Analysis of nicotine-induced metabolic changes in Blakeslea trispora by GC-MS.

Blakeslea trispora is a natural source of carotenoids, including ß-carotene and lycopene, which have industrial applications. Therefore, classical selective breeding techniques have been applied to generate strains with increased productivity, and microencapsulated ß-carotene preparation has been used in food industry (Li et al., 2019). In B. trispora, lycopene is synthesized via the mevalonate pathway (Venkateshwaran et al., 2015). Lycopene cyclase, which is one of the key enzymes in this pathway, is a bifunctional enzyme that can catalyze the cyclization of lycopene to produce ß-carotene and exhibit phytoene synthase activity (He et al., 2017).

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.

Genome shuffling and ribosome engineering of Streptomyces virginiae for improved virginiamycin production.

The production of virginiamycin (VGM) from Streptomyces virginiae was improved by genome shuffling and ribosome engineering companied with a high-throughput screening method integrating deep-well cultivation and the cylinder-plate detecting. First, a novel high-throughput method was developed to rapidly screen large numbers of VGM-producing mutants. Then, the starting population of genome shuffling was obtained through ultraviolet (UV) and microwave mutagenesis, and four mutants with higher productivity of VGM were selected for genome shuffling. Next, the parent protoplasts were inactivated by UV and heat when a fusant probability was about 98%. Streptomycin resistance was used as an evolutionary pressure to extend positive effects on VGM synthesis. Finally, after five rounds of genome shuffling, a genetically stable strain G5-103 was obtained and characterized to be able to yield 251 mg/L VGM, which was 3.1- and 11.6-fold higher than that of the mutant strain UV 1150 and the wild-type strain, respectively.

Bipedicle orbicularis oculi flap in the reconstruction of the lower eyelid ectropion.

BACKGROUND: Lower eyelid ectropion is conventionally reconstructed with a local flap or full-thickness skin graft. However, scar contracture and recurrence of ectropion often occur. This article describes an effective surgical technique for lower eyelid ectropion repair using a bipedicle orbicularis oculi muscle or myocutaneous flap from the upper eyelid. METHODS: This study prospectively analyzed collected data on the bipedicle orbicularis oculi muscle or myocutaneous flap from the upper eyelid in reconstruction of lower eyelid ectropion between 1995 and 2004. The flap was used in 12 eyelid procedures for the correction of lower eyelid ectropion, in 10 cases with traumatic ectropion, and in 1 case with bilateral congenital ectropion. In these cases, a strip of orbicularis oculi muscle or a myocutaneous flap from the upper eyelid with two pedicles attached in the medial and lateral canthus was advanced to the lower eyelid to suspend the eyelid and repair the skin defect. RESULTS: No problem of flap viability was encountered in any of the patients, and all healed well. Deformities were corrected, and evaluation showed satisfactory function and appearance during 0.5 to 6 years (average, 2 years) of follow-up evaluation. Eyelid malposition and bulkiness of the lower eyelid occurred in the early stages, but disappeared gradually about 3 months after the operation. There was no flap contraction, recurrent deformity, or significant donor site morbidity in the follow-up period. The incision scars were almost invisible. CONCLUSIONS: The application of bipedicle orbicularis oculi muscle or a myocutaneous flap from the upper eyelid in reconstruction of lower eyelid ectropion is effective and reduces postoperative morbidity.

A novel approach for improving the productivity of ubiquinone-10 producing strain by low-energy ion beam irradiation.

Agrobacterium tumefaciens ATCC4452 cells were irradiated by nitrogen ion beam, a new mutagen, with energy of 10 keV and fluence ranging from 2.6x10(14) ions/cm2 to 6.5x10(15) ions/cm2. A similar "saddle shape" survival curve due to ion beam irradiation appeared again in this study. Some mutants with high yield of ubiquinone-10 were induced by ion implantation. High mutation rate and wide mutation spectrum were also observed in the experiment. These results suggested that the mutagenic effect of such low-energy ion influx into bacterium cells could result from multiple processes involving direct collision of particles with cytoplasm, nucleolus, and cascade atomic and molecular reactions due to plentiful primary and secondary particles.

Studies on Etching and Damage Action of Low Energy Ion Beam on icrobial Cells.

The action of 20 keV N(+) ion on Deinococcus radiodurans and E. coli was investigated by means of scanning electron microscope(SEM) and electron spin resonance(ESR). The results showed that ion implantation exerted direct etching damage and indirect free radicals action by energy deposition on the cells of the two microbes. The DNA damage and biological mutation resulted mainly from the etching action of injected ions; the free radicals resulted chiefly in the damage of peroxidation of biological macromolecule and membrane lipids except of DNA. Moreover, the damages in D. radiodurans and E. coli by etching and free radicals action aggravated gradually with increasing doses. The sedimentation patterns of tritiated DNA materials in D. radiodurans by neutral sucrose gradient(50-200 g/L) indicated that DNA sedimentation peak of cells incubated for 4 h did not resume control state after the implantation of 60x10(15) N(+) ions injection per cm(2), proving that the direct action of implanted ions led to DNA damage. The survival rate of the implanted D. radiodurans and E. coli lowered after 2 mol/L caffeine and 0.5 mmol/L EDTA treatment, confirming that the etching action of implanted ions was the direct cause resulting in DNA damage and organism mutation.