Meet Sem Smetsers our microbiologist

At Intrahorti, everything revolves around a healthy foundation for the production of crops. Behind the scenes, microbiologist Sem Smetsers plays a crucial role in the invisible work that supports the healthy growth: by analysing microorganisms in water samples from growers. “You often only see pathogens when it’s already too late. Our analyses help growers stay ahead of problems.”

From Golfcourse to Intrahorti

Twenty-four-year-old Sem Smetsers works since a year as a microbiologist at Intrahorti. His fascination with biology started early, spending much of his childhood outdoors in nature. After completing his Life Sciences degree at HAN University of Applied Sciences in Nijmegen, with a minor in medical microbiology and a specialisation in biomedical research, he interned at a hospital where he came in contact with his favourite bacteria Pseudomonas aeruginosa, a pathogen known for its unmistakable smell.

His second internship led him to Intrahorti, thanks to a chance encounter with the company’s director, Jan van Geest, while Sem was working in hospitality at a local golf course. “Jan started chatting with me, and that’s how I ended up here,” Sem explains. His assignment focused on further developing a qPCR test for detecting Fusarium, a well-known pathogenic fungus among growers.

Making microorganisms visible

Today, Sem is an integral part of the lab team as manager for Microbiological laboratory at Intrahorti. His work is varied: quality control, supporting product development, regulatory documentation, and most notably, analysing water samples for the horticulture sector. “We collect samples from across the grower's system and map out the microorganisms present,” he says. “That provides insight into microbial balance, which is essential for healthy crops.”

These insights are not just for reporting, they directly support the effective use of Intrahorti’s solutions, such as Intra Hydropure. This product is widely used for cleaning and disinfecting water systems, and Sem’s analyses help growers understand when and how to apply it most effectively. “If we see high microbial loads or the presence of specific pathogens, we can recommend targeted interventions with Intra Hydropure to restore water hygiene and protect plant health,” Sem explains.

What does he enjoy most about his work? “The diversity. Every day is different. And the thing is with microorganisms, they are not predictable.”

From agar plates to DNA-profiles

At Intrahorti, both traditional and modern analysis methods are used. “We culture bacteria and fungi on agar plates to determine colony-forming units (CFU/ml), which indicates the quality of the water samples. Additionally, we use qPCR techniques to identify specific pathogens,” Sem explains. These molecular diagnostics are continuously expanding, with the aim of being able to detect the widest possible range of (plant) pathogens in the future . “This allows us to offer even more targeted and timely support to growers.”

One of his favourite organisms in the agriculture is Trichoderma, a beneficial fungus that supports plant health. “It creates beautiful patterns on an agar plate. It's amazing to see how microorganisms can work together to promote healthy growth.”

Important know-how for microorganisms

What should growers know about microorganisms in their water systems? Sem shares three key takeaways:

• Watch the temperature: “In summer, water in the system can heat up quickly. Bacteria and fungi thrive and multiply much faster at temperatures above 20°C. Prevent overheating by flushing your system more frequently.”

• Break the fungal life cycle: “Fungal spores are incredibly resilient and can survive even for years, waiting for the perfect circumstances to regrow to adult fungus. For disinfectants it is easier to eliminate the mycelium of the fungus compared to the spores. That’s why we recommend a frequent use of Intra Hydropure.”

• Work preventively: “Responding only after symptoms appear means you're already behind. Regular water analyses for example help detect issues before they become visible.”

Antibiotic resistance: A global threat

When we ask Sem what is the biggest concern or hot-topic in microbiology, Sem emphasises the risk of resistant bacteria an fungus. “Antibiotic resistance is a huge global issue. Take MRSA for examples, these type of S. aureus strains are no longer susceptible to commonly used first-line antibiotics. With global travel, these strains can easily spread worldwide. In the Netherlands, significant progress has been made in reducing antibiotic use, and Intracare plays an active role in that with its antibiotic-free solutions for livestock.

Sem’s final message

Sem’s final message to growers: “Prevention is better than cure. And being ‘too clean’ is a myth. Microorganisms are everywhere, and that’s okay. What matters is maintaining the right balance between beneficial and harmful organisms.”

Curious about what’s living in your water system?

Intrahorti’s microbial analyses can help you gain insight and stay one step ahead. Contact us for more information.