The tropical marine actinomycete Nocardiopsis dassonvillei NCIM 5124 as novel source of ectoine: Genomic and transcriptomic insights.

Since ectoine is a high-value product, overviewing strategies for identifying novel microbial sources becomes relevant. In the current study, by following a genome mining approach, the ectoine biosynthetic cluster in a tropical marine strain of Nocardiopsis dassonvillei (NCIM 5124) was located and compared with related organisms. Transcriptome analysis of Control and Test samples (with 0 and 5% NaCl, respectively) was carried out to understand salt induced stress response at the molecular level. There were 4950 differentially expressed genes with 25 transcripts being significantly upregulated in Test samples. NaCl induced upregulation of the ectoine biosynthesis cluster and some other genes (stress response, chaperone/Clp protease, cytoplasm, ribonucleoprotein and protein biosynthesis). The production of ectoine as a stress response molecule was experimentally validated via LCMS analysis. The investigation sheds light on the responses exhibited by this actinomycete in coping up with salt stress and provides a foundation for understanding salt induced molecular interactions.

Efficiently manufacturing ectoine via metabolic engineering and protein engineering of L-2,4-diaminobutyrate transaminase.

Ectoine, so-called tetrahydropyrimidine, is an important osmotic adjustment solute and widely applied in cosmetics and protein protectant. Some attempts have been made to improve the ectoine productivity. However, the strains with both high ectoine production capacity and high glucose conversion were still absent so far. Aim to construct a strain for efficiently producing ectoine, ectoine synthetic gene cluster ectABC from Pseudomonas stutzeri was overexpressed in E. coli BL21 (DE3). The ection production was improved by 382 % (ectoine titer increased from 1.73 g/L to 8.33 g/L) after the rational design of rate-limiting enzyme L-2,4-diaminobutyrate transaminase EctBps (protein engineering) combined with the metabolic engineering that focused on the enrichment and conversion of precursors. The final strain YW20 was applied to overproduce ectoine in fed-batch fermentation and yield 68.9 g/L of ectoine with 0.88 g/L/h of space-time yield and the highest glucose conversion reported [34 % (g/g)]. From the fermentation broth, ectoine was purified with 99.7 % purity and 79.8 % yield. This study successfully provided an engineered strain as well as an efficient method for the industrial bio-synthesis and preparation of ectoine.

Extremozymes and compatible solute production potential of halophilic and halotolerant bacteria isolated from crop rhizospheric soils of Southwest Saurashtra Gujarat.

Halophiles are one of the classes of extremophilic microorganisms that can flourish in environments with very high salt concentrations. In this study, fifteen bacterial strains isolated from various crop rhizospheric soils of agricultural fields along the Southwest coastline of Saurashtra, Gujarat, and identified by 16S rRNA gene sequencing as Halomonas pacifica, H. stenophila, H. salifodinae, H. binhaiensis, Oceanobacillus oncorhynchi, and Bacillus paralicheniformis were investigated for their potentiality to produce extremozymes and compatible solute. The isolates showed the production of halophilic protease, cellulase, and chitinase enzymes ranging from 6.90 to 35.38, 0.004-0.042, and 0.097-0.550 U ml-1, respectively. The production of ectoine-compatible solute ranged from 0.01 to 3.17 mg l-1. Furthermore, the investigation of the ectoine-compatible solute production at the molecular level by PCR showed the presence of the ectoine synthase gene responsible for its biosynthesis in the isolates. Besides, it also showed the presence of glycine betaine biosynthetic gene betaine aldehyde dehydrogenase in the isolates. The compatible solute production by these isolates may be linked to their ability to produce extremozymes under saline conditions, which could protect them from salt-induced denaturation, potentially enhancing their stability and activity. This correlation warrants further investigation.

Optimization of methane gas-liquid mass transfer during biogas-based ectoine production in bubble column bioreactors.

