Lactococcus chungangensis
A Microbial Biorealm page on the genus Lactococcus chungangensis
Classification
Higher order taxa
Bacteria; Firmicutes; Bacilli; Lactobacillales; Streptococcaceae; ‘’Lactococcus’’; ‘’chungangensis’’ (NCBI: http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=1122154)
Species
Lactococcus chungangensis
Description and significance
Lactococcus chungangensis is a gram-positive, coccoid, aerobic and facultatively anaerobic, psychrotolerant, non-motile prokaryote. This species has been recently identified, from being isolated in activated sludge foam in a wastewater treatment plant in Korea[1]. This strain is known as CAU28T. They also produce some products that serve to enhance flavor in cheese, by a variety of genes that code for certain enzymes. This particular species has been analyzed for differences in genetic material from L. lactis. It was found to have the highest uptake of alcohol, by alcohol dehydrogenase (ADH), of any species in the genus[4].
L. chungangensis is important for industrial cheese production, as it may be responsible for distinct flavors that other species of the genus’ lack due to certain genes either up or down regulated. It also may show a benefit due to its alcohol uptake by alcohol dehydrogenase (ADH) activity. It was shown to reduce alcohol uptake in mouse serum. Casein degradation is the major precursor to flavor in cheese production[3].
Genome structure
The genome is 40% G-C. There are several sequences ranging from 390-751 bp linear DNA of various configs or fragments that have been amplified for analysis. 16s rRNA sequencing shows 1,463 bp linear RNA. Full sequencing of this genome has not been completed.
It is known that 415 genes are upregulated, and 1,500 were downregulated when compared to L. lactis, of the 1,915 probes performed. Two important genes that are upregulated include genes controlling aminohydrolase and S-adenosylmethionine, which are important flavor enzymes in cheese production[3].
Cell and colony structure
L. chungangensis is a coccoid and sometimes ovoid shaped cell. It appears as single cells, pairs, short chains and irregular clusters of varying number. Cells are non-motile. The cells were not observed to form spores or mycelium. Colonies appear white and opaque[1].
Metabolism
The metabolism pathway of the whole Lactoccus genus is fermentation, specifically homofermentation of milk. This process is important because it participates in the rapid acidification of milk, which prevents the growth of spoilage bacteria.
The energy sources of L. chungangensis are amygdalin, maltose, and sucrose and a number of variations of each (D-glucose, D-fructose, D-mannose, mannitol, N-acetylglucosamine, amygdalin, arbutin, salicin, maltose, sucrose, and gentiobiose). The butanediol pathway is used; as the organism is VP positive[1]. These sugars are its sole source of carbon. It is classified as facultatively anaerobic.
Important molecules that L. chungangensis produces are leucine aminopeptidase, which breaks down proteins. A unique CRISPR cas sequence has been patented by DuPont that involves L. chungangensis ability to resist attacks by phages[5].
Ecology
Its habitat is only known in active sludge foam of a water treatment plant, but it is thought that the bacterium entered this habitat as a waste from metabolism of dairy. It is postulated that in the dairy habitat include flavor enhancement, as well as removal of alcohol from other fermenting bacterium. L. chungangensis CAU28T grows at 4°C, but not 40°C[1].
Metagenomic Data: http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?lvl=0&id=11221546
Pathology
Lactococcus chungangensis is likely non-pathogenic, unless as an opportunative pathogen, as is the case with L. lactis2. There are no studies reporting any animal or plant hosts, or any virulence factors.
References
[1]. Cho, SL et al.Lactococcus chungangensis sp. nov., a lactic acid bacterium isolated from active sludge foam.” International Journal of Systematic and Evolutionary Microbiology (2008), 58, 1844-1849. DOI 10.1099/ijs.0.65527-0.
[2]. Facklam, Richard and J.A. Elliott. “Identification, Classification, and Clinical Relevance of Catalase-Negative, Gram-Positive Cocci, Excluding the Streptococci and Enterococci.” Clincal Microbiology Reviews (1995) Vol. 8, No. 4. 481-482. DOI 0893-8512/95/
[3]. Konkit, M et al. “Transcriptomic analysis of Lactococcus chungangensis sp. nov. and its potential in cheese making.” Journal of Dairy Science (2014), 97, 7362-7372. DOI 10.3168/jds.2014-8299.
[4]. Konkit, M et al. “Alcohol dehydrogenase activity in Lactococcus chungangensis: Application in cream cheese to moderate alcohol uptake.” Journal of Dairy Science (2015) 98, 5974-5982. DOI 10.3168/jds.2015- 9697.
[5] Horvath, et al. "Lactococcus crispr-cas sequences". Dupont Nutrition Biosciences Aps. Patent #: US 20130288251 A1. 2013.
[6]“Lactococcus chungangensis CAU 28 = DSM 22330.” NCBI. Web. [Accessed 10/30/15].
Page created by Joshua Browning with Dr. Lisa R. Moore, University of Southern Maine, Department of Biological Sciences, http://www.usm.maine.edu/bio
