5-Aminolevulinic acid: production by fermentation, and agricultural and biomedical applications

Targeted regulation of 5-aminolevulinic acid enhances flavonoids, anthocyanins and proanthocyanidins accumulation in Vitis davidii callus

BACKGROUND

Spine grape (Vitis davidii) is a promising source of high-quality anthocyanins, with vast potential for application in food, pharmaceutical, and cosmetic industries. However, their availability is limited by resource constraints. Plant cell culture has emerged as a valuable approach for anthocyanin production and serves as an ideal model to investigate the regulation of anthocyanin biosynthesis. Elicitors are employed to achieve targeted enhancement of anthocyanin biosynthesis. The present study investigated the impact of 5-aminolevulinic acid (ALA) as an elicitor on the accumulation of anthocyanins and flavonoids during spine grape callus growth. Specifically, we examined the effects of ALA on anthocyanin and its component accumulation in callus, and biosynthetic anthocyanin gene expression.

RESULTS

ALA at 25 µg/L increased the biomass of spine grape callus. ALA induction enhanced the levels of flavonoids, anthocyanins and proanthocyanidins in callus, with maximum values reaching 911.11 mg/100 g DW, 604.60 mg/100 g DW, and 5357.00 mg/100 g DW, respectively, after callus culture for 45 days. Notably, those levels were 1.47-, 1.93- and 1.83-fold higher than controls. ALA induction modulated the flavonoid profile, and among 97 differential flavonoid metabolites differing from controls, 77 were upregulated and 20 were downregulated. Six kinds of anthocyanins, namely cyanidin (8), delphinidin (6), peonidin (5), malvidin (4), petunidin (3) and pelargonidin (3), were detected in callus, with peonidin most abundant. Compared with controls, anthocyanin components were increased in ALA-treated callus. The key genes PAL1, PAL2, PAL4, CHI, CHS3, F3'H, F3H, FLS, DFR, UFGT, MYBA1, LDOX, OMT3, GT1 and ACT involved in anthocyanin biosynthesis were upregulated following ALA treatment, resulting in anthocyanin accumulation.

CONCLUSION

This study revealed a novel mode of ALA-mediated promotion of plant anthocyanin biosynthesis and accumulation at the cellular level, and a strategy for enhancing anthocyanin content in spine grape callus. The findings advance commercial-scale production of anthocyanins via spine grape callus culture. we also explored the accumulation patterns of flavonoids and anthocyanins under ALA treatment. Augmentation of anthocyanins coincided with elevated expression levels of most genes involved in anthocyanin biosynthesis within spine grape callus following ALA treatment.

A Non-functional γ-Aminobutyric Acid Shunt Pathway in Cyanobacterium Synechocystis sp. PCC 6803 Enhances δ-Aminolevulinic Acid Accumulation under Modified Nutrient Conditions

To redirect carbon flux from the γ-aminobutyric acid (GABA) shunt to the δ-aminolevulinic acid (ALA) biosynthetic pathway, we disrupted the GABA shunt route of the model cyanobacterium Synechocystis sp. PCC 6803 by inactivating Gdc, the gene-encoding glutamate decarboxylase. The generated ΔGdc strain exhibited lower intracellular GABA and higher ALA levels than the wild-type (WT) one. The ΔGdc strain’s ALA levels were ~2.8 times higher than those of the WT one when grown with levulinic acid (LA), a competitive inhibitor of porphobilinogen synthase. Abiotic stress conditions including salinity induced by 10 mM NaCl and cold at 4 °C increased the ALA levels in ΔGdc up to ~2.5 and 5 ng g−1 cell DW, respectively. The highest ALA production in the ΔGdc cyanobacteria grown in BG11 medium was triggered by glucose induction, followed by glutamate supplementation with 60 mM of LA, thereby resulting in ~360 ng g−1 cell DW of ALA, that is >300-fold higher ALA accumulation than that observed in ΔGdc cyanobacteria grown in normal medium. Increased levels of the gdhA (involved in the interconversion of α-ketoglutarate to glutamate) and the hemA (a major regulatory target of the ALA biosynthetic pathway) transcripts occurred in ΔGdc cyanobacteria grown under modified growth conditions. Our study provides critical insight into the facilitation of ALA production in cyanobacteria.