Nowadays, the utilization of biogas for energy generation is hindered by the declining production costs of solar and wind power. A shift towards the valorization of biogas into ectoine, a highly valuable bioproduct priced at 1000 €â¸±kg-1, offers a novel approach to fostering a more competitive biogas market while contributing to carbon neutrality. This study evaluated the optimization of CH4 gas-liquid mass transfer in 10 L bubble column bioreactors for CH4 conversion into ectoine and hydroxyectoine using a mixed methanotrophic culture. The influence of the empty bed residence time (EBRTs of 27, 54, and 104 min) at different membrane diffuser pore sizes (0.3 and 0.6 mm) was investigated. Despite achieving CH4 elimination capacities (CH4-ECs) of 10-12 g⸱m-3⸱h-1, an EBRT of 104 min mediated CH4 limitation within the cultivation broth, resulting in a negligible biomass growth. Reducing the EBRT to 54 min entailed CH4-ECs of 21-24 g⸱m-3⸱h-1, concomitant to a significant increase in biomass growth (up to 0.17 g⸱L⸱d-1) and reaching maximum ectoine and hydroxyectoine accumulation of 79 and 13 mg⸱gVSS-1, respectively. Conversely, process operation at an EBRT of 27 min lead to microbial inhibition, resulting in a reduced biomass growth of 0.09 g⸱L⸱d-1 and an ectoine content of 47 mg⸱gVSS-1. While the influence of diffuser pore size was less pronounced compared to EBRT, the optimal process performance was observed with a diffuser pore size of 0.6 mm.

The role of neutrophil extracellular traps in ß-methylamino L-alanine-induced liver injury in mice.

The non-protein amino acid ß-N-methylamino-L-alanine (BMAA), produced by cyanobacteria, has been recognized as a neurotoxin. L-serine as an antagonist of BMAA can effectively alleviate BMAA-induced neurotoxicity. Although BMAA has long been emphasized as a neurotoxin, with the emergence of BMAA detected in a variety of algae in freshwater around the world and its clear biological enrichment effect, it is particularly important to study the non-neurotoxic adverse effects of BMAA. However, there is only limited evidence to support the ability of BMAA to cause oxidative damage in the liver. The exact molecular mechanism of BMAA-induced liver injury is still unclear. The formation of neutrophil extracellular traps (NETs) is a 'double-edged sword' for the organism, excessive formation of NETs is associated with inflammatory diseases of the liver. Our results innovatively confirmed that BMAA was able to cause the formation of NETs in the liver during the liver injury. The possible mechanism may associated with the regulation of ERK/p38 and cGAS/STING signaling pathways. The massive formation of NETs was able to exacerbate the BMAA-induced oxidative stress and release of inflammatory factors in the mice liver. And the removal of NETs could alleviate this injury. This article will bring a new laboratory evidence for BMAA-induced non-neurotoxicity and immunotoxicity.

Computational Investigation of BMAA and Its Carbamate Adducts as Potential GluR2 Modulators.

Beta-N-methylamino-l-alanine (BMAA) is a potential neurotoxic nonprotein amino acid, which can reach the human body through the food chain. When BMAA interacts with bicarbonate in the human body, carbamate adducts are produced, which share a high structural similarity with the neurotransmitter glutamate. It is believed that BMAA and its l-carbamate adducts bind in the glutamate binding site of ionotropic glutamate receptor 2 (GluR2). Chronic exposure to BMAA and its adducts could cause neurological illness such as neurodegenerative diseases. However, the mechanism of BMAA action and its carbamate adducts bound to GluR2 has not yet been elucidated. Here, we investigate the binding modes and the affinity of BMAA and its carbamate adducts to GluR2 in comparison to the natural agonist, glutamate, to understand whether these can act as GluR2 modulators. Initially, we perform molecular dynamics simulations of BMAA and its carbamate adducts bound to GluR2 to examine the stability of the ligands in the S1/S2 ligand-binding core of the receptor. In addition, we utilize alchemical free energy calculations to compute the difference in the free energy of binding of the beta-carbamate adduct of BMAA to GluR2 compared to that of glutamate. Our findings indicate that carbamate adducts of BMAA and glutamate remain stable in the binding site of the GluR2 compared to BMAA. Additionally, alchemical free energy results reveal that glutamate and the beta-carbamate adduct of BMAA have comparable binding affinity to the GluR2. These results provide a rationale that BMAA carbamate adducts may be, in fact, the modulators of GluR2 and not BMAA itself.

