Disclosed are Paenibacillus strains comprising a reduced activity of a flippase PepR aflippase PepH, a mannose-1-phosphate guanylyl transferase and/or a levansucrase SacB. These Paenibacillus strains show lower viscosity when grown in liquid culture and agricultural compositions comprising these strains and methods of making and using these strains.

The invention provides an oligosaccharide debranching enzyme mutant and use thereof in a glucose mother liquor. The mutant is obtained by mutating valine at position 219 in SEQ ID NO: 1 into alanine. According to oligosaccharide debranching enzyme mutant V219A, a primary mother liquor, a secondary mother liquor, or a tail liquid after chromatographic separation is used as a substrate, the percentage contents of glucose in the products are 99.21% (primary mother liquor), 98.89% (secondary mother liquor) and 97.97% (tail liquid after chromatographic separation) respectively, which are 2.86%, 8.64%, and 28.67% higher than that of glucose obtained with the wild-type oligosaccharide debranching enzyme. Therefore, the mutant V219A obviously improves the percentage content of glucose in the glucose mother liquor, and the scope of application of the mother liquor can be expanded by the high product purity and substrate conversion rate, so the mutant V219A has higher industrial application value.

Disclosed are a method for screening a riboswitch capable of specifically recognizing doxycycline as well as rational engineering and application of the riboswitch, and belongs to the field of gene expression regulation. The present disclosure provides a doxycycline specific riboswitch, and establishes a high-throughput screening method based on flow cytometry, and obtains the doxycycline riboswitch with further improved activation fold by way of computer-aided prediction of binding sites of the riboswitch and calculation of mutation sites. According to a dose-response curve, the riboswitch shows linear correlation at 40-100 g/L, and meanwhile, a whole-cell sensor constructed is low in price, high in stability and simple to operate, and can be used for on-site rapid detection.