Hypochlorite Stress Assay for Phenotypic Analysis of the Halophilic Archaeon Haloferax volcanii Using an Improved Incubation Method and Growth Monitoring

The study of haloarchaea provides an opportunity to expand understanding of the mechanisms used by extremophiles to thrive in and respond to harsh environments, including hypersaline and oxidative stress conditions. A common strategy used to investigate molecular mechanisms of stress response involves the deletion and/or sitedirected mutagenesis of genes identified through omics studies followed by a comparison of the mutant and wildtype strains for phenotypic differences. The experimental methods used to monitor these differences must be controlled and reproducible. Current methods to examine recovery of halophilic archaea from extreme stress are complicated by extended incubation times, nutrients not typically encountered in the environment, and other related limitations. Here we describe a method for assessing the function of genes during hypochlorite stress in the halophilic archaeon Haloferax volcanii that overcomes these types of limitations. The method was found reproducible and informative in identifying genes needed for H. volcanii to recover from hypochlorite stress.

Automated summary

Studying haloarchaea helps us understand how extremophiles survive and respond to harsh environments. A common strategy is to mutate genes identified through omics studies and compare the mutant strains with wildtype strains to study stress response mechanisms. However, current methods to study recovery from extreme stress have limitations. In this study, a method was developed to overcome these limitations and successfully evaluate the function of genes during hypochlorite stress in the halophilic archaeon Haloferax volcanii.