Guyparkeria halophila: Novel cell platform for the efficient valorization of carbon dioxide and thiosulfate into ectoine.

Utilizing carbon dioxide (CO2) for valuable chemical production is key to a circular economy. Current processes are costly due to limited microorganism use, low-value products, and the need for affordable energy. This study addresses these challenges by using industrial contaminants like thiosulfate (S2O32-) for CO2 conversion into ectoines. Ectoines, are important ingredients as pharmaceuticals and cosmetics. Here, six microbial genomes were identified as potential candidates to valorize CO2 and S2O32- into ectoine. After laboratory validation at 3 % NaCl, the fastest-growing strain, Guyparkeria halophila, was optimized at 6 %, 9 %, and 15 % NaCl, showing the highest specific ectoine contents (mgEct gbiomass-1) at 15 %. Batch bioreactors, combining optimal conditions, achieved maximum specific ectoine contents of 47 %. These results not only constitute the highest ectoine content so far reported by autotrophs and most of heterotrophs, but also the first proof of a novel valorization platform for CO2 and S2O32-, focused on pharmaceuticals production.

ß-N-methylamino-L-alanine production, photosynthesis and transcriptional expression in a possible mutation strain and a wild strain of Thalassiosira minima.

The neurotoxin ß-N-methylamino-L-alanine (BMAA) produced by marine diatoms has been implicated as an important environmental trigger of neurodegenerative diseases in humans. However, the biosynthesis mechanism of BMAA in marine diatoms is still unknown. In the present study, the strain of diatom Thalassiosira minima almost lost the biosynthesis ability for BMAA after a long-term subculture in our laboratory. The production of BMAA-containing proteins in the mutant strain of T. minima reduced to 18.2 % of that in the wild strain, meanwhile the cell size decreased but pigment content increased in the mutant strain. Take consideration of our previous transcriptional data on the mixed diatom and cyanobacterium cultures, the current transcriptome analysis showed four identical and highly correlated KEGG pathways associated with the accumulation of misfolded proteins in diatom, including ribosome, proteasome, SNARE interactions in vesicle transport, and protein processing in the endoplasmic reticulum. Analysis of amino acids and transcriptional information suggested that amino acid synthesis and degradation are associated with the biosynthesis of BMAA-containing proteins. In addition, a reduction in the precision of ubiquitination-mediated protein hydrolysis and vesicular transport by the COPII system will exacerbate the accumulation of BMAA-containing proteins in diatoms.

Ectoine maintains the flavor and nutritional quality of broccoli during postharvest storage.

The bacterial derived osmolyte ectoine has been shown to stabilize cell structure and function, a property that may help to extend the shelf life of broccoli. The impact of ectoine on broccoli stored for 4 d at 20 °C and 90% relative humidity was investigated. Results indicated that 0.20% ectoine treatment maintained the quality of broccoli, by reducing rate of respiration and ethylene generation, while increasing the levels of total phenolics, flavonoids, TSS, soluble protein, and vitamin C, relative to control. Headspace-gas chromatography-mass spectrometry, transcriptomic and metabolomic analyses revealed that ectoine stabilized aroma components in broccoli by maintaining level of volatile compounds and altered the expression of genes and metabolites associated with sulfur metabolism, as well as fatty acid and amino acid biosynthesis pathways. These findings provide a greater insight into how ectoine preserves the flavor and nutritional quality of broccoli, thus, extending its shelf life.

Genome mining and physiological analyses uncover adaptation strategies and biotechnological potential of Virgibacillus dokdonensis T4.6 isolated from high-salt shrimp paste.

