Water & Wastewater Asia Jul/Aug 2018

WATER & WASTEWATER ASIA July / August 2018 I n the early 1980s, when culture growth i n l abora tor y t es t tubes and petri dishes were considered the rule, Professor Rita R. Colwell’s laboratory discovered and demonstrated that bacteria can exist in a dormant state in which they are alive and can cause harm even though they cannot be cultured. She coined the term “viable but non- cultural” (VBNC) to describe this phenomenon. This discovery, in Professor Colwell’s words, “of course, was very contentious at the time” but ultimately proved the inadequacy of traditional culture-based methods in determining water safety. Professor Colwell is the recipient of the prestigious Lee Kuan Yew Water Prize 2018 in recognition of her discoveries and innovations in water science which have fundamentally changed the world’s understanding of water microbiology. Water and Wastewater Asia talks to 83-year-old Professor Colwell (PC) in the second part of our interview to find out more about VBNC, how she discovered saris can help curb the spread of the Vibrio cholerae pathogen, widely known as cholera and how the bioterrorism attack using Anthrax in 2001 eventually led to her invention of rapid diagnostic technology to identify different strains of bacteria. Q What is the VBNC phenomenon and how was it discovered? PC: The VBNC phenomenon represents the set of changes in properties of bacteria that occur when conditions are not optimum for growth and cell division. The bacteria essentially change their morphology and enter a dormant state, remaining thus until conditions improve for cell growth and division. We discovered VBNC bacteria late in the 1970s and early 1980s, about 35 years ago. Our discovery, of course, was very contentious at the time, because culture growth in laboratory test tubes and petri dishes was considered the rule. Q What kind of resistance did you face after making your discovery known? PC: Resistance against the discovery of VBNC was predominantly from the medical community and not so much the environmental microbiologists who first learnt in the early 60s that sea water, for example, contained “ultra-microbiota” -- very tiny bacteria that would pass through a .2 µm filter device. It was believed by the medical community that if bacteria did not grow in the laboratory and even if those bacteria could be detected by using a variety of molecular techniques, that they must be dead. We were able to dispute this by showing that cholera toxin continued to be produced by the viable but non- cultured chloera bacteria. But sad to say, even that was insufficient at that time of our very early work. 63 9 - 11 JULY 2018

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