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Aim: To evaluate the effect of temperature on growth parameters and on extracellular polymeric substance (EPS) production for Pseudoalteromonas antarctica NF3. Methods and Results: For this purpose, three growth parameters, lag time (λ), maximum growth rate (μ) and maximum population density (A), were calculated with the predictive Gompertz model. To evaluate the variations in μ with respect to temperature, the secondary Arrhenius and the square root models were used. Below the optimal growth temperature (17·5°C), the growth of P. antarctica was separated into two domains at the critical temperature of 12°C. Within the suboptimal domain (12–17·5°C), the temperature characteristic was the lowest (5·29 kcal mol−1). Growth population densities were maintained over the entire physiological portion assayed (5–17·5°C). Higher crude EPS production was found at temperatures included in the cold domain (5–12°C). Conclusions: All calculated parameters revealed an optimal adaptation of this strain to cold temperatures. Significance and Impact of the Study: The knowledge of the influence of temperature on growth parameters of P. antarctica NF3 and on EPS production could improve the production of this extracellular polymeric substance that is currently being used in the cosmetic and pharmaceutical industries.

The psychrotolerant strain Pseudoalteromonas antarctica NF3, a Gram-negative bacterium isolated from muddy soil samples of Antarctica, secretes large amounts of a mucoid exopolymer with a high protein content. It has self-assembly properties and capacity to coat and protect liposomes against surfactants. We examined the ultrastructure of P. antarctica and the extracellular matter it secretes by transmission electron microscopy (TEM) after high-pressure freezing, freeze substitution (HPF-FS), and Epon embedding, and compared this with information obtained by conventional methods. The improvements brought about by HPF-FS to the ultrastructural preservation of the extracellular matter allowed us to establish for the first time, in P. antarctica NF3, the presence of two components: a large amount of cell-derived outer membrane vesicles containing proteins and a capsular polymer around the cells.

The various organisms thriving in extreme environments on Earth, psychrophiles (cold-loving organisms) are the most abundant in terms of biomass, diversity, and distribution. The chapter presents an overview of the biotechnological uses of psychrophiles and of their biomolecules using selected examples. Site-specific mutants of psychrophiles are a useful tool to study cold adaptation and expression of cold-active enzymes at low temperature. At the industrial level, the best-known representative of polar microorganisms is certainly the yeast Candida antarctica, as its species name unambiguously refers to the sampling origin. Antarcticine-NF3 is a glycoprotein with antifreeze properties produced by the bacterium Pseudoalteromonas antarctica, which has been patented by Spanish researchers. It was found that Antarcticine is effective for scar treatment and re-epithelialization of wounds. Most studies on hydrocarbon bioremediation in polar regions have focused on the treatment of petroleum hydrocarbons, since increased petroleum exploration increases the risk of accidental oil release. Polar plants and animals have also found diverse applications and are worth citing in the context of the present survey. Recent developments based on cold-adapted organisms and their biomolecules have clearly demonstrated the huge potential of psychrophiles.

The ability of an exopolymer of glycoproteic character (GP) excreted by a new gram-negative specie, Pseudoalteromonas antarctica NF 3 , to coat phosphatidylcholine (PC) unilamellar liposomes and to protect these bilayer structures against the solubilizing action of the non-ionic surfactant Triton X-100 (T X-100 ) has been investigated. TEM micrographs of freeze fractured liposome/GP aggregates reveal that the presence of GP in liposome suspensions resulted in the formation of a continuous thin film that coated tightly these bilayer structures. The complete coating of these vesicles was already achieved at a PC:GP weight ratio of about 9:1. Higher GP amounts (up to a PC:GP weight ratio of 1:1) led to a progressive growth of this film which exhibited at the highest GP proportion a multilayered structure. An increasing resistance of PC liposomes to be solubilized by T X-100 took place as the proportion of GP in the system rose, although this protective effect was more effective at low GP proportions (PC:GP weight ratios from 9:1 to 4:1). Thus, although in the range of PC:GP weight ratios from 9:1 to 6:4 a direct dependence was found between the growing of the covering structure and the resistance of the coated liposomes to be solubilized by T X-100 , the best protection effect occurred when this covering structure was a thin and continuous film with a thickness not higher than 15–20 nm (PC:GP weight ratios ranging from 9:1 to 4:1).

The ability of an exopolymer of glycoproteic character (GP) excreted by a new Gram-negative species Pseudoalteromonas antarctica NF3, to coat phosphatidylcholine (PC) liposomes and to protect these...

The taxonomic characteristics of five bacterial strains which were isolated from Antarctic coastal marine environments were studied. These bacteria were psychrotrophic, aerobic, and gram negative with polar flagella. The G + C contents of the DNAs of these strains were 41 to 42 mol%. The Antarctic strains were phenotypically distinct from the previously described Pseudoalteromonas type species. DNA-DNA hybridization experiments revealed that the new strains were closely related to each other but clearly different from Pseudoalteromonas haloplanktis and Pseudoalteromonas atlantica, which were the most phenotypically similar organisms. None of the bacterial isolates was capable of using DL-malate, D-sorbitol, or m-hydroxybenzoate, and all were capable of gelatin hydrolysis. Strains NF2, NF3T (T = type strain), NF13, NF14, and EN10 had an Na+ requirement but required only 17 mM Na+. Phenotypic, DNA G + C content, DNA-DNA hybridization, 16S rRNA analysis, fatty acid composition, and protein profile data confirmed the identification of the Antarctic strains as members of a Pseudoalteromonas sp. The name Pseudoalteromonas antarctica sp. nov. is proposed for these organisms.