Virgibacillus spp. stand out as a potent starter culture for accelerating the fermention of fish sauces and shrimp pastes. However, the underlying molecular mechanisms responsible for their adaptation and biotechnological potential remain elusive. Therefore, the present study focuses on phenotypic and genomic analyses of a halophilic bacterium Virgibacillus dokdonensis T4.6, derived from Vietnamese high-salt fermented shrimp paste. The draft genome contained 4,096,868 bp with 3780 predicted coding sequences. Genome mining revealed the presence of 143 genes involved in osmotic adaptation explaining its resistant phenotype to 24% (w/v) NaCl. Among them, 37 genes making up the complete ectoine metabolism pathway, confirmed its ability to produce 4.38 ± 0.29 wt% ectoine under 12.5% NaCl stress. A significant finding was the identification of 39 genes responsible for an entire degradation pathway of the toxic biogenic amine histamine, which was in agreement with its histamine degradation rate of 42.7 ± 2.1% in the HA medium containing 5 mM histamine within 10 days at 37 °C. Furthermore, 114 proteolytic and 19 lipolytic genes were detected which might contribute to its survival as well as the nutrient quality and flavor of shrimp paste. Of note, a putative gene vdo2592 was found as a possible novel lipase/esterase due to its unique Glycine-Aspartate-Serine-Leucine (GDSL) sequence motif. This is the first report to reveal the adaptative strategies and related biotechnological potential of Virgibacillus associated with femented foods. Our findings indicated that V. dokdonensis T4.6 is a promising starter culture for the production of fermented shrimp paste products.

Ectoine Enhances Mucin Production Via Restoring IL-13/IFN-γ Balance in a Murine Dry Eye Model.

Purpose: This study aimed to explore protective effects and potential mechanism of ectoine, a natural osmoprotectant, on ocular surface mucin production in dry eye disease. Methods: A dry eye model was established in C57BL/6 mice exposed to desiccating stress (DS) with untreated (UT) mice as controls. DS mice were topically treated with 2.0% ectoine or PBS vehicle. Corneal epithelial defects were assessed by Oregon Green Dextran (OGD) fluorescent staining. Conjunctival goblet cells, ocular mucins, and T help (Th) cytokines were evaluated by immunofluorescent staining or ELISA, and RT-qPCR. Results: Compared with UT mice, corneal epithelial defects were detected as strong punctate OGD fluorescent staining in DS mice with vehicle, whereas ectoine treatment largely reduced OGD staining to near-normal levels. Conjunctival goblet cell density and cell size decreased markedly in DS mice, but was significantly recovered by ectoine treatment. The protein production and mRNA expression of two gel-forming secreted MUC5AC and MUC2, and 4 transmembrane mucins, MUC1, MUC4, MUC16, and MUC15, largely decreased in DS mice, but was restored by ectoine. Furthermore, Th2 cytokine IL-13 was inhibited, whereas Th1 cytokine IFN-γ was stimulated at protein and mRNA levels in conjunctiva and draining cervical lymph nodes (CLNs) of DS mice, leading to decreased IL-13/IFN-γ ratio. Interestingly, 2.0% ectoine reversed their alternations and restored IL-13/IFN-γ balance. Conclusions: Our findings demonstrate that topical ectoine significantly reduces corneal damage, and enhances goblet cell density and mucin production through restoring imbalanced IL-13/IFN-γ signaling in murine dry eye model. This suggests therapeutic potential of natural osmoprotectant ectoine for dry eye disease.

[Advances in ectoine biosynthesis and biochemical characteristics of key enzymes].

