Co-culture of Bacillus amyloliquefaciens and recombinant Pichia pastoris for utilizing kitchen waste to produce fengycins.

Kitchen waste (KW) is a vast potential source of fermentable substrates. To bio-convert the KW into high-value chemicals, we used KW as substrate for the production of fengycin by an artificial consortium containing Bacillus amyloliquefaciens HM618 producing fengycin and the engineering Pichia pastoris producing amylase, glucosidase, or lipases. The maximal amylase activity of the constructed amylase-producing engineering strain (recombinant P. pastoris GS115-amy98) reached 385.4 U‧mL. The engineering strain GS115-α-glu53 producing glucosidase reached an enzyme activity titer of 247.3 U‧mL, while the lipase activities of the engineering strains GS115-lip2, GS115-α-lip2, and GS115-lip7 were around 90.0 U‧mL, with no significant differences among them. Liquid chromatography-mass spectrometry (LC-MS) analysis showed that the components of fengycin synthesized by B. amyloliquefaciens HM618 were complex, including C14-C18 fengycins A, C13-C14 fengycins B, C16-C18 fengycins B, C16 fengycin B2 and some fengycin homologues with unsaturated fatty acid chains. The levels of fengycin were 15.9 mg‧L and 4.6 mg‧L under the co-culture with strain HM618 and the recombinant strains producing amylase and lipase, respectively. The maximal titer of fengycin was 21.2 mg‧L in the artificial consortia consisting of HM618 and the engineering strains producing glucosidase, amylase and lipase. Taken together, these results show that the co-culture of B. amyloliquefaciens HM618 and engineering strains producing amylase and lipase can promote the conversion of KW into fengycin. The work provides a new strategy for boosting the resource utilization of KW.