Nonlabens ulvanivorans

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A Microbial Biorealm page on the genus Nonlabens ulvanivorans

Classification

Higher order taxa

Domain: Bacteria;
Phylum: Bacteriodetes;
Class: Flavobacteria;
Order: Flavobacteriales;
Family: Flavobacteriaceae

NCBI: [1]

Species

Nonlabens ulvanivorans

Description and significance

Nonlabens ulvanivorans stains gram-negative and is a peach-colored, rod-shaped, non-gliding, strictly aerobic, chemo-organotroph originally isolated from the feces of the mollusk Aplasia punctate at Presqu'île de Pen Lan, Pleubian, Brittany, France in 2011 [1]. N.ulvanivorans is considered novel for its ability to degrade and metabolize ulvan, an essential polysaccharide component of the cell-wall matrix of green seaweeds of the phylum Chlorophyta and order Ulvales [1]. The structure and biological functions of Ulvan are currently the subjects for research the polysaccharide's potential in products of therapeutic, nutraceutical, and personal care value [1]. Thus, understanding the mechanisms by which N. ulvanivorans breaks down and ultimately metabolizes Ulvan is of economic value for the exploitation of the complex polysaccharide.
Nonlabens ulvanivorans was originally classified as Persicivirga ulvanivorans, this classification that was challenged and corrected in 2012 by a cross-analysis of the 16S rRNA of four genuses: Nonlabens, Persicivirga, Stenothermobacter, and Sandarakinotalea. It was concluded that the Nonlabens genus was most descriptive of the species in question [3].

Genome structure

The genome has a length of 3,220,243 base pairs. There are 2,954 coding sequences, 1,752 code for annotated functions while the remaining 1,202 are for hypothetical proteins. There are also 21 tRNA genes and 1 rRNA operon, which is consistent with the estimated number of rRNA functions for the Flavobacteriacease family. The significance of the first draft genome sequence for N. ulvanivorans is to understand which enzymes enable the bacteria to degrade Ulvan and how the polysaccharide is metabolized. [2]

Cell and Colony Structure

Cells are gram-negative rods generally 1 µm in diameter and 1.5-5.5 µm in length that occur in pairs or singly. N. ulvanivorans cells are non-flagellated and do not display motility on solid surfaces. In the primary research, circular, shiny, orange/red colonies grew to 2.0-3.0 mm in diameter after 5 days of incubation on ZoBell agar plates. Spreading did not occur at the margin of the colonies [1].

Metabolism and Unique Enzymes

N.ulvanivorans can oxidatively metabolize a variety of simple saccharides in strictly aerobic conditions and uses Oxygen as the electron acceptor; it cannot use Nitrogen as an electron acceptor. N.ulvanivorans is most unique for its ability to cleave, degrade, and metabolize the polysaccharide cell wall of green seaweeds through a suite of unique polysaccharide-lyse enzymes [1]. In the partial sequencing of the genome, a known ulvan-cleaving and oligosaccharide-degesting enzyme (β-glucuronyl hyrdolyase) was located near the novel ulvan-degrading lyase [2]. The novel ulvan lyase depolymerizes the complex ulvan structure into simpler sugars which are then subjected to further degradation by β-glucuronyl hyrdolyase and, as of yet, other undescribed enzymes.

Ecology

The original N.ulvanivorans sample was extracted from the feces of the sea slug A. punctate, which feeds primarily on seaweeds of the Ulva genus, suggesting that N.ulvanivorans inhabits the digestive tract of this mollusk providing symbiotic aide in the degradation and digestion of the polysaccharide Ulvan. In the laboratory setting, optimum growth occurred at a temperature is 25°C, and no growth occurred at 37°C after 8 days. For pH, N. ulvanivorans succeeds between 7.5 and 8.0, with no growth detected below 6.0 or above 10.0. Optimum NaCl concentrations are between 2.0 – 50 g/l, with preference for 25 g/l; no growth occurs in the absence of NaCl or in concentrations greater than 6.5% [1].

Pathology

N. ulvanivorans is resistant to a number of antibiotics, including: streptomycin, tetracycline, chloramphenicol, kanamycin, getnamicin, fosfomycin, colistin, and nalidixic acid. However, growth is inhibited by penicillin, ampicillin, carbenicillin, rifampicin, cefalotin, cefoxitin, cefotaxim, imipenem, and meropenem [1]. There are no documented cases of infection and human, but it can be suspected that N. ulvanivorans is an opportunistic pathogen like its Flavobacteriaceae relatives.

References

[1] Barbeyron, Tristan, et al. “Persicivirga ulvanivorans sp. nov., a marine member of the family Flavobacteriaceae that degrades ulvan from green algae.” International Journal of Systematic and Evolutionary Microbiology (2011), 61, 1899–1905.

[2] Kopal, Moran, et al. “Draft Genome Sequence of Nonlabens ulvanivorans, an Ulvan-Degrading Bacterium.” Genome Announcements. American Society for Microbiology. July/August 2014 Vol. 2 No. 4 e00793-14.

[3] Yi, Hana et al. “Unification of the genera Nonlabens, Persicivirga, Sandarakinotalea and Stenothermobacter into a single emended genus, Nonlabens, and description of Nonlabens agnitus sp. nov.” Systematic and Applied Microbiology. Vol. 35. Issue 3. P. 150-155.

Edited by Connor McKay of Dr. Lisa R. Moore, University of Southern Maine, Department of Biological Sciences, http://www.usm.maine.edu/bio