(582bb) Efficient Production and Molecular Design of Microbial Surfactants for Next-Generation Biochemicals

Biosurfactants (BSs) are amphiphilic compounds produced from carbon neutral materials by microorganisms. The compounds have excellent surface active properties and a great potential for applications in cosmetics, pharmaceutical and food industries. We have isolated several types of BS producing microorganisms to investigate the diversity of BS producing microorganisms the variety of molecular structures of BSs. Mannosylerythritol lipids (MELs) produced by several species in the genera Pseudozyma in basidiomycetus yeast have a variety of the major products. Pseudozyma antarctica, Ustilago maydis, and related species produces 4-O-[4’, 6’-O-diacetyl-2’,3’di-O-alka(e)noyl-β-D-mannopyranosyl]-D-erythritol, named MEL-A, and Pseudozyma hubeiensis produces 4-O-[4’-O-acetyl-2’,3’di-O-alka(e)noyl-β-D-mannopyranosyl]-D-erythritol, named MEL-C. We have isolated Pseudozyma hubeiensis SY62 from deep-sea. SY62 produce 129 g/L of MELs from glucose and olive oil after optimization of the culture conditions. The productivity of MELs by SY62 is the highest record in published papers in the best of our knowledge. SY62 is one of candidates for mass production of MEL in industrial process.

In order to investigate the difference of molecular structure of major MELs secreted, draft genome sequencing of a good MEL producing strain, SY-62, in P. hubeiensis were performed by Illumina HiSeq system in this study. The sequence reads from pair-end library (400 bp) were initially assembled into 74 contigs using Augstus v1.2.08. The contigs total genome size of 18,442,938 bp. The G+C content were 56.5%. The cording regions and their functions were predicted using MetaGeneAnnotator 1.0 and NCBI BLAST 2.2.18. The rRNA and tRNA genes were found using RNAmmer and tRNAscan, respectively. The draft genome is composed of 7,523 putative-coding genes or open reading frames (ORFs), 26 rRNA and 121 tRNA genes. The genes of the cluster, emt1, mac1, mac2, mmf1, and mat1 were observed in the genome of P. hubeiensis SY62. These translated amino acids sequences shows identities of 79.7, 71.6, 62.1, 82.2, and 57.8% to the corresponding genes in U. maydis. The low identity of Mat1 between P. hubeiensis and U. maydis seemed to associate the differences of the specificity of acetyltransferase and the resulting difference of acetylation of major products.

We are developing deleted mutants producing the variety of MEL intermediates in the synthetic pathway. The intermediates will enhance the diversity of MEL derivatives. We aim to develop a designable biosurfactant production of SY62 using draft sequencing and deleted mutation. We discuss the designable biosurfactant production concept in this presentation.