Compatible solutes are highly water-soluble organic osmolytes produced by microorganisms to adapt to extreme environments, such as high salinity and osmotic pressure. Among these, ectoine plays a crucial role in repairing and protecting nucleic acids, protein, biofilms, and cells. As a result, it has found widespread applications in cosmetics, biological agents, the enzyme industry, medicine, and other fields. Currently, the market value of ectoine is around US$ 1 000/kg, with a global demand reaching 15 000 tons per year. Although halophilic bacteria serve as the natural source of ectoine synthesis, its production in high-salinity media presents challenges such as equipment corrosion and high cost for industrial production. Advancements in functional genomics, systems biology, and synthetic biology have paved the way for the development of high-yielding cell factories through metabolic engineering, leading to significant progress. For example, engineered Escherichia coli achieved a maximum ectoine titer of 131.8 g/L, with a productivity of 1.37 g/(L·h). This review aims to explore the biosynthetic pathway, biochemical characteristics of key enzymes, and the biosynthesis of ectoine, shedding light on current research status and offering insights for industrial-scale ectoine production.

Rational engineering of Halomonas salifodinae to enhance hydroxyectoine production under lower-salt conditions.

Hydroxyectoine is an important compatible solute that holds potential for development into a high-value chemical with broad applications. However, the traditional high-salt fermentation for hydroxyectoine production presents challenges in treating the high-salt wastewater. Here, we report the rational engineering of Halomonas salifodinae to improve the bioproduction of hydroxyectoine under lower-salt conditions. The comparative transcriptomic analysis suggested that the increased expression of ectD gene encoding ectoine hydroxylase (EctD) and the decreased expressions of genes responsible for tricarboxylic acid (TCA) cycle contributed to the increased hydroxyectoine production in H. salifodinae IM328 grown under high-salt conditions. By blocking the degradation pathway of ectoine and hydroxyectoine, enhancing the expression of ectD, and increasing the supply of 2-oxoglutarate, the engineered H. salifodinae strain HS328-YNP15 (ΔdoeA::PUP119-ectD p-gdh) produced 8.3-fold higher hydroxyectoine production than the wild-type strain and finally achieved a hydroxyectoine titer of 4.9 g/L in fed-batch fermentation without any detailed process optimization. This study shows the potential to integrate hydroxyectoine production into open unsterile fermentation process that operates under low-salinity and high-alkalinity conditions, paving the way for next-generation industrial biotechnology. KEY POINTS: • Hydroxyectoine production in H. salifodinae correlates with the salinity of medium • Transcriptomic analysis reveals the limiting factors for hydroxyectoine production • The engineered strain produced 8.3-fold more hydroxyectoine than the wild type.

High production of ectoine from methane in genetically engineered Methylomicrobium alcaliphilum 20Z by preventing ectoine degradation.

BACKGROUND: Methane is a greenhouse gas with a significant potential to contribute to global warming. The biological conversion of methane to ectoine using methanotrophs represents an environmentally and economically beneficial technology, combining the reduction of methane that would otherwise be combusted and released into the atmosphere with the production of value-added products. RESULTS: In this study, high ectoine production was achieved using genetically engineered Methylomicrobium alcaliphilum 20Z, a methanotrophic ectoine-producing bacterium, by knocking out doeA, which encodes a putative ectoine hydrolase, resulting in complete inhibition of ectoine degradation. Ectoine was confirmed to be degraded by doeA to N-α-acetyl-L-2,4-diaminobutyrate under nitrogen depletion conditions. Optimal copper and nitrogen concentrations enhanced biomass and ectoine production, respectively. Under optimal fed-batch fermentation conditions, ectoine production proportionate with biomass production was achieved, resulting in 1.0 g/L of ectoine with 16 g/L of biomass. Upon applying a hyperosmotic shock after high-cell-density culture, 1.5 g/L of ectoine was obtained without further cell growth from methane. CONCLUSIONS: This study suggests the optimization of a method for the high production of ectoine from methane by preventing ectoine degradation. To our knowledge, the final titer of ectoine obtained by M. alcaliphilum 20ZDP3 was the highest in the ectoine production from methane to date. This is the first study to propose ectoine production from methane applying high cell density culture by preventing ectoine degradation.

