Journal of Food, Agriculture and Environment

Vol 12, Issue 2,2014
Online ISSN: 1459-0263
Print ISSN: 1459-0255

Production of L-lysine by Brevibacterium lactofermentum and its application in eco-friendly synthesis of gold nanoparticles using gamma radiation


Ahmed I. El-Batal 1, Roquia Al-Habib 2

Recieved Date: 2014-01-11, Accepted Date: 2014-04-02


The target of the present investigation was to optimise the modified fermentation medium composition (different carbon, nitrogen and mineral sources) for L-lysine production by Brevibacterium lactofermentum mutant strain in submerged fermentation. Also, the two factors affected L-lysine production, such as biotin as a metabolic activator and L-alanine as a metabolic regulator, were studied to increase the rate of production. The most effective components for L-lysine biosynthesis were selected and the optimal concentrations of these components were determined under the optimised conditions and modified fermentation medium of (20% molasses as a carbon source, 3% ammonium sulphate, 3% CaCO3 , 400 µg l-1 biotin and 75 mg% L-alanine) with maximum L-lysine (40.6 g l-1) yield. Stimulatory effect in L-lysine production was observed when low concentrations of some surface active agents as membrane and cell wall permeability enhancers of Tween (20, 40, 60 and 80) and Triton X-100, as well as organic solvent dimethylsulfoxide (DMSO) were added at various concentrations during the process of fermentation. The addition of Tween-60 (0.1%, v/v) after 10 h of cultivation gave the highest L-lysine yield (50.0 g l-1) after 4 days of incubation time under the optimised conditions of the modified fermentation medium. L-lysine aqueous solution, which was used as reducing and stabilising agent, stimulated eco-friendly synthesis of gold nanoparticles (AuNPs) using radiolytic reactions of gamma radiation. The incorporation of L-lysine with AuNPs was confirmed by UV-visible, dynamic light scattering (DLS), Fourier Transform infra red (FT-IR) and spectrophotometers. Also, transmission electron microscope (TEM) analysis revealed morphology of well dispersed spherical AuNPs with size ranging from 6.79 nm to 9.54 nm with mean diameter of 8.73 nm.


L-lysine, Brevibacterium lactofermentum mutant strain, submerged fermentation, surface active agents, gold nanoparticles, gamma radiation

Journal: Journal of Food, Agriculture and Environment
Year: 2014
Volume: 12
Issue: 2
Category: Food and Health
Pages: 141-149

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