Janibacter hoylei is a species of Gram positive, aerobic, bacterium.

[1] The species was initially isolated from cryovials that sampled high altitude air between 20 and 41 km above sea level.

The optimum growth temperature for J. hoylei is 25-30 °C, and can grow in the 20-40 °C range.

The optimum pH is 9.0, and can grow at 5.0-10.0.

The species is more resistant to UV radiation than other members of Janibacter.