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This work aimed to explore low-intensity ultrasound-assisted adaptive laboratory evolution (US-ALE) of Bacillus velezensis and fermentation performance of mutant strains were investigated by nitrogen transformation metabolism. Results showed ultrasound accelerated the process of adaptive evolution and enhanced cell dry weight, amylase and protease activity of mutant strains, accompanied with the improved transformation abilities of NO–3-N to NH4+-N. Compared with original strain, the total peptide-N, peptide-N (

The effects of power ultrasound (US) pretreatment on the preparation of soy protein isolate hydrolysate (SPIH) prepared at the same degree of hydrolysis (DH) of 12 % were measured. Cylindrical power ultrasound was modified into mono-frequency (20, 28, 35, 40, 50 kHz) ultrasonic cup coupled with an agitator to make it applicable for high density SPI (soy protein isolate) solutions (14 %, w/v). A comparative study of the alterations of the hydrolysates molecular weight, hydrophobics, antioxidants and functional properties change as well as their relation were explored. The results showed that under the same DH, ultrasound pretreatment decelerated the degradation of protein molecular mass and the decrease rate of the degradation lessened with the increase of ultrasonic frequency. Meanwhile, the pretreatments improved the hydrophobics and antioxidants properties of SPIH. Both surface hydrophobicity (H0) and relative hydrophobicity (RH) of the pretreated groups increased with the decrease of ultrasonic frequency. Lowest frequency (20 kHz) ultrasound pretreatment had the most improved emulsifying properties and water holding capacities, although decrease in the viscosity and solubility were found. Most of these alterations were correspondence toward the change in hydrophobics properties and molecular mass. In conclusion, the frequency selection of ultrasound pretreatment is essential for the alteration of SPIH functional qualities prepared at the same DH.

Low-lethality ultrasound technology has received more and more attention in regulating microorganisms of fermentation industry. Herein, two representative Ames tester strains TA97a and TA98 as model organisms were used to explore the effects of ultrasound on insertion-deletion (InDel) polymorphisms of microbial DNA and its underlying mechanisms. Results revealed that a promotion was observed in the reversion mutation of TA98 upon sonication. Sequencing results from 1752 TA98 revertants showed that there was a total of 127 InDels, of which the InDels unique to ultrasound were 36 more than that of the control. Compared with the control, ultrasound-mediated InDels of DNA displayed additional −29 bp deletion and +7 ∼ +43 bp insertions of direct repeat sequences. Combined with the analysis of transcriptomics and prediction of secondary structure of single-stranded DNA from InDels core region (No. 832 ∼ 915 bp) in hisD3052 gene of TA98 strain, ultrasound-mediated “thermal breathing” mechanism was proposed based on the formation of DNA hairpin structure with micro-homologous sequence. This finding implied that low-intensity ultrasound is expected to be developed a new low-lethal mutagenic technology for continuous mutagenesis.

Cr and Al coating were respectively deposited on Zr-4 alloy by magnetron sputtering and high temperature oxidation (HTO) tests were conducted in air environment at 1200 °C for 3 h for Cr-coated and Al-coated specimens. The morphology and phase composition of the specimens were detected by SEM, EDS and XRD. The adhesion properties were characterized by scratch test. The XRD results revealed that the two coatings were crystalline with preferred orientation. The results of scratch testing showed that critical load of Cr coating was higher than that of Al coating. After HTO test, the Cr-coated specimen was intact without cracking and spalling off, only the outermost layer of Cr coating was oxidized to a Cr2O3 layer of about 4 μm thick with a residual Cr layer of about 4 μm thick, and the internal zirconium alloy was not oxidized. For Al-coated specimen, besides the complete oxidation of the Al coating, there were also about 500 μm Zr-4 alloy oxidized on each side, and there were a lot of voids and cracks in the specimen. The EDS results indicated that a thickness of about 5 μm Cr-Zr diffusion layer developed at the interface between Cr coating and Zr-4 alloy for the Cr-coated Zr-4 specimen. While, for the Al-coated Zr-4 specimen, Al diffused into the specimen to a depth of about 100 μm, and Zr diffused almost to the outermost layer. Moreover, Sn in the Zr-4 alloy is concentrated at the interface between the residual Zr-4 alloy and ZrO2 layer. The obtained results manifested that Cr coating shows better oxidation resistance than Al coating.

Prime-editing systems have the capability to perform efficient and precise genome editing in human cells. In this study, we first developed a plant prime editor 2 (pPE2) system and test its activity by generating a targeted mutation on an HPT-ATG reporter in rice. Our results showed that the pPE2 system could induce programmable editing at different genome sites. In transgenic T0 plants, pPE2-generated mutants occurred with 0%–31.3% frequency, suggesting that the efficiency of pPE2 varied greatly at different genomic sites and with prime-editing guide RNAs of diverse structures. To optimize editing efficiency, guide RNAs were introduced into the pPE2 system following the PE3 and PE3b strategy in human cells. However, at the genomic sites tested in this study, pPE3 systems generated only comparable or even lower editing frequencies. Furthemore, we developed a surrogate pPE2 system by incorporating the HPT-ATG reporter to enrich the prime-edited cells. The nucleotide editing was easily detected in the resistant calli transformed with the surrogate pPE2 system, presumably due to the enhanced screening efficiency of edited cells. Taken together, our results indicate that plant prime-editing systems we developed could provide versatile and flexible editing in rice genome.