# Vibrio natriegens

Vibrio natriegens is a Gram-negative marine bacterium. It was first isolated from salt marsh mud. It is a salt-loving organism (halophile) requiring about 2% NaCl for growth. It reacts well to the presence of sodium ions which appear to stimulate growth in Vibrio species, to stabilise the cell membrane, and to affect sodium-dependent transport and mobility. Under optimum conditions, and all nutrients provided, the doubling time of V. natriegens can be less than 10 minutes. V. natriegens is able to successfully live and rapidly divide in its coastal areas due its large range of metabolic fuel. Recent research has displayed that Vibrio natriegens has a flexible metabolism, which allows it to consume a large variety of carbon substrates, reduce nitrates, and even fix nitrogen from the atmosphere under nitrogen-limiting and anaerobic conditions. In the laboratory, the growth medium can be easily changed, thus affecting the growth rate of a culture. V. natriegens is commonly found in estuarine mud.

## Aquaculture and antibiotic resistance

Many strains of Vibrio, including natriegens, are pathogenic against farmed aquacultures such as the abalone and have recently resulted in destruction of farmed abalones when aquacultures get infected. In response, fishers have taken to inoculating tanks with large amounts of antibiotics, which has resulted in Vibrio natriegens developing a potent antibiotic resistance to many drugs. In a recent study, the AbY-1805 strain of Vibrio natriegens was shown to be completely resistant against 17 of the 32 tested antibiotics and at least partially resistant against 22 of the 32.

## Biochemical characteristics of V. natriegens

Colony, morphological, physiological, and biochemical characteristics of Vibrio natriegens are shown in the Table below.
| Test type | Test | Characteristics |
| Colony characters | Size | Medium |
| Colony characters | Type | Round |
| Colony characters | Color | Whitish |
| Colony characters | Shape | Convex |
| Morphological characters | Shape | Vibrio |
| Physiological characters | Motility | + |
| Physiological characters | Growth at 6.5% NaCl | + |
| Biochemical characters | Gram's staining | – |
| Biochemical characters | Oxidase | + |
| Biochemical characters | Catalase | + |
| Biochemical characters | Oxidative-Fermentative | Oxidative |
| Biochemical characters | Motility | + |
| Biochemical characters | Methyl Red | – |
| Biochemical characters | Voges-Proskauer | – |
| Biochemical characters | Indole | – |
| Biochemical characters | H$_2$S Production | + |
| Biochemical characters | Urease | + |
| Biochemical characters | Nitrate reductase | + |
| Biochemical characters | β-Galactosidase | + |
| Hydrolysis of | Gelatin | + |
| Hydrolysis of | Aesculin | + |
| Hydrolysis of | Casein | + |
| Hydrolysis of | Tween 40 | + |
| Hydrolysis of | Tween 60 | + |
| Hydrolysis of | Tween 80 | + |
| Acid production from | Glycerol | + |
| Acid production from | Galactose | + |
| Acid production from | D-Glucose | + |
| Acid production from | D-Fructose | V |
| Acid production from | D-Mannose | V |
| Acid production from | Mannitol | V |
| Acid production from | N-Acetylglucosamine | + |
| Acid production from | Amygdalin | – |
| Acid production from | Maltose | + |
| Acid production from | D-Melibiose | – |
| Acid production from | D-Trehalose | – |
| Acid production from | Glycogen | + |
| Acid production from | D-Turanose | + |
Note: + = Positive, – =Negative, V =Variable (+/–)

## Biotechnological uses

Owing to its rapid growth rate, ability to grow on inexpensive carbon sources, and capacity to secrete proteins into the growth media, efforts are underway to leverage this species as a host for molecular biology and biotechnology applications. Recently, V. natriegens crude extract has been shown by multiple research groups to be a promising platform for cell-free expression. Scientists are also hoping that Vibrio natriegens, with its incredible growth speed, will make microbial experiments in outer space, where time is an extremely valuable asset, much quicker. Interestingly, it has been shown that Vibrio natriegens, despite its incredibly quick doubling speed on Earth, might grow even faster in space. A recent experiment displayed that after 24 hours of growth the Vibrio cells grown in zero gravity were 60 times denser than those grown in full gravity, possibly attributable to an extended exponential growth phase in low-gravity conditions.