Phosphoribosylpyrophosphate synthetase as a metabolic valve advances Methylobacterium/Methylorubrum phyllosphere colonization and plant growth.

The proficiency of phyllosphere microbiomes in efficiently utilizing plant-provided nutrients is pivotal for their successful colonization of plants. The methylotrophic capabilities of Methylobacterium/Methylorubrum play a crucial role in this process. However, the precise mechanisms facilitating efficient colonization remain elusive. In the present study, we investigate the significance of methanol assimilation in shaping the success of mutualistic relationships between methylotrophs and plants. A set of strains originating from Methylorubrum extorquens AM1 are subjected to evolutionary pressures to thrive under low methanol conditions. A mutation in the phosphoribosylpyrophosphate synthetase gene is identified, which converts it into a metabolic valve. This valve redirects limited C1-carbon resources towards the synthesis of biomass by up-regulating a non-essential phosphoketolase pathway. These newly acquired bacterial traits demonstrate superior colonization capabilities, even at low abundance, leading to increased growth of inoculated plants. This function is prevalent in Methylobacterium/Methylorubrum strains. In summary, our findings offer insights that could guide the selection of Methylobacterium/Methylorubrum strains for advantageous agricultural applications.

Lipidomic analysis reveals differential defense responses of Taxus cuspidata cells to two elicitors, methyl jasmonate and cerium (Ce4+).

Methyl jasmonate (MeJA) and cerium (Ce(4+)) elicitation share common features of increasing taxol accumulation of Taxus cuspidata cells. Interestingly, Ce(4+) induces programmed cell death (PCD), but this phenomenon is not observed with MeJA elicitation. Here, using a lipidomic approach to measure more than 100 membrane glycerophospholipids of T. cuspidata cells quantitatively, we discovered that lysophosphatidylcholine (LysoPC), phosphatidic acid (PA) and phosphatidylcholine were three potential lipid markers that were responsible for the differences between Ce(4+)-induced cells and MeJA-induced cells. Compared with MeJA elicitation, marked increase of phospholipase D (PLD) activity was observed following Ce(4+) elicitation, suggesting that the PLD activation and high concentrations of PA production might mediate the PCD. Rapid increase of phospholipase A(2) (PLA(2)) activity caused the release of fatty acids and LysoPC following Ce(4+) elicitation, which enhanced endogenous jasmonic acid (JA) accumulation. In contrast, PLA(2) activity was poorly induced following MeJA elicitation. PLA(2) inhibitor suppressed not only JA accumulation but also taxol production, suggesting that the PLA(2) activation mediated Ce(4+)-induced taxol production partially through a JA-dependent signaling pathway. These results demonstrate that differential alternation of glycerolphospholipids caused by phospholipases constitutes an important step in cell death response to Ce(4+) and increasing taxol production.

Comparative Metabolic Responses Induced by Pyridine and Imidazole in Blakeslea trispora.

Lycopene cyclase needs to be inhibited by the blockers like pyridine or imidazole in the lycopene accumulation of Blakeslea trispora. This work investigated how pyridine and imidazole impacted the basal metabolism of B. trispora, the results helped us understand how they could affect the lycopene production and application, and see the metabolic risks from different inhibitors. In this study, the highest yield of lycopene with pyridine was obtained at 176 mg/L without amino acids supplement, and got more lycopene at 237 mg/L adding tyrosine, lysine, proline all together as 0.01 mol/L each in fermented broth. GC-MS and Principal Component Analysis (PCA) were used to find that amino acids, fatty acids, organic acids including phosphoric acid, carbon source and imidazole derivatives played the most important roles in lycopene fermentation with imidazole, differently, fatty acids, carbon source, and pyridine derivatives were more significant in the pyridine process and it was remarkable that the residual of both blockers' derivatives would bring the potential risks on applications of lycopene products. Predominantly, durene met 0.35 mg/g DCW with imidazole and piperidine formaldehyde attained 0.24 mg/g DCW with pyridine after the end of lycopene fermentations.

Microencapsulated ß-carotene preparation using different drying treatments.

