Abstract: A polynucleotide having promoter activity of a malate dehydrogenase gene (mdh gene), a transcription expression cassette, recombinant expression vector and recombinant host cell containing the polynucleotide having the promoter activity, a method for constructing a promoter mutant, a method for regulating the transcription of a target gene, a method for preparing a protein, and method for producing a target compound. The polynucleotide having the promoter activity is a mutant of an mdh gene promoter, and compared with a promoter of a wild-type mdh gene, the promoter activity of the mutant is significantly improved. After operably linking the mutant to a target gene, the expression efficiency of the target gene can be significantly improved, thereby effectively improving the yield and transformation rate of a target compound.

Abstract: A volute device, including: an intake passage including an inner passage and an outer passage; a gas inlet including a first gas inlet and a second gas inlet; and a gas outlet. The gas inlet is disposed at one end of the intake passage, and the gas outlet is disposed at the other end of the intake passage. A first inner passage and a first outer passage communicate with the first gas inlet to suck gas in a semicircle of a circumference direction at between 0° and 180°. A second inner passage and a second outer passage communicate with the second gas inlet to suck gas in another semicircle of the circumference direction at between 180° and 360°.