Bacteria that successfully adapt to different substrates and environmental niches within the lung and overcome the immune defence can cause serious lung infections. Such infections are generally complex, and recognized as polymicrobial in nature. Both Pseudomonas aeruginosa and Streptococcus pneumoniae can cause chronic lung infections and were both detected in cystic fibrosis (CF) lung at different stages. In this study, single and dual species cultures of Pseudomonas aeruginosa and Streptococcus pneumoniae were studied under well-controlled planktonic growth conditions. Under pH-controlled conditions, both species apparently benefited from the presence of the other. In co-culture with P. aeruginosa, S. pneumoniae grew efficiently under aerobic conditions, whereas in pure S. pneumoniae culture, growth inhibition occurred in bioreactors with dissolved oxygen concentrations above the microaerobic range. Lactic acid and acetoin that are produced by S. pneumoniae were efficiently utilized by P. aeruginosa. In pH-uncontrolled co-cultures, the low pH triggered by S. pneumoniae assimilation of glucose and lactic acid production negatively affected the growth of both strains. Nevertheless, ammonia production improved significantly, and P. aeruginosa growth dominated at later growth stages. This study revealed unreported metabolic interactions of two important pathogenic microorganisms and shed new lights into pathophysiology of bacterial lung infection.

中文翻译：

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肺部居民肺炎链球菌和铜绿假单胞菌的食物网和代谢相互作用

成功适应肺内不同底物和环境生态位并克服免疫防御的细菌可导致严重的肺部感染。这种感染通常是复杂的，并且在本质上被认为是多种微生物。铜绿假单胞菌和肺炎链球菌均可引起慢性肺部感染，并且均在不同阶段的囊性纤维化 (CF) 肺中检测到。在这项研究中，在良好控制的浮游生长条件下研究了铜绿假单胞菌和肺炎链球菌的单菌种和双菌种培养物。在 pH 值控制的条件下，这两个物种显然都受益于另一个物种的存在。与P共培养。绿脓杆菌_ _ _ 肺炎链球菌在有氧条件下有效生长，而在纯S . 肺炎链球菌培养，生长抑制发生在溶解氧浓度高于微需氧范围的生物反应器中。S产生的乳酸和乙偶姻。P有效地利用了肺炎杆菌。绿脓杆菌。在 pH 值不受控制的共培养中，由S引发的低 pH 值。肺炎链球菌同化葡萄糖和乳酸的产生对这两种菌株的生长产生了负面影响。尽管如此，氨产量显着提高，P. 绿脓杆菌的生长在后期生长阶段占主导地位。这项研究揭示了两种重要病原微生物未报道的代谢相互作用，并为细菌性肺部感染的病理生理学提供了新的线索。