ß-Carotene is one of the most abundant natural pigments in foods; however, usage of ß-carotene is limited because of its instability. Microencapsulation techniques are usually applied to protect microencapsulated ß-carotene from oxidization. In this study, ß-carotene was microencapsulated using different drying processes: spray-drying, spray freeze-drying, coating, and spray granulation. The properties of morphology, particle size, water content, thermal characteristic, and chemical stability have been explored and compared. Scanning electron microscopy measurements showed that the coated powder had a dense surface surrounded by starch and suggested that the coating process gave a microencapsulated powder with the smallest bulk density and the best compressibility among the prepared powders. The chemical stabilities of microcapsules were evaluated during six months of storage at different temperatures. The coated powder had the highest mass fraction of ß-carotene, which indicated that the coating process was superior to the three other drying processes.

Lipid Distribution Pattern and Transcriptomic Insights Revealed the Potential Mechanism of Docosahexaenoic Acid Traffics in Schizochytrium sp. A-2.

Schizochytrium sp. A-2 is a heterotrophic marine fungus used for the commercial production of docosahexaenoic acid (DHA). However, the pattern of the distribution of DHA and how DHA is channeled into phospholipid (PL) and triacylglycerol (TAG) are unknown. In this study, we systematically analyzed the distribution of DHA in TAG and PL during the growth of the cell. The migration of DHA from PL to TAG was presumed during the fermentation cycle. DHA and docosapentaenoic acid were accumulated in both TAG and phosphatidylcholine (PC), whereas eicosapentaenoic acid was mainly deposited in PC. RNA seq revealed that malic enzyme may provide lipogenic NADPH. In addition, long-chain acyl-CoA synthase and acyl-CoA:lysophosphatidylcholine acyltransferase may participate in the accumulation of DHA in PL. No phosphatidylcholine:diacylglycerol cholinephosphotransferase was identified from the genome sequence. In contrast, phospholipid:diacylglycerol acyltransferase-mediated acyl-CoA-independent TAG synthesis pathway and phospholipase C may contribute to the channeling of DHA from PC to TAG.

Comparative lipidomics analysis of cellular development and apoptosis in two Taxus cell lines.

A comparative lipidomics approach was employed to investigate the changes in membrane phospholipids during the procession of cellular development and apoptosis of two plant cell lines, Taxus cuspidata and Taxus chinensis var. mairei. Analysis of lipids by LC/ESI/MS(n) showed more than 90 phospholipid molecular species and indicated significant differences in the abundance throughout a 3-week period. Phosphatidic acid (PA), phosphatidylcholine (PC) and lysophosphatidylcholine (LysoPC) were three important lipid groups that were responsible for the discrimination between the apoptotic T. chinensis var. mairei and living T. cuspidata cells. Continuous increase of phospholipase D (PLD) activity led to PA production in apoptotic T. chinensis var. mairei cells suggesting that the PLD activation and PA formation mediated the apoptosis. Comparison of the profiles of phosphatidylbutanol (PtdBut) with those of PC or phosphatidylethanolamine (PE) indicated that PC rather than PE was the major substrate of PLD in vivo. These results suggest that the alternation of membrane phospholipids may regulate apoptosis, triggering an increase in taxol production of T. chinensis var. mairei cells.

Cerium elicitor-induced phosphatidic acid triggers apoptotic signaling development in Taxus cuspidata cell suspension cultures.

Degradation of membrane phospholipids is associated with apoptotic responses, but the signaling development of this degradation is not well understood. Cerium (Ce(4+)), an important rare earth element, induces cellular apoptosis and taxol biosynthesis in Taxus cuspidata suspension cultures. Here, using mass spectrometry and biochemical technique, we demonstrated that the phospholipase D (PLD) was rapidly activated by Ce(4+) and hydrolyzed structural phospholipids to generate lipid signal molecule, phosphatidic acid (PA). 1-Butanol, an antagonist of PLD-dependent PA production, blocked the biphasic burst of superoxide anions (O2(*-)) and thus mitigated cellular apoptosis. The time-course analysis of PA accumulation and ERK-like mitogen-activated protein kinase (MAPK) regulation indicated PA generation preceded MAPK activation, suggesting that the rapid accumulation of PA might be required for the initial MAPK activity. After 2h of Ce(4+) elicitation, however, PA-induced O2(*-) burst, forming a negative regulation to MAPK activity, which in turn led to apoptotic signaling development.