Differences in Glutamate Decarboxylases between Lactobacillus Strains/Species

Papers broadly covering the Amanita genus.
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Differences in Glutamate Decarboxylases between Lactobacillus Strains/Species

Post by lostmushroomforest » Tue Oct 26, 2021 6:37 pm

Thought I would share this paper, which talks about the ideal temperature / pH ranges for isolated glutamate decarboxylases produced by different Lactobacilli species:

Characterization of Glutamate Decarboxylase from a High γ-Aminobutyric Acid (GABA)-Producer, Lactobacillus paracasei
https://www.tandfonline.com/doi/pdf/10.1271/bbb.70163

Not only do different glutamate decarboxylases have different ideal pH / temperature ranges for decarboxylation, they also have different levels of efficacy in converting glutamate to GABA. This means that different Lactobacillus are better at converting ibotenic acid to muscimol. This paper goes into more detail comparing the GABA production between more Lactobacillus strains/species:

Enhanced production of γ-aminobutyric acid (GABA) using Lactobacillus plantarum EJ2014 with simple medium composition
https://www.sciencedirect.com/science/a ... 3820314316

There is an incredible amount of variance in procedure between the experiments compared in the meta-analysis of Table 1 of this paper, so it is difficult to fully compare the different decarboxylation potential of strains/species. Unfortunately, the paper only tests the effects of different pHs and glucose / MSG / yeast nutrient concentrations on decarboxylation of glutamate by Lactobacillus Plantarum. However, I think it is possible to make several conclusions from these papers:

1) Full decarb using isolated enzymes does not mean full decarb using bacteria that have those enzymes.

2) Lactobacillus Plantarum , the species used in the Trent Austin Patent, is one of the less effective Lactobacillus species for decarboxylating glutamate to GABA (and ibotenic acid to muscimol). This means using more effective isolated Lactobacillus strains with modified versions of the Trent Austin Patent procedure could result in higher levels of decarb. The experimental procedures used in the second paper to optimize the decarboxylation of glutamate by Lactobacillus Plantarum could also be used to optimize the procedure of the Trent Austin Patent for different species of Lactobacillus.

3) Lactobacillus Acidophilus , found in raw milk and yogurt cultures, produce the highest concentrations of GABA from glutamate by a significant margin - which explains why the SOMA (Amanita yogurt) method is so quick and effective. Lactobacillus Brevis also produces high concentrations of GABA from glutamate, significantly more than Lactobacillus Plantarum and is also found in many yogurt cultures. Although Lactobacillus Paracasei's glutamate decarboxylase is more effective than Lactobacillus Brevis, its ideal temperature range [50C, 122F] makes it less useful for decarboxylation than Lactobacillus Brevis [30C, 86F].

This combined with their easy availability makes L. Brevis and L. Acidophilus the best candidates for a modified version of the Trent Austin Patent procedure and supplementing the microbial population of other Amanita ferments.

4) The speed and percentage of decarboxylation of ibotenic acid in non-yogurt based Amanita ferments is highly dependent on the strain/species of lactobacillus present in the microbial culture and the pH of the ferment. For longer ferments like SOMABUCHA (Amanita kombucha), it may take days or weeks to reach the appropriate level of acidity for decarb, depending on the Lactobacillus species/strains present and starting pH. Supplementation with Lactobacillus species/strains that have more effective glutamate decarboxylases and will thrive in the fermentation environment could improve speed/percentage of decarboxylation.
Last edited by lostmushroomforest on Sun Nov 21, 2021 6:54 pm, edited 2 times in total.

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Re: Differences in Glutamate Decarboxylases between Lactobacillus Strains/Species

Post by lostmushroomforest » Wed Oct 27, 2021 4:52 am

Here is one of the articles referenced from the meta-analysis in Table 1 from the second paper. The researchers compare the GABA production / decarboxylation potential of several Lactobacillus strains / species with a strain of Lactobacillus Acidophilus isolated from raw milk and find it to be the most effective out of all them (see page 3, Table 2)

Physiological Characteristics and GABA Production of Lactobacillus acidophilus RMK567 Isolated from Raw Milk
http://koreascience.or.kr/article/JAKO2 ... 053507.pdf

So it looks like the ideal decarb temp for Lactobacillus Acidophilus is 40C / 104F, which offers more detail as to why the raw milk / yogurt decarb methods work so well. However, it makes it less useful for SOMABUCHA fermentations, so I think Lactobacillus Brevis may be the best option since the decarb temps for both these bacteria line up with their ideal temperature for bacterial growth.
Last edited by lostmushroomforest on Thu Oct 28, 2021 2:49 am, edited 1 time in total.

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Re: Differences in Glutamate Decarboxylases between Lactobacillus Strains/Species

Post by lostmushroomforest » Wed Oct 27, 2021 5:13 am

Characterization of a Potential Probiotic Lactobacillus brevis RK03 and Efficient Production of γ-Aminobutyric Acid in Batch Fermentation
https://www.researchgate.net/publicatio ... rmentation

This paper gives us some interesting info on page 2 about differing optimal pH for GABA production between strains of <i>L. brevis</i>.
For example, the highest GABA production was achieved by L. brevis at initial pH 5.0 [15]. A similar optimal pH was found for L. paracasei NFRI 7415 when cells were incubated in medium supplemented with 500 mM monosodium glutamate (MSG) [21]. Additionally, in Streptococcus salivarius subsp.thermophilus Y2, fermentation condition optimization yielded a pH of 4.5 [24]. L. brevis GABA100,isolated from fermenting black raspberry juice, produced maximum GABA levels at pH 3.5 [25].Therefore, the optimum conditions of fermenting microorganisms vary according to the different properties of GADs, with optimal pH ranging from pH 3.5–5.0.
The RK03 strain offers an impressive decarb rate of 93% after 88h. I wish I could compare it to the Lactobacillus Plantarum strain in Trent Austin Patent, but unfortunately, they did not even test the level of decarboxylation from L. Plantarum - they only tested the control, the sample treated with isolated glutamate decarboxylase, and the sample treated with HCl. I suspect this may be because the conversion rate was lower than they expected.
Last edited by lostmushroomforest on Sun Nov 21, 2021 6:54 pm, edited 9 times in total.

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Re: Differences in Glutamate Decarboxylases between Lactobacillus Strains/Species

Post by lostmushroomforest » Wed Oct 27, 2021 1:17 pm

Unfortunately Lactobacillus LB-35, the most commercially available strain of L. Brevis, does not offer the same level of decarb despite having the genes for glutamate decarboxylase:

Transcriptomics reveal different metabolic strategies for acid resistance and gamma-aminobutyric acid (GABA) production in select Levilactobacillus brevis strains
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2996345/

So if supplementing with commercially available L. Brevis is not an option, it makes me curious if juicing + fermenting wild fruits/vegetables until acidified and then using that liquid to augment a SOMABUCHA culture could increase levels of decarb. A lot of these really strong GABA producing strains come from wild ferments, so it may be worth pursuing.

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