Metabolic Engineering of Corynebacterium glutamicum for Highly Efficient Production of Ectoine.

Ectoine is a compatible solute that functions as a cell protector from various stresses, protecting cells and stabilizing biomolecules, and is widely used in medicine, cosmetics, and biotechnology. Microbial fermentation has been widely used for the large-scale production of ectoine, and a number of fermentation strategies have been developed to increase the ectoine yield, reduce production costs, and simplify the production process. Here, Corynebacterium glutamicum was engineered for ectoine production by heterologous expression of the ectoine biosynthesis operon ectBAC gene from Halomonas elongata, and a series of genetic modifications were implemented. This included introducing the de3 gene from Escherichia coli BL21 (DE3) to express the T7 promoter, eliminating the lysine transporter protein lysE to limit lysine production, and performing a targeted mutation lysCS301Y on aspartate kinase to alleviate feedback inhibition of lysine. The new engineered strain Ect10 obtained an ectoine titer of 115.87 g/L in an optimized fed-batch fermentation, representing the highest ectoine production level in C. glutamicum and achieving the efficient production of ectoine in a low-salt environment.

Impact of the neurotoxin ß-N-methylamino-L-alanine on the diatom Thalassiosira pseudonana using metabolomics.

The neurotoxin ß-N-methylamino-L-alanine (BMAA) has emerged as an environmental factor related to neurodegenerative diseases. BMAA is produced by various microorganisms including cyanobacteria and diatoms, in diverse ecosystems. In the diatom Phaeodactylum tricornutum, BMAA is known to inhibit growth. The present study investigated the impact of BMAA on the diatom Thalassiosira pseudonana by exposing it to different concentrations of exogenous BMAA. Metabolomics was predominantly employed to investigate the effect of BMAA on T. pseudonana, and MetaboAnalyst (https://www.metabo-analyst.ca/) was used to identify BMAA-associated metabolisms/pathways in T. pseudonana. Furthermore, to explore the unique response, specific metabolites were compared between treatments. When the growth was obstructed by BMAA, 17 metabolisms/pathways including nitrogen and glutathione (i.e. oxidative stress) metabolisms, were influenced in T. pseudonana. This study has further determined that 11 out of 17 metabolisms/pathways could be essentially affected by BMAA, leading to the inhibition of diatom growth.

Presence of the neurotoxin ß-N-methylamino-L-alanine in irrigation water and accumulation in cereal grains with human exposure risk.

The present study demonstrates the presence of the neurotoxin ß-N-methylamino-L-alanine and its cyanobacterial producers in irrigation water and grains of some cereal plants from farmlands irrigated with Nile River water in Egypt. BMAA detected by LC-MS/MS in phytoplankton samples was found at higher concentrations of free form (0.84-11.4 µg L-1) than of protein-bound form (0.16-1.6 µg L-1), in association with the dominance of cyanobacteria in irrigation water canals. Dominant cyanobacterial species isolated from these irrigation waters including Aphanocapsa planctonica, Chroococcus minutus, Dolichospermum lemmermanni, Nostoc commune, and Oscillatoria tenuis were found to produce different concentrations of free (4.8-71.1 µg g-1 dry weight) and protein-bound (0.1-11.4 µg g-1 dry weight) BMAA. In the meantime, BMAA was also detected in a protein-bound form only in grains of corn (3.87-4.51 µg g-1 fresh weight) and sorghum (5.1-7.1 µg g-1 fresh weight) plants, but not in wheat grains. The amounts of BMAA accumulated in these grains correlated with BMAA concentrations detected in relevant irrigation water canals. The presence of BMAA in cereal grains would constitute a risk to human and animal health upon consumption of contaminated grains. The study, therefore, suggests continuous monitoring of BMAA and other cyanotoxins in irrigation waters and edible plants to protect the public against exposure to such potent toxins.

Ectoine production from a novel bacterial strain and high-purity purification with a cost-effective and single-step method.

