Julian Ihssen, a microbiologist and senior lab manager at NEMIS, has spent much of his career pioneering methods to detect and manage pathogenic bacteria. With a PhD from ETH Zurich and years of experience at Biosynth AG and NEMIS, Ihssen has significantly contributed to the development of AquaSpark technology, a luminogenic detection system for E. coli and other pathogenic bacteria. His work is at the forefront of ensuring food safety, particularly through innovative testing methods that enhance our understanding and management of E. coli, Listeria monocytogenes and Salmonella contamination.

The evolution of E. coli detection 

In a recent interview Ihssen delved into the history and significance of E. coli as both a scientific subject and a public health concern. “E. coli was first isolated in 1885 by Theodor Escherich,” Ihssen explained. “It’s a Gram-negative bacterium well-adapted to its hosts, primarily humans and other mammals, and it can grow rapidly under the right conditions, sometimes doubling in as little as 21 minutes.”

E. coli’s ability to adapt to various stressors and its rapid growth rate make it an ideal candidate for laboratory studies and practical applications in food safety. “In my PhD thesis,” Ihssen recounted. “I focused on how E. coli adapts to low nutrient concentrations, revealing its flexibility and resilience.” 

Pathogenic vs. commensal E. coli 

E. coli is not inherently harmful; in fact, it’s a normal part of the human gut microbiome. However, certain strains can be pathogenic. “There are several pathogenic strains of E. coli,” Ihssen noted, “including Uropathogenic (UPEC), Enteroaggregative (EAEC), Enterotoxigenic (ETEC), and the most dangerous, Enterohemorrhagic E. coli (EHEC). These strains can cause severe foodborne illnesses and outbreaks.”  

The challenge in food safety lies in safeguarding final products from contamination with such pathogenic bacteria. Ihssen highlighted the value of advanced E. coli detection methods for identifying pathogen risks in food plants, noting that “standard methods such as the Enterobacteriacaea test might not always be specific enough.” 

Advances in detection technology 

Ihssen’s work at NEMIS focuses on developing easy-to-use, on-site pathogen detection methods. The AquaSpark technology used by NEMIS is based on proprietary, luminogenic substrates for enzymes.  The light signals generated by the enzyme reaction can easily be measured with very high sensitivity. “For E. coli detection our technology leverages the enzyme beta-glucuronidase, present in 99 percent of strains,” he explained. 

This method offers several advantages over traditional techniques. “It’s quick, sensitive, and can detect even low levels of E. coli in various samples,” Ihssen said. “We have validated this technology extensively, showing that it can reliably detect single-digit dried E. coli cells picked up from stainless steel in as little as 16 hours.” 

Applications and regulatory insights 

E. coli detection is vital across multiple sectors, including water and food safety. “In the water sector, the absence of viable E. coli is a key indicator of potable water,” Ihssen stated. “In the food industry, regulations are less strict. For instance, in Switzerland, different thresholds for E. coli presence are allowed in various food products, ranging from 230 CFU per 100 g in seafood to 1000 CFU per gram in some ready-to-eat foods.” 

Ihssen emphasized the importance of E. coli as a hygiene indicator. “E. coli does not multiply outside its host environment,” he said. “This makes it a reliable indicator of recent fecal contamination, which can also point to the presence of other pathogens transmitted via the fecal-oral route.” 

The future of E. coli detection 

Looking ahead, Ihssen sees potential for even greater advancements in detection technology. “We are continuously improving the sensitivity and usability of our assays,” he remarked. “Our goal is to make these tests accessible to more industries, ensuring that food safety protocols can be upheld with minimal hassle.”  

He also noted the importance of addressing antibiotic resistance. “Some E. coli strains produce enzymes like ESBL and carbapenemase, which degrade almost all modern antibiotics,” Ihssen warned. “Our detection method could be adapted for quickly identifying these strains, providing crucial data for managing outbreaks and treatment strategies.” 

Final thoughts 

Julian Ihssen’s contributions to microbiology and biotechnology, particularly in the realm of pathogen detection, underscore the vital role of scientific innovation in public health. His work with AquaSpark and other technologies at NEMIS exemplifies the ongoing efforts to enhance food safety and protect consumers from foodborne illnesses. 

“As we continue to refine our methods and expand their applications, we are optimistic about the future of food safety,” Ihssen concluded. “Advanced detection systems like ours are crucial in the fight against pathogenic bacteria, ensuring safer food and water for everyone.”