The laundry chemicals manufacturer purchased the remaining 50% stake for an undisclosed amount to become the sole owner of the food hygiene specialist.
Christeyns bought the remaining shares from outgoing managing director and founder John Bell who retires in March.
Bell said: “I am a little sad but immensely proud to be handing the reins over to Christeyns who have become true friends as well as business partners since we first met, but the time has come for me to take things a little easier."
Plans for Klenzan
Klenzan is a manufacturer of industrial hygiene tools in the UK with expertise in detergent and disinfectant manufacture.
The firm uses chemistry and industry insight to manufacture, design, install and maintain cleaning across the food, brewing and beverage, dairy and pharmaceutical industries.
Christeyns UK purchased an initial stake in Klenzan in 2012.
Alain Bostoen, Christeyns CEO, said it was the right time to bring Klenzan into the Christeyns family and take the company into its next stage of development.
"Developing our presence in the food hygiene industry is a key strategic focus and dovetails with our European aspirations and plans. We are really excited about working with the Klenzan team and helping develop their extensive product range.”
Warmer climate equals more pests
Meanwhile, Rentokil Initial has acquired Allgood Services of Georgia, Inc (trading as Allgood Pest Solutions), a pest control company headquartered in Atlanta, Georgia with operations in Tennessee.
It generated annualised revenues for the 12 months prior to the acquisition of $26m.
The deal does not include Allgood Services, Inc. based in Dublin, Georgia, and operates under the Allgood Pest Solutions brand, outside of the Atlanta market.
Andy Ransom, chief executive of Rentokil Initial, said Allgood has a reputation for service and customer retention levels.
“The acquisition is designed to build scale and customer density in the states of Georgia and Tennessee where the warmer climate means a higher pest intensity,” he said.
“In 2016 we acquired 41 businesses, primarily in our growth and emerging markets, and our pipeline of acquisitions remains particularly strong.”
Rentokil Initial bought 17 businesses in North America last year to accelerate growth in its pest control business and to pursue acquisitions in higher growth markets.
The pest control market in North America is estimated to be worth just over $8bn per annum and accounts for c.50% of the market worldwide.
In 2017, the company has acquired five businesses in the UK and Ireland, Australia and Singapore (four in pest control and one in property care) with combined annual revenues of £15m.