Abstract
BackgroundBenzoic acid is one of the most useful aromatic compounds. Despite its versatility and simple structure, benzoic acid production using microbes has not been reported previously. Streptomyces are aerobic, Gram-positive, mycelia-forming soil bacteria, and are known to produce various kinds of antibiotics composed of many aromatic residues. S. maritimus possess a complex amino acid modification pathway and can serve as a new platform microbe to produce aromatic building-block compounds. In this study, we carried out benzoate fermentation using S. maritimus. In order to enhance benzoate productivity using cellulose as the carbon source, we constructed endo-glucanase secreting S. maritimus.ResultsAfter 4 days of cultivation using glucose, cellobiose, or starch as a carbon source, the maximal level of benzoate reached 257, 337, and 460 mg/l, respectively. S. maritimus expressed β-glucosidase and high amylase-retaining activity compared to those of S. lividans and S. coelicolor. In addition, for effective benzoate production from cellulosic materials, we constructed endo-glucanase-secreting S. maritimus. This transformant efficiently degraded the phosphoric acid swollen cellulose (PASC) and then produced 125 mg/l benzoate.ConclusionsWild-type S. maritimus produce benzoate via a plant-like β-oxidation pathway and can assimilate various carbon sources for benzoate production. In order to encourage cellulose degradation and improve benzoate productivity from cellulose, we constructed endo-glucanase-secreting S. maritimus. Using this transformant, we also demonstrated the direct fermentation of benzoate from cellulose. To achieve further benzoate productivity, the L-phenylalanine availability needs to be improved in future.
Highlights
Benzoic acid is one of the most useful aromatic compounds
The peak of benzoic acid in the standard sample was found at about 8 min (Lane 1), which was observed in the culture supernatant of S. maritimus/WT (Lane 2)
The UV spectra of the benzoic acid fraction separated from the culture supernatant of S. maritimus/WT exhibit two major absorption peaks in the region of 190–300 nm, similar to the standard sample of benzoic acid (Figure 2(B))
Summary
Benzoic acid is one of the most useful aromatic compounds. S. maritimus possess a complex amino acid modification pathway and can serve as a new platform microbe to produce aromatic building-block compounds. In order to enhance benzoate productivity using cellulose as the carbon source, we constructed endo-glucanase secreting S. maritimus. Benzoic acid is one of the most useful aromatic compounds, and can be converted to terephthalic acid by the Henkel reaction [8], epsilon-caprolactam by the Snia Viscosa process [9], and phenol by a decarbonation reaction [10]. Despite its versatility and simple structure, benzoic acid production using microbes has not been reported previously
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
