Study On The Process And Mechanism Of Ultrasound Stimulation Enhanced Naringinase Fermentation Via Aspergillus Niger

Naringinase is an important biological enzyme preparation,which is widely used in the biological food industry.In order to improving the activity of naringinase,the process of naringinase fermentation via Aspergillus niger was studied by ultrasonic treatment strategy.Based on the results of the single factor experiment,the ultrasonic treatment process was optimized by response surface methodology,and the molecular mechanism of enhancing the activity of naringinase by ultrasonic treatment was further studied by RT-PCR technology.Based on the results of the single factor experiment,Box-Behnken experiment was designed with five factors and three levels.Response surface methodology was used to analyze the effects of various factors on the activity of naringinase,taking ultrasound stimulation stage,power,duration,times and interval as dependent variables and the activity of naringinase as response value.The optimized parameters were the ultrasonic stimulation stage of 27 h,the ultrasonic power and ultrasonic duration of 160 w and 14 min,second times of ultrasonic stimulation,and the ultrasonic time interval of 13 h,and the activity of naringinase reached 1059.20 U/mL,which was 23.16% higher than that of non-ultrasonic treatment.The rhamnosidase gene(RHA)of Aspergillus Niger treated by ultrasonic stimulation was further extracted and the expression of RHA was compared with that of non-ultrasonic stimulation by RT-PCR.It was indicated that the expression of RHA changed sharply after repeated ultrasound treatment,and it reached the highest level at two times of ultrasonic stimulation treatment.The changes of ultrasonic stimulation on the activity of naringinase were similar as those of RHA,which illuminated that ultrasonic stimulation enhanced naringinase activity through influencing the expression of RHA.This study explored the effects of ultrasound stimulation on the expression of genes related to naringin-producing enzymes in Aspergillus niger.In order to further study the naringin fermentation strategy and promote its industrialization in the field of food processing and biocatalysis research,it provides basic data and technical support.