A Bacterial Virus for Actinomyces griseus

Bacteriophage Challenges in Industrial Processes: A Historical Unveiling and Future Outlook

Humans have used fermentation processes since the Neolithic period, mainly to produce beverages. The turning point occurred in the 1850s, when Louis Pasteur discovered that fermentation resulted from the metabolism of living microorganisms. This discovery led to the fast development of fermented food production. The importance of industrial processes based on fermentation significantly increased. Many branches of industry rely on the metabolisms of bacteria, for example, the dairy industry (cheese, milk, yogurts), pharmaceutical processes (insulin, vaccines, antibiotics), or the production of chemicals (acetone, butanol, acetic acid). These are the mass production processes involving a large financial outlay. That is why it is essential to minimize threats to production. One major threat affecting bacteria-based processes is bacteriophage infections, causing substantial economic losses. The first reported phage infections appeared in the 1930s, and companies still struggle to fight against phages. This review shows the cases of phage infections in industry and the most common methods used to prevent phage infections.

Bacteriophage-resistant industrial fermentation strains: from the cradle to CRISPR/Cas9

Bacteriophage contamination and cell lysis have been recurring issues with some actinomycetes used in the pharmaceutical fermentation industry since the commercialization of streptomycin in the 1940s. In the early years, spontaneous phage-resistant mutants or lysogens were isolated to address the problem. In some cases, multiple phages were isolated from different contaminated fermentors, so strains resistant to multiple phages were isolated to stabilize the fermentation processes. With the advent of recombinant DNA technology, the early scaleup of the Escherichia coli fermentation process for the production of human insulin A and B chains encountered contamination with multiple coliphages. A genetic engineering solution was to clone and express a potent restriction/modification system in the production strains. Very recently, an E. coli fermentation of 1,3-propanediol was contaminated by a coliphage related to T1. CRISPR/Cas9 technology was applied to block future contamination by targeting seven different phage genes for double-strand cleavage. These approaches employing spontaneous mutation, genetic engineering, and synthetic biology can be applied to many current and future microorganisms used in the biotechnology industry.

The B. mycoides N host-virus system. I. Differences in appearance and "rate of growth" of the lysogenic and parent indicator strains

There were differences in the way the lysogenic strain N of B. mycoides and the parent indicator strain grew on nutrient agar and in nutrient broth. 1. On agar, the indicator culture traveled more quickly over the agar surface than the phage-carrying strain; the total extent of spread was greater. 2. In broth, the indicator strain grew diffusely throughout the liquid, the lysogenic cells in clumps. The virus-infected strain appeared to grow more slowly. This may reflect (a) the effect of aggregation on the generation time of the lysogenic strain, (b) an active lytic process in the lysogenic population which is further enhanced by the effect of clump formation on the environment of the cell.

Electron Microscopic Observations on Actinophages for Streptomyces venezuelae

Painter , B. G. (University of Minnesota, Minneapolis), and S. G. Bradley . Electron microscopic observations on actinophages for Streptomyces venezuelae . J. Bacteriol. 89: 240–244. 1965.—Actinophages MSP2 and MSP8 were treated with various chemical agents to determine the phages' substructure. Normal MSP2 and MSP8, shadowed with uranium, or negatively stained with uranyl acetate or phosphotungstic acid, were tadpole-shaped. The average overall length of MSP2 was 245 mμ, and of MSP8, 206 mμ. The head width of both phages was approximately 58 mμ; the tail of MSP2 was 161 mμ long, and of MSP8, 137 mμ. Treatment of MSP2 and MSP8 with 7.5 m ammonium hydroxide at 56 C or 8 m urea at room temperature released some of the head contents, and revealed substructures in both the heads and the tails. The tails of phages treated with 7.5 m mercaptoethanol were destroyed.

Electron microscope study of the multiplication of the actinophage affecting Streptomyces griseus

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