Isolation of bacteriophages from air using vacuum filtration technique: an improved and novel method

Development of a simple and economical air sampler for isolation and enrichment of bacteriophages from air samples.

A vacuum filtration unit with simple modifications was used for isolation of bacteriophages from air sampled in the lavatory. Air was sampled at the rate of 62 l min^-1 by bubbling into Mcllvaine buffer for 30 min, which was used as bacteriophage solution for enrichment and plaque assessment against individual hosts. Alternatively, the aforementioned phage solution was enriched using a host consortium before plaque assessment. Phages were isolated in the range of 1-12 PFU per ml by the first method, whereas enrichment with host consortium gave phages around 10- to 1000-folds higher in number. Combining with established enrichment method, an improvement of about 10 times in phage isolation efficiency was attained.

The method is very useful for studying the natural bacteriophages of air, requiring only a basic microbiological laboratory setup making it simple and economical.

This study brings out a simple, economical air sampler for assessing air bacteriophages that can be employed by any microbial laboratory. Although various methods are available for studying bacteriophages in water and soil, very limited are available for air. To the best of our knowledge, the method developed in this study is unique in its design and concept for studying bacteriophages in air. The sampler is sterilizable by autoclaving and maintains a healthy rate of airflow provided by conventional vacuum pumps. The use of a nonspecific 'trapping solution' allows for the qualitative and quantitative study of air bacteriophages.