TABLE 1.

Alginate production by mucD mutantsa

StrainGenotypeAlginate
PAO1mucD+BD
PDO351mucA::aacCI (nonpolar)41.75 ± 12.8
PDO350mucD::aacCIΩ58.42 ± 6.79
PDO354mucD21744.82 ± 4.64
PDO350(pLW37)mucD+ (multicopy)BD
PDO350(pLW67)mucD217 (multicopy)BD
  • a Derivatives of P. aeruginosa PAO1 (wild type) were grown on PIA plates for 48 h at 37°C, and then bacteria and alginate were harvested. The aacCI (gentamicin resistance) cassettes were from Schweizer (28). Plasmids pLW37 and pLW67 were vector pASK-IBA3 (Sigma) containing oriV(SF) for multi-copy, broad-host-range replication (34) and either mucD+ and mucD217, respectively. Alginate was measured in milligrams per milligram of wet cell weight by use of a colorimetric assay (13). BD means that alginate levels were below detection, indicating that the mucD allele was still functioning as a negative regulator.