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Subpopulation behaviors in lactose metabolism by Streptococcus mutans
Molecular Microbiology ( IF 2.6 ) Pub Date : 2020-09-02 , DOI: 10.1111/mmi.14596
Lin Zeng 1 , Robert A Burne 1
Affiliation  

When Streptococcus mutans is transferred from a preferred carbohydrate (glucose or fructose) to lactose, initiation of growth can take several hours, and substantial amounts of glucose are released during growth. Here, S. mutans strains UA159 and GS‐5 were examined for stochastic behaviors in transcription of the lac operon. Using a gfp reporter fusion, we demonstrated that induction of the lac operon occurs in only a fraction of the population, with prior exposure to carbohydrate source and strain influencing the magniture of the sub‐population response. Lower glucokinase activity in GS‐5 was associated with release of substantially more glucose than UA159 and significantly lower lac expression. Mutants unable to use lactose grew on lactose as the sole carbohydrate when strains with an intact lac operon were also present in the cultures, indicative of the potential for population cheating. Utilizing a set of engineered obligate cheating and non‐cheating strains, we confirmed that cheating can sustain a heterogeneous population. Futher, obligate cheaters of GS‐5 competed well with the non‐cheaters and showed a high degree of competitive fitness in a human‐derived consortium biofilm model. The results show that bet‐hedging behaviors in carbohydrate metabolism may substantially influence the composition and pathogenic potential of oral biofilms.

中文翻译:

变形链球菌在乳糖代谢中的亚群行为

变形链球菌从首选碳水化合物(葡萄糖或果糖)转移到乳糖时,开始生长可能需要几个小时,并且在生长过程中会释放大量葡萄糖。在这里,研究了变形链球菌菌株 UA159 和 GS-5 在lac操纵子转录中的随机行为。使用gfp报告基因融合,我们证明lac操纵子的诱导仅发生在一小部分人群中,事先接触碳水化合物来源和菌株会影响亚群反应的幅度。GS-5 中较低的葡萄糖激酶活性与释放比 UA159 多得多的葡萄糖和显着降低lac 相关表达。当培养物中也存在具有完整lac操纵子的菌株时,无法使用乳糖的突变体以乳糖作为唯一的碳水化合物生长,这表明存在人口作弊的可能性。利用一组经过设计的专性作弊和非作弊菌株,我们证实作弊可以维持异质人口。此外,GS-5 的专性作弊者与非作弊者竞争良好,并在人类衍生的财团生物膜模型中表现出高度的竞争适应性。结果表明,碳水化合物代谢中的对冲行为可能会显着影响口腔生物膜的组成和致病潜力。
更新日期:2020-09-02
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