Mechanism of high d-aspartate production in the lactic acid bacterium Latilactobacillus sp. strain WDN19
Mechanism of high d-aspartate production in the lactic acid bacterium Latilactobacillus sp. strain WDN19
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DOI：
10.1007/s00253-022-11870-w
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发表时间：
2022-03
影响因子：
5
通讯作者：
Kengo Kajitani;T. Ishikawa;Tomohiro Kobayashi;Miharu Asato;K. Shibata;Tomoaki Kouya;Shouji Takahashi-Shouji-T
中科院分区：
文献类型：
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作者：
Kengo Kajitani;T. Ishikawa;Tomohiro Kobayashi;Miharu Asato;K. Shibata;Tomoaki Kouya;Shouji Takahashi-Shouji-T
D-天冬氨酸(d-Asp)是一种有用的半合成抗生素化合物，对人类有潜在的有益影响。几种乳酸菌(LAB)产生-天冬氨酸，作为细胞壁肽聚糖的一种成分。我们之前分离到一株能够胞外大量产生d-Asp的实验室菌株(命名为WDN19)。在这里，我们展示了影响高天冬氨酸生产能力的因素。菌株WDN19与弯曲乳杆菌的亲缘关系最近，其富含天冬氨酸的能力是OFL的13.7倍。曲率DSM 20019。天冬氨酸外消旋酶(RacD)催化底物中的天冬氨酸合成d-天冬氨酸。在培养过程中，菌株WDN19的racD活性高于菌株Dsm 20019，尤其是在生长的早期，由于菌株WDN19具有更高的racD转录水平和更高的racD活性。在合成培养基中，菌株WDN19能产生D，L-天冬氨酸，而菌株DSM-20019则没有。在WDN19和DSM 20019菌株中分别加入L-天冬酰胺(L-天冬酰胺)，使L-天冬氨酸的产量分别增加和增加，提示L-天冬氨酸合成天冬酰胺酶。两株菌株对L-天冬氨酸的吸收能力相似，但在生长指数中期、生长稳定期早期和胞内L-天冬氨酸的活性明显高于WDN19。在它们的基因组序列中，除racD外，只有天冬氨酸氨基转移酶基因在L-Asp代谢酶中被发现，但在WDN19菌株中被转座子插入而被破坏。这些观察结果表明，菌株WDN19的高天冬氨酸氨基转移酶(RacD)和抗天冬氨酸氨基转移酶(ANSA)活性以及1-天冬氨酸(L-Asp)的供应能力是其高产的主要基础。
d-Aspartate (d-Asp) is a useful compound for a semisynthetic antibiotic and has potentially beneficial effects on humans. Several lactic acid bacteria (LAB) species produced-Asp as a component of cell wall peptidoglycan. We previously isolated a LAB strain (named strain WDN19) that can extracellularly produce a large amount ofd-Asp. Here, we show the factors that contribute to highd-Asp production ability. Strain WDN19 was most closely related toLatilactobacillus curvatus.Thed-Asp production ability of strain WDN19 in a rich medium was 13.7-fold higher than that ofL. curvatusDSM 20019. A major part ofd-Asp was synthesized froml-Asp contained in the medium by aspartate racemase (RacD). During their cultivation, the RacD activity in strain WDN19 was higher than in strain DSM 20019, especially much higher in the early exponential growth phase because of the higherracDtranscription and the higher activity of RacD itself of strain WDN19. In a synthetic medium, the extracellular production ofd,l-Asp was observed in strain WDN19 but not in strain DSM 20019. The addition ofl-asparagine (l-Asn) to the medium increased and gaved,l-Asp production in strains WDN19 and DSM 20019, respectively, suggestingl-Asp synthesis byl-asparaginase (AsnA). Thel-Asn uptake ability of the strains was similar, but the AsnA activity in the middle exponential and early stationary growth phases and intracellulard,l-Asp was much higher in strain WDN19. In their genome sequences, only an aspartate aminotransferase gene was found amongl-Asp-metabolizing enzymes, except for RacD, but was disrupted in strain WDN19 by transposon insertion. These observations indicated that the highd-Asp production ability of strain WDN19 was mainly based on high RacD and AnsA activities andl-Asp supply.Key points•Strain WDN19 was suggested to be a strain of Latilactobacillus curvatus.•Extracellular highd-Asp production ability was not a common feature of L. curvatus.•Highd-Asp production was due to high RacD and AnsA activities andl-Asp supply.