All bacteria have their own optimum environmental surroundings and temperatures in which they thrive. Many factors are responsible for a given organism's optimal temperature range, but evidence suggests that the expression of particular genetic elements (alleles) can alter the temperature-sensitive phenotype of the organism. A study published in 2016 demonstrated that mesophilic bacteria could be genetically engineered to express certain alleles from psychrophilic bacteria, consequently shifting the restrictive temperature range of the mesophilic bacteria to closely match that of the psychrophilic bacteria.