Effects of 5-aminolevulinic acid supplementation on milk production, iron status, and immune response of dairy cows

The objective of this study was to investigate the effect of 5-aminolevulinic acid (5-ALA) as a dietary supplement on milk yield and composition as well as iron status and immune response in lactating dairy cows. In this study 13 lactating Holstein cows were randomly assigned to either a control group or a treatment group supplemented with 10 mg of 5-ALA per kilogram of dry matter. During feeding, 5-ALA was mixed with a small amount of the total mixed ration and top-dressed. The experiments followed a crossover design with 2 periods. Each period consisted of an adaptation period of 12 d and a test period of 2 d. Dairy cows fed the diet supplemented with 5-ALA exhibited increased counts of white blood cells and granulocytes compared with the control group. The rate of phagocytosis and mitogen-induced proliferation of peripheral blood mononuclear cells in cows fed 5-ALA were higher than in cows fed a basal diet. However, 5-ALA did not affect iron status or plasma biochemical composition. Supplementation with 5-ALA improved milk protein and milk casein contents; however, it had no effect on milk production, milk fat, lactose, total solids, or solids-not-fat, compared with the control. We conclude that dietary supplementation of 5-ALA to lactating dairy cows may have a positive effect on milk protein synthesis and the immune response.

Metabolic engineering of Escherichia coli for de novo biosynthesis of vitamin B12

The only known source of vitamin B₁₂ (adenosylcobalamin) is from bacteria and archaea. Here, using genetic and metabolic engineering, we generate an Escherichia coli strain that produces vitamin B₁₂ via an engineered de novo aerobic biosynthetic pathway. In vitro and/or in vivo analysis of genes involved in adenosylcobinamide phosphate biosynthesis from Rhodobacter capsulatus suggest that the biosynthetic steps from co(II)byrinic acid a,c-diamide to adocobalamin are the same in both the aerobic and anaerobic pathways. Finally, we increase the vitamin B₁₂ yield of a recombinant E. coli strain by more than ∼250-fold to 307.00 µg g⁻¹ DCW via metabolic engineering and optimization of fermentation conditions. Beyond our demonstration of E. coli as a microbial biosynthetic platform for vitamin B₁₂ production, our study offers an encouraging example of how the several dozen proteins of a complex biosynthetic pathway can be transferred between organisms to facilitate industrial production.

Vitamin B₁₂ is an essential nutrient with limited natural sources. Here the authors transfer 28 pathway synthesis genes from several bacteria including R. capsulatus to E. coli and, using metabolic engineering and optimised fermentation conditions, achieve high yields.

Whole-genome sequencing and comparative analysis of two plant-associated strains of Rhodopseudomonas palustris (PS3 and YSC3)

Rhodopseudomonas palustris strains PS3 and YSC3 are purple non-sulfur phototrophic bacteria isolated from Taiwanese paddy soils. PS3 has beneficial effects on plant growth and enhances the uptake efficiency of applied fertilizer nutrients. In contrast, YSC3 has no significant effect on plant growth. The genomic structures of PS3 and YSC3 are similar; each contains one circular chromosome that is 5,269,926 or 5,371,816 bp in size, with 4,799 or 4,907 protein-coding genes, respectively. In this study, a large class of genes involved in chemotaxis and motility was identified in both strains, and genes associated with plant growth promotion, such as nitrogen fixation-, IAA synthesis- and ACC deamination-associated genes, were also identified. We noticed that the growth rate, the amount of biofilm formation, and the relative expression levels of several chemotaxis-associated genes were significantly higher for PS3 than for YSC3 upon treatment with root exudates. These results indicate that PS3 responds better to the presence of plant hosts, which may contribute to the successful interactions of PS3 with plant hosts. Moreover, these findings indicate that the existence of gene clusters associated with plant growth promotion is required but not sufficient for a bacterium to exhibit phenotypes associated with plant growth promotion.

