gene variant mutant Hha13D6 variant of Hha colombos:hha_b0460.13D6_VARIANT PMID: 21255366 a gene variant mutant that with four amino acid replacements at D22V, L40R, V42I and D48A. Hha13D6 was engineered to enhance biofilm dispersal dramatically. Cells with Hha13D6 had enhanced biofilm dispersal at 24, 32 and 48 h, whereas wild-type Hha caused little dispersal after 24 h. Hha13D6 induced acid resistance genes (gadABCEX and hdeABD) and several heat-shock genes including protease genes (clpB, hslOR, hslUV, htpG, ibpAB, lon, prlC and ycjF)