Highly stable, 100 W average power from fiber-based ultrafast laser system at 1030 nm based on single-pass photonic-crystal rod amplifier

We report on a fiber-based, Yb-doped, ultrafast laser system capable of outputting 100 W average power at a repetition rate of 500 kHz. The system uses chirped pulse amplification, employing a custom-made pulse-stretching fiber and a grating based compressor, to generate highly energetic, 330 fs pulses at 1030 nm. A diode-pumped photonic-crystal rod delivers amplification of pulses up to 400 μJ while maintaining near diffraction-limited mode quality. The system is highly robust and offers excellent short and long term power stability

Evaluation of Bacillus subtilis strain IS53 for the production of Bacillus anthracis protective antigen

An asporogenous strain of Bacillus subtilis, IS53, transformed with plasmid pPA102, produces the protective antigen (PA) component of the tripartite toxin of B. anthracis. Addition of yeast extract was required to support growth and PA production in all the media examined. Protective antigen expression was down-regulated during exponential growth and extracellular proteases caused marked degradation of the mature protein

Production and purification of recombinant protective antigen and protective efficacy against Bacillus anthracis

Recombinant protective antigen (rPA), expressed by Bacillus subtilis WB600 (pPA101), has been purified to homogeneity and the protective efficacy against a Bacillus anthracis challenge has been investigated. rPA was fractionated from culture supernatant fluid by ammonium sulphate, followed by anion exchange chromatography using DEAE Streamline™, anion-exchange chromatography on FPLC MonoQ HR 10/10 and finally, gel filtration chromatography on FPLC Superose 12 HR 10/30, to yield 7 mg rPA per litre of culture. The protective efficacy of rPA against an airborne challenge with the AMES strain of B. anthracis was determined in the presence of the adjuvants, alhydrogel and Ribi, and compared to that achieved by the current UK human vaccine in guinea pigs. rPA combined with the Ribi adjuvant was found to provide 100% protection against challenge