Empedobacter brevis is a bacterium recognized for its environmental adaptability, inhabiting diverse natural and human-made ecosystems. It belongs to the phylum Bacteroidota. Formerly classified as Flavobacterium breve, its current name reflects a deeper understanding of its genetic and physiological profile. The organism is of interest due to its robust survival mechanisms in harsh environments and its capacity to interact with complex organic and inorganic compounds.
Defining Characteristics
This microorganism is characterized as a Gram-negative bacillus. Morphologically, E. brevis is rod-shaped and generally non-motile. Colony growth on solid media often results in a characteristic yellow pigmentation, a trait shared with other members of its family, the Weeksellaceae, which is part of the class Flavobacteriia.
The bacterium maintains a mesophilic metabolism, thriving within a moderate temperature range, with growth observed between 15°C and 41°C and an optimal temperature around 30°C. Physiologically, E. brevis is an obligate aerobe, requiring oxygen for metabolic processes. Biochemical testing reveals that this species is generally oxidase-negative and catalase-negative, but it is known to hydrolyze gelatin, indicating its capacity to break down proteins.
The organism’s ability to thrive stems from its nutritional versatility. It possesses inherent proteolytic and amylolytic activities, allowing it to break down both proteins and starches in its environment. This metabolic flexibility enables it to utilize a broad spectrum of organic material for sustenance.
Environmental Presence
Empedobacter brevis is a ubiquitous environmental inhabitant, commonly isolated from diverse ecological niches across the globe. Its natural reservoir includes a variety of soil types, freshwater systems, and marine environments. The bacteria are also frequently found associated with plants and raw food products.
Its resilience allows it to colonize environments directly influenced by human activity, including industrial and clinical settings. The organism has been found in pharmaceutical and industrial wastewater streams, surviving in conditions that are toxic to many other species. Furthermore, its presence is notable within hospital water systems, such as sinks, faucets, incubators, and hemodialysis systems.
Bioremediation Capabilities
The organism’s environmental role is pronounced in its capacity for bioremediation, particularly the detoxification of heavy metals and recalcitrant compounds. Studies have demonstrated the ability of E. brevis to degrade methylmercury (CH3Hg+), a highly toxic and persistent pollutant found in industrial waste and leachate. In controlled aerobic experiments, the bacterium achieved a methylmercury reduction efficiency of 81%.
This detoxification is thought to occur through enzymatic pathways that transform the toxic compound into less harmful forms, representing a valuable natural mechanism for environmental cleanup. The organism’s obligate aerobic metabolism suggests that oxygen-dependent enzymes drive the degradation of these complex molecules.
The general metabolic activities of the bacterium, including the breakdown of proteins and starches, are also significant in natural environmental processes. By decomposing large organic molecules, E. brevis contributes to the recycling of nutrients within soil and water ecosystems. Its presence in industrial wastewater suggests a broader ability to process various complex organic chemicals that resist conventional breakdown.
Clinical Interactions
While primarily an environmental bacterium, Empedobacter brevis is recognized in clinical settings as an opportunistic pathogen. It rarely causes disease in healthy individuals but poses a risk to vulnerable patients, particularly those who are immunocompromised or neonates. Its association with infections often involves healthcare environments, classifying it as a nosocomial organism.
The bacterium has been implicated in serious infections, including cases of bacteremia, meningitis, and infections related to indwelling medical devices like ventriculostomy catheters. A concern in clinical management is the organism’s tendency to display multi-drug resistance. This resistance includes a decreased susceptibility to certain antibiotics, such as extended-spectrum cephalosporins and carbapenems. This reduced susceptibility is sometimes linked to the presence of a chromosome-encoded beta-lactamase enzyme, designated blaEBR-1.