Martin George. Dying of the Light

Haviland Tuf is an honest space-trader who likes cats. So how is it that, in competition with the worst villains the universe has to offer, he’s become the proud owner of the last seedship of Earth’s legendary Ecological Engineering Corps? Never mind, just be thankful that the most powerful weapon in human space is in good hands-hands which now control cellular material for thousands of outlandish creatures.
With his unique equipment, Tuf is set to tackle the problems human settlers have created in colonizing far-flung worlds: hosts of hostile monsters, a population hooked on procreation, a dictator who unleashes plagues to get his own way…and in every case the only thing that stands between the colonists and disaster is Tuf’s ingenuity-and his reputation as an honest dealer in a universe of rogues…