Treatment Plant Operator’s Bug of the Month is an ongoing series that spotlights the organisms present in wastewater microbiology. Each month a new organism is featured, giving readers a profile of the species and how it functions in a wastewater treatment setting. 

In this peek under the microscope, take an up-close look at Hyphomicrobium.

Hyphomicrobium are a genus within the Proteobacteria phylum. Over 30 individual species of Hyphomicrobium have been identified (Nierychlo, M. 2019). Hyphomicrobium can be easily identified at 1000x phase contrast oil immersion due to their “bean on a stalk” (skinny with a tip) morphology. The “stalks” are very thin and typically < 0.3 µm in diameter. It is fairly common to see the stalk only without the tip. Hyphomicrobium are non-filamentous bacteria, and only in very rare instances are they believed to impact the settling properties of the sludge.

A C1 compound buffet

Hyphomicrobium utilize single carbon compounds such as methanol and methylamine for growth. These C1 compounds may be naturally occurring in the influents of many industrial wastewater processes as a production byproduct, or can be formed in areas of deep fermentation such as collection systems, lift stations and septic primary clarifiers. Many species of Hyphomicrobium are capable of denitrification, and these are often observed in facilities dosing methanol as a carbon supplement for biological nutrient removal.

In wastewater microbiology the term “you are what you eat” applies to which organisms compete. In facilities that do not have known C1 compounds from industrial processes or supplement methanol for nutrient removal, the presence of Hyphomicrobium at significant abundance (common or higher) suggests septicity/fermentation of the wastewater at some point in the process. Further observation and identification of the surrounding filamentous morphotypes and indicator organisms and their associated cause(s) is needed to help confirm the overall conditions present. 

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About the author: Ryan Hennessy is the microbiology and operations specialist at Midwest Contract Operations Inc. He was trained and mentored by Dr. Michael Richard for over 10 years in wastewater microbiology, and serves as a microbiology services consultant. Hennessy is a licensed wastewater treatment and municipal waterworks operator in the state of Wisconsin and fills in as needed for operations at several facilities. He can be reached at rhennessy@mco-us.com.