Characterization of the bafilomycin biosynthetic gene cluster from Streptomyces lohii

New hope for old bones: The plecomacrolide bafilomycin has been explored for decades as an anti-osteoporotic. However, its structural complexity has limited the synthesis of analogues. The cloning of the bafilomycin biosynthetic gene cluster from the environmental isolate Streptomyces lohii opens the door to the production of new analogues through bioengineering.

Production of 5-aminolevulinic acid by Propionibacterium acidipropionici TISTR442

Propionibacterium acidipropionici TISTR442 produced the highest amount of 5-aminolevulinic acid (ALA) when cultivated in medium supplemented with glycine at 18g/l. ALA production correlated with ALA synthase activity, whereas ALA dehydratase activity was maintained at a low level. ALA yield reached 405mg/l after prolonged cultivation for 1 month.

Effects of heme precursors on CYP1A2 and POR expression in the baculovirus/Spodoptera frugiperda system

OBJECTIVE

CYP1A2 and NADPH-CYP450 oxidoreductase (POR) were expressed in the baculovirus/Spodoptera frugiperda (sf9) system. The aim of this study was to investigate the effects of heme precursors on the expression of CYP1A2 and POR.

METHODS

The heme precursors [δ-Aminolaevulinic Acid (5-ALA), Fe(3+) and hemin] were introduced into the system to evaluate their effects on the expression of CYP1A2, POR and their co-expression. All the proteins were identified using immunoblotting, CO-difference spectroscopy, or cytochrome c assay.

RESULTS

In the present study, functional CYP1A2 and POR were successfully expressed in the baculovirus/sf9 system, and both of them showed high activities. Co-addition of 5-ALA and Fe(3+) significantly improved expression of CYP1A2 by about 50% compared with the addition of 5-ALA, Fe(3+) or hemin alone. Either co-addition of 5-ALA and Fe(3+) or addition of 5-ALA or Fe(3+) alone improved the POR expression level 2 fold and its activity 7-10 fold compared with control (no addition). However, unlike CYP1A2, there was no difference between the co-addition and addition of these heme precursors alone. Different ratios of BvCYP1A2 to BvPOR also affected the co-expression of CYP1A2 and POR, with a 3:1 ratio of BvCYP1A2 / BvPOR significantly increasing their co-expression. Surprisingly, the addition of 0.1 mM 5-ALA or Fe(3+) alone, but not their co-addition, could significantly improve the CYP1A2 and POR co-expression (P < 0.05).

CONCLUSION

5-ALA and Fe(3+) increased the expression of CYP1A2 and POR in a baculovirus/sf9 system, but the pattern of their expression was different between their expression alone and co-expression.

Effects of medium composition on production of 5-aminolevulinic acid by recombinant Escherichia coli

The recombinant Escherichia coli BL21(DE3) harboring hemA from Agrobacterium radiobacter, which was engineered in our previous work, was used for the extracellular production of 5-aminolevulinic acid (ALA). The effects of various physiological factors, such as the concentrations of precursors (glycine, succinic acid and glucose) and the inhibitor 5-aminolevulinate dehydratase (levulinic acid), on the ALA accumulation in the fermentation broth were investigated in both shake flasks and a jar fermentor. Among these precursors, glycine exhibited the strongest ability to inhibit cell growth, while glucose mainly inhibited ALA formation. The optimum initial concentrations of glycine, succinic acid and glucose were found to be 2.0, 10.0 and 2.0 g/l, respectively. Levulinic acid (LA; 30 mM) was fed to the fermentation broth at the end of the exponential cell growth phase (about 8 h), and the intracellular activity of ALA dehydratase was efficaciously suppressed. Repeating the optimum composition of the medium in a stirred tank fermenter resulted in 1.49 g/l ALA. Furthermore, the fed batch of the precursors and inhibitor further increased ALA production up to 3.01 g/l.