A chemically-defined growth medium to support Lactobacillus-Acetobacter community analysis

Abstract

Lactobacilli and acetobacters are commercially important bacteria that often form communities in natural fermentations, including food preparations, spoilage, and in the digestive tract of Drosophila melanogaster fruit flies. Communities of these bacteria are widespread and prolific, despite numerous strain-specific auxotrophies, suggesting they have evolved nutrient interdependencies that regulate their growths. The use of a chemically-defined medium (CDM) supporting the growth of both groups of bacteria would greatly facilitate identification of the precise metabolic interactions between these two groups of bacteria. While numerous such media have been developed that support specific strains of lactobacilli and acetobacters, there has not been a medium formulated to support both genera. We developed such a medium, based on a previous Lactobacillus CDM, by modifying the nutrient abundances to improve growth of both groups of bacteria. We further simplified the medium by substituting casamino acids for individual amino acids and the standard Wolfe's vitamins and mineral stocks for individual vitamins and minerals, resulting in a reduction from 40 to 8 stock solutions. The new CDM and variations of it support robust growth of lactobacilli and acetobacters. We provide the composition and an example of its use to measure nutritional interactions.

Extracellular electron transfer increases fermentation in lactic acid bacteria via a hybrid metabolism

“…Bacterial strains were incubated without shaking except for E. coli (250 RPM) and at either 30 or 37 °C. Where indicated, strains were grown in filter-sterilized MRS ( De MAN et al, 1960 ) lacking beef extract with either 110 mM glucose [gMRS] or 110 mM mannitol [mMRS], or a chemically defined minimal medium ( Supplementary file 4 ) with 125 mM glucose [gCDM] or 125 mM mannitol [mCDM] for 18 hr ( Aumiller et al, 2021 ). Riboflavin (1 mg/L) was routinely added to the CDM.…”

Discovery of extracellular electron uptake by the lactic acid bacterium Lactiplantibacillus plantarum

“…To promote growth without usurping the role of the cathode as the electron donor, we supplied 5 mM glucose as a carbon source, since this concentration of glucose can only marginally be used as electron donor for L. plantarum 24 . After culturing L. plantarum cells in a minimal medium 25 (Supplementary Table 1) in bioelectrochemical reactors, we poised the cathode polarized at different potentials (-0.15, -0.25, -0.40 and − 0.60 V vs Ag/AgCl KCl sat . ), added nitrate, and monitored current at the cathode (Supplementary Fig.…”

“…When L. plantarum wild type EET activity versus the mutants was compared, cells were grown as described and the number of cells was normalized across the strains prior to its inoculation in the electrochemical cells. For growing the strains in the bioelectrochemical reactors we used a Chemically De ned Media (CDM) 25 (see composition in Supplementary Information) containing 5 mM of glucose and 10 mM of nitrate. The media was adjusted to pH 6.5 and then lter sterilized.…”

Nitrogen source: an effective component for the growth and viability of Lactobacillus delbrueckii subsp. bulgaricus

“…Impact of L-histidine supplementation on the growth of S9 Lb. bulgaricus strain Supplementing the growth media KCMax (5/10), KCMax (10/5), and KCMax (10/10) with varying L-histidine concentrations (4 g/l or 0.4% and 0.5 g/l or 0.005%) impacted cell growth during fermentation (Aumiller et al, 2021). The bacterial count for the buffered MRS and the KCMax blends (0.4% and 0.005% L-histidine) elucidated its impact on strain viability.…”