This study marks the exploration into the production of ectoine, a valuable compound with significant potential as an antioxidant, osmoprotectant, anti-inflammatory agent, and stabilizer of cell membranes, proteins, and DNA integrity. Our focus centred on investigating the presence of ectoine and optimizing its production by the novel ectoine producer bacterial strain, Piscibacillus halophilus. For the optimization of ectoine production the effects of carbon and nitrogen sources, salt, pH, agitation and incubation period were optimized by one-factor-at-a-time. We started with an initial ectoine content of 46.92 mg/L, and through a series of optimization processes, we achieved a remarkable increase, resulting in an ectoine content of 1498.2 mg/L. The bacterial species P. halophilus achieved its highest ectoine production after 48 h of incubation, with conditions set at 10 % (w/v) salinity, pH of 7.50, and an agitation speed of 160 rpm. These precise conditions were found to be the most favourable for maximizing ectoine production by this strain. Besides, we have achieved successful purification of ectoine from the crude extract through a streamlined single-step process. This purification method has delivered an exceptional level of purity, surpassing 99.15 %, and an impressive yield of over 99 %. Importantly, we accomplished this using readily available and cost-effective strong acids (HCl) and strong bases (NaOH) to arrange pH gradients. The use of acid and base in the purification process of ectoine reflects an innovative and sustainable methodology.

Neuronal control of microglia through the mitochondria.

The microbial toxin ß-N-methylamino-L-alanine (BMAA), which is derived from cyanobacteria, targets neuronal mitochondria, leading to the activation of neuronal innate immunity and, consequently, neurodegeneration. Although known to modulate brain inflammation, the precise role of aberrant microglial function in the neurodegenerative process remains elusive. To determine if neurons signal microglial cells, we treated primary cortical neurons with BMAA and then co-cultured them with the N9 microglial cell line. Our observations indicate that microglial cell activation requires initial neuronal priming. Contrary to what was observed in cortical neurons, BMAA was not able to activate inflammatory pathways in N9 cells. We observed that microglial activation is dependent on mitochondrial dysfunction signaled by BMAA-treated neurons. In this scenario, the NLRP3 pro-inflammatory pathway is activated due to mitochondrial impairment in N9 cells. These results demonstrate that microglia activation in the presence of BMAA is dependent on neuronal signaling. This study provides evidence that neurons may trigger microglia activation and subsequent neuroinflammation. In addition, we demonstrate that microglial activation may have a protective role in ameliorating neuronal innate immune activation, at least in the initial phase. This work challenges the current understanding of neuroinflammation by assigning the primary role to neurons.

Neurotoxic non-protein amino acids in commercially harvested Lobsters (Homarus americanus H. Milne-Edwards).

Cyanobacteria produce neurotoxic non-protein amino acids (NPAAs) that accumulate in ecosystems and food webs. American lobsters (Homarus americanus H. Milne-Edwards) are one of the most valuable seafood industries in Canada with exports valued at > $2 billion. Two previous studies have assessed the occurrence of ß-N-methylamino-L-alanine (BMAA) in a small number of lobster tissues but a complete study has not previously been undertaken. We measured NPAAs in eyeballs, brain, legs, claws, tails, and eggs of 4 lobsters per year for the 2021 and 2022 harvests. Our study included 4 male and 4 female lobsters. We detected BMAA and its isomers, N-(2-aminoethyl)glycine (AEG), 2,4-diaminobutyric acid (DAB) and ß-aminomethyl-L-alanine (BAMA) by a fully validated reverse phase chromatography-tandem mass spectrometry method. We quantified BMAA, DAB, AEG and BAMA in all of the lobster tissues. Our quantification data varied by individual lobster, sex and collection year. Significantly more BMAA was quantified in lobsters harvested in 2021 than 2022. Interestingly, more BAMA was quantified in lobsters harvested in 2022 than 2021. Monitoring of lobster harvests for cyanobacterial neurotoxins when harmful algal bloom events occur could mitigate risks to human health.