietzia</i> sp. Strain DQ12-45-1b.Hu Bing B, Wang Miaoxiao M, Geng Shuang S, Wen Liqun L, Wu Mengdi M, Nie Yong Y, Tang Yue-Qin YQ, Wu Xiao-Lei XLfalseLabel-free proteomics of two bacterial strains grown on hydrocarbonTwo bacterial strains isolated from Chinese oilfield, Dietzia sp. DQ12-45-1b and P. stutzeri SLG510A3-8, were found having synergistic effect on hydrocarbon biodegradation. To investigate the synergy mechanism between the two strains, they were cultivated separately or individually in a two-chamber bioreactor containing the mineral medium supplemented with hexadecane, and were harvested at the later exponential phase for the label-free proteomics analysis on LC-LTQ-Orbitrap MS. Therefore, four groups of proteome profiles were obtained, including the one from Dietzia sp. monoculture, the one from P. stutzeri monoculture, the one from Dietzia sp. in the co-culture system, and the one from P. stutzeri in the co-culture system. The comparative proteomics analysis between the mono- and co-cultivated Dietzia sp. showed that a total of 222 Dietzia sp. proteins had significantly differential expression in the two groups. For P. stutzeri, it was statistically found that a total of 198 P. stutzeri proteins in P. stutzeri mono- and co-culture systems had significantly differential expression. Afterward, by integrating the proteomics data with our in silico data, the synergistic hexadecane degradation was found to be attributed to the cross-feeding and intermediate-induced metabolic regulation between the two strains.Sun Dec 15 00:00:00 GMT 2019PXD01675491280131632033953