Alcaligenes viscolactis

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Bar: 5 µm. Image credit: SCIMAT.

Classification

Bacteria; Pseudomonadota; Betaproteobacteria; Burkholderiales; Alcaligenaceae

Species

NCBI: [1]

Alcaligenes viscolactis

Description and Significance

Alcaligenes viscolactis is a (harmless) bacteria found in dairy products, most commonly milk, that causes it to have a "ropey" consistency. It thrives in environments with temperatures around 21°C, making it essential to monitor storage temperatures of dairy.

Genome Structure

This bacteria has only been partially sequenced with 345 known base pairs and is assumed to have a circular genome the rest of the bacteria in the genus Alcaligenes.

Cell Structure, Metabolism and Life Cycle

The Alcaligenes viscolactis has a very short and round rod shape that is classified as Coccus. Its diameter ranges from 0.5 to 1.0 µm and its length ranges from 0.5 to 2.6 µm. The microbe is gram-negative, non-motile, and unpigmented.

The metabolism of A. viscolactis is primarily chemoorganotrophic, meaning it derives energy from organic compounds. It exhibits a versatile metabolic profile, capable of utilizing a range of carbohydrates, amino acids, and organic acids as carbon and energy sources. Notably, it produces extracellular polysaccharides (EPS), which contribute to its ability to form biofilms and promote survival in nutrient-poor or competitive environments. The bacterium operates predominantly through aerobic respiration, utilizing oxygen as the terminal electron acceptor. It possesses key enzymes like oxidases and catalases, enabling efficient energy production while protecting against oxidative stress. In the absence of oxygen, A. viscolactis can switch to fermentative pathways, albeit less efficiently, allowing survival in microaerophilic or anaerobic conditions. Metabolically, A. viscolactis plays roles in biotechnological applications, including bioremediation, due to its ability to degrade complex compounds, such as hydrocarbons and aromatic substances.

The life cycle of A. viscolactis is straightforward and involves binary fission for reproduction. Under optimal environmental conditions, including a temperature range of 20–37°C and neutral pH, the bacterium rapidly divides. During binary fission, DNA replication precedes the partitioning of the cell, leading to the formation of two genetically identical daughter cells. Biofilm formation is a significant phase of its life cycle, providing a communal living strategy that enhances resistance to environmental stresses and promotes persistence on surfaces. In nutrient-rich environments, it grows planktonically, while in nutrient-limited conditions, biofilm formation is favored.

Ecology and Pathogenesis

Found in aqueous environments, it is nonmotile, aerobic, and a gram-negative rod. It is typically found in soil, water, and in the intestinal tract of some animals. It has been found in milk and is the bacteria that causes milk to become ropy.

This bacterium has potential use as a inhibitor of various pathogenic organisms due to there being no record of its pathogenicity, opportunistic or otherwise. It has been found to inhibit S. Aureus and C. Albicans, by a microbicidal, contact-dependent mechanism

References

Edmiston C. E., Fassel T.A., Toddar K. (2011). Alcaligenes viscolactis. SCIMAT.

Feng, Y., Zhang, C., Li, W. (2023). Metagenomic insights into the functional diversity and metabolic pathways of Alcaligenes species in wastewater treatment. Journal of Microbiological Research. 12(5): 347-359.

Fuqua, Andrew. (2020). Characterization of the Broad-spectrum Inhibitory Capabilities of Alcaligenes faecalis and A. viscolactis against Potential Pathogenic Microorganisms. Digital Commons @ East Tennessee State University. Undergraduate Honors Thesis. 546.

Martin J. H., Su Chung K. S., Grosky L. (1972). Inhibition of Growth of Alcaligenes viscolactis by Some Common Food Preservatives. Journal of Dairy Science. 55(8): 1179-1181.

Punch J. D., Olsen Jr. J. C., Scaletti J.V. (1956). Amino Acid Utilization by Alcaligenes viscolactis for Growth and Slime Production. National Library of Medicine. National Center for Biotechnology Information. 89(6): 1521-1525.

Williams K. P. (2016). Alcaligenes viscolactis S-2 tmRNA (ssrA) gene, partial sequence. National Library of Medicine. National Center for Biotechnology Information. Genbank: AY911519.1.

Willems, R. J. L., and van Schaik, H. (2019). Transition of Enterococci from commensal organisms to leading causes of multidrug-resistant infections in the healthcare setting. Clinical Microbiology and Infection. Volume 25(7): 955-963.

Author

Page authored by Leigha Boyd, Dyan-jashly Carino, Sydney Dowtin, & Abigal Smith, students of Prof. Bradley Tolar at UNC Wilmington.