Abstract:[Background] Biogenic natural pigments have potential applications in industry, agriculture, and textile industries. [Objective] The isolation and screening of marine pigment-producing actinobacteria is aimed to lay a foundation for the applications of bacterial pigments in the textile and food industry. [Methods] Actinobacteria, producing extracellular soluble pigment, were screened, and 16S rRNA gene phylogenetic tree was constructed based on their 16S rRNA gene sequences. Subsequently, factors affecting pigment yield and stability were investigated. [Results] A blue pigment-producing actinobacterium Q2N-42 and a yellow-green pigment-producing actinobacterium X4C-5 were obtained. Phylogenetic analyses of the 16S rRNA gene sequences of Q2N-42 and X4C-5 showed that they have high similarity with Streptomyces coelicolor or Streptomyces violaceoruber and Streptomyces pratensis, respectively. Comparative analyses of the effects of carbon and nitrogen sources on pigment yields showed that glycerol and sodium nitrate can significantly increase the blue pigment yield of S. coelicolor Q2N-42, whereas, starch and sodium nitrate can significantly increase the yellow-green pigment yield of S. pratensis X4C-5. Both the blue and yellow-green bacterial pigments displayed fine stability when they were treated with different concentrations of the oxidant, reductant, salinity, and pH. FTIR spectral analyses of the pigments showed that the pigment molecules contain the functional groups of ?OH, ?CH3, and C=C. Different mordants coupled with the bacterial pigments were used to check the dyeing propriety on the cotton threads. The results demonstrated that copper sulfate combined with the bacterial blue pigment presented a excellent performance when the cotton threads were dyed with it, the cotton threads were stained in darker blue, and enough to withstand the water wash treatment. Whereas, ferrous sulfate combined with the bacterial yellow-green pigment gave a good performance for the cotton thread staining. [Conclusion] Those data indicate that both the blue pigment produced by Q2N-42 and the yellow-green pigment produced by X4C-5 are potential resources towards their industrial applications.
