Production of L-tryptophan for food, feed, and pharmaceutical applications

Abstract

Background: L-tryptophan can be utilized in a variety of applications. The prevalence of L-tryptophan in diverse sectors, including chemical, pharmaceutical, food and feed industries, underscores its significance. The predominant method of producing L-tryptophan involves microbial fermentation, which requires establishing an effective culture of microorganisms.

Objective: This study focuses on Brevibacterium flavum C18 characterization and the technological parameter optimization for the biotechnological deriving of L-tryptophan.

Methods: m-Fluorophenylalanine- and 5-fluorotryptophan-resistant C18 (m-FPr, 5-FTr) were characterized by a range of morphological and biochemical properties. A microbiological assay evaluated the potential of this strain to synthesize L-tryptophan. The effect of antibiotics on the strain was determined by agar disk diffusion assay. Finally, the fermentation was optimized by varying the agitation speed of the incubator shaker during shake-flask fermentation. 

Results: C18 was found to be non-motile, gram-positive, and prototrophic. This strain was synthesized from L-tryptophan through the utilization of microbiological testing methodologies. 

Conversely, C18 exhibited a positive response in the catalase test, as indicated by the citrate test, gelatin, and starch liquefaction tests. The strain demonstrated sensitivity to kanamycin, tetracycline, and vancomycin. Furthermore, the strain demonstrated heightened sensitivity to gentamicin and erythromycin. 

The highest yield of L-tryptophan (up to 7.8 g/l) by C18 was achieved at a stirring rate of 220 rpm in shake-flask fermentation.

This research allowed assessing the impact of agitation speed on L-tryptophan production using producer C18. The study indicates that, compared to the described strains, L-tryptophan production has been enhanced by a safe producer that is more resilient and adaptable to environmental conditions.

 Conclusion: The investigation has demonstrated that C18 is characterized by a combination of morphological and biochemical properties. Furthermore, it was determined that the synthesis of L-tryptophan was optimized by agitation speed, with the maximum amount of the target amino acid being recorded at a speed of 220 rpm. The subject strain may hold significant promise in terms of its potential for application in the nutritional and pharmaceutical sectors.

Keywords: Brevibacterium flavum, morphological and biochemical characteristics, agitation speed, L-tryptophan production, bioactive compound.