title: 2,3-Butanediol fermentation promotes growth of Serratia plymuthica at low pH but not survival of extreme acid challenge.
abstract: The mechanisms by which Enterobacteriaceae can survive or grow at low pH are of interest because members of this family are increasingly linked to problems of spoilage and foodborne infection related to mildly acidic foods. In this work, we investigated the contribution of the 2,3-butanediol fermentation pathway in coping with specific forms of acid stress in Serratia plymuthica RVH1. This pathway consumes intracellular protons, similar to the amino acid decarboxylases which are involved in acid resistance in Enterobacteriaceae. While its role in preventing excessive acidification in media with an initial neutral pH but containing fermentable sugars has been established, we here addressed the question whether it supports survival of severe acid challenge (pH2.5-3.5) and/or enhances the ability to initiate growth at moderately low pH (pH4.0-5.0) in acidified LB medium and in tomato juice. Using a budAB::cat mutant, deficient in 2,3-butanediol fermentation, we showed that the pathway did not influence survival in simulated gastric fluid and is not involved in the acid tolerance response (ATR) in S. plymuthica RVH1. On the other hand, the pathway promoted growth at moderately low pH. In acidified LB medium, the mutant stopped growing at a lower final cell density than the wild-type strain. In tomato juice, additionally, the minimal pH at which the mutant could grow (pH4.20-4.30) was increased compared to that of the wild-type (pH4.10). Growth of the wild-type strain was often accompanied by a pH increase, in contrast to the budAB::cat mutant, where the opposite was observed. However, the differences in growth between the wild-type and budAB::cat mutant could not only be explained by external pH, suggesting that the 2,3-butanediol fermentation contributed to intracellular pH homeostasis. Based on these data, we propose the contribution to growth at low pH as a novel biological function of 2,3-butanediol fermentation in Enterobacteriaceae.
authors: Laboratory of Food Microbiology, KU Leuven, Kasteelpark Arenberg 22, 3001 Leuven, Belgium; Leuven Food Science and Nutrition Research Centre (LFoRCe), KU Leuven, Kasteelpark Arenberg 22, 3001 Leuven, Belgium; Department of Microbial and Molecular Systems (M(2)S), Faculty of Bioscience Engineering, KU Leuven, Kasteelpark Arenberg 22, 3001 Leuven, Belgium.
authors: Bram
authors: B
authors: Vivijs
authors: Laboratory of Food Microbiology, KU Leuven, Kasteelpark Arenberg 22, 3001 Leuven, Belgium; Leuven Food Science and Nutrition Research Centre (LFoRCe), KU Leuven, Kasteelpark Arenberg 22, 3001 Leuven, Belgium; Department of Microbial and Molecular Systems (M(2)S), Faculty of Bioscience Engineering, KU Leuven, Kasteelpark Arenberg 22, 3001 Leuven, Belgium.
authors: Pieter
authors: P
authors: Moons
authors: Leuven Food Science and Nutrition Research Centre (LFoRCe), KU Leuven, Kasteelpark Arenberg 22, 3001 Leuven, Belgium; Division of Mechatronics, Biostatistics and Sensors (MeBioS), KU Leuven, Willem de Croylaan 42, 3001 Leuven, Belgium; Department of Biosystems (BIOSYST), Faculty of Bioscience Engineering, KU Leuven, Willem de Croylaan 42, 3001 Leuven, Belgium.
authors: Annemie H
authors: AH
authors: Geeraerd
authors: Laboratory of Food Microbiology, KU Leuven, Kasteelpark Arenberg 22, 3001 Leuven, Belgium; Leuven Food Science and Nutrition Research Centre (LFoRCe), KU Leuven, Kasteelpark Arenberg 22, 3001 Leuven, Belgium; Department of Microbial and Molecular Systems (M(2)S), Faculty of Bioscience Engineering, KU Leuven, Kasteelpark Arenberg 22, 3001 Leuven, Belgium.
authors: Abram
authors: A
authors: Aertsen
authors: Laboratory of Food Microbiology, KU Leuven, Kasteelpark Arenberg 22, 3001 Leuven, Belgium; Leuven Food Science and Nutrition Research Centre (LFoRCe), KU Leuven, Kasteelpark Arenberg 22, 3001 Leuven, Belgium; Department of Microbial and Molecular Systems (M(2)S), Faculty of Bioscience Engineering, KU Leuven, Kasteelpark Arenberg 22, 3001 Leuven, Belgium. Electronic address: Chris.Michiels@biw.kuleuven.be.
authors: Chris W
authors: CW
authors: Michiels
mesh_terms: D000143:Acids / Q000494:pharmacology; D000818:Animals; D002072:Butylene Glycols / Q000494:pharmacology*; D005516:Food Microbiology; D006863:Hydrogen-Ion Concentration; D018551:Solanum lycopersicum / Q000382:microbiology; D050296:Microbial Viability / Q000187:drug effects; D009154:Mutation; D012705:Serratia / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism
chemical_list: D000143:Acids; D002072:Butylene Glycols; C026978:2,3-butylene glycol
keywords: 2,3-Butanediol fermentation; Acid stress; Low pH growth; Tomato juice