Pseudoalteromonas antarctica NF3 is an Antarctic psychrotolerant Gram-negative bacterium that accumulates large amounts of an extracellular polymeric substance (EPS) with high protein content. Transmission electron microscopy analysis after high-pressure freezing and freeze substitution (HPF-FS) shows that the EPS is composed of a capsular polymer and large numbers of outer membrane vesicles (OMVs). These vesicles are bilayered structures and predominantly spherical in shape, with an average diameter of 25-70 nm, which is similar to what has been observed in OMVs from other Gram-negative bacteria. Analyses of lipopolysaccharide (LPS), phospholipids and protein profiles of OMVs are consistent with the bacterial outer membrane origin of these vesicles. In an initial attempt to elucidate the functions of OMVs proteins, we conducted a proteomic analysis on 1D SDS-PAGE bands. Those proteins putatively identified match with outer membrane proteins and proteins related to nutrient processing and transport in Gram-negative bacteria. This approach suggests that OMVs present in the EPS from P. antarctica NF3, might function to deliver proteins to the external media, and therefore play an important role in the survival of the bacterium in the extreme Antarctic environment.

The article focuses on regulating bioprospecting activities in Antarctica. A patent and trademark office has yet to open its doors on McMurdo Sound or at Prydz Bay. But the microbes and fish that live in Antarctica and its environs have already become the subject of patent claims. The Spanish patent office granted a patent in 2002 for wound healing and other treatments with a glycoprotein drawn from the bacterium Pseudoalteromonas antarctica. Also that year Germany handed out a patent for a skin treatment using an extract from the green alga Prasiola crispa ssp.antarctica. And an application now before the U.S. Patent and Trademark Office covers a process for producing antifreeze peptides discovered in Antarctic bacteria. In all, it is estimated that more than 40 patents have been granted worldwide that rely on Antarctic flora and fauna, and the U.S. patent office has received in excess of 90 filings. These numbers are not large--and no commercial enterprise is engaged in industrial harvesting of the continent's biota. But drug companies bring in tens of billions of dollars every year from natural compounds or synthetic knockoffs inspired by them. Interest in developing pharmaceuticals from Antarctica's novel life-forms, extremophiles--which withstand cold, aridity and salinity--will continue to grow. Moreover, it is already a problem to figure out who is doing the collecting and for what purpose. Bioprospecting often involves consortia composed of public and private entities. Delineating where scientific research ends and commercial activity begins becomes a difficult task, notes a report from the U.N. University Institute of Advanced Studies entitled "The International Regime for Bioprospecting: Existing Policies and Emerging Issues for Antarctica."

The ability of an exopolymer of glycoproteic character (GP) excreted by a new gram-negative specie Pseudoalteromonas antarctica NF3, to coat phosphatidylcholine (PC) liposomes and to protect these bilayers against the action of the nonionic surfactant octyl glucoside (OG) has been investigated. TEM micrographs of freeze-fractured liposome/GP aggregates reveal that the addition of GP to liposomes led to the formation of a covering structure (polymer adsorbed onto the bilayers) that tightly coated PC bilayers. The complete coating was already achieved when the proportion of GP assembled with liposomes was approximately 10% (wt% vs total PC). Higher GP amounts resulted in a growth of this coating structure which exhibited at the highest GP proportion in the system (31% of assembled GP) a multilayered structure. An increasing resistance of PC liposomes to be affected by OG both at sublytic and lytic levels occurred as the proportion of GP in the system rose; this protective effect being more effective when the proportion of assembled GP was 10-20% in weight. Thus, although a direct dependence was found between the growth of the enveloping structure and the resistance of the coated liposomes to be affected by OG, the best protection occurred when the proportion of assembled GP was about 10 wt%.

The phenotypic and agarolytic features of an unidentified marine bacteria that was isolated from the southern Pacific coast was investigated. The strain was gram negative, obligately aerobic, and polarly flagellated. On the basis of several phenotypic characters and a phylogenetic analysis of the genes coding for the 16S rRNA, this strain was identified as Pseudoalteromonas antarctica strain N-1. In solid agar, this isolate produced a diffusible agarase that caused agar softening around the colonies. An extracellular agarase was purified by ammonium sulfate precipitation, gel filtration, and ion-exchange chromatography on DEAE-cellulose. The purified protein was determined to be homogeneous on the basis of sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and it had a molecular mass of 33 kDa. The enzyme hydrolyzed the β-1,4-glycosydic linkages of agar, yielding neoagarotetraose and neoagarohexaose as the main products, and exhibited maximal activity at pH 7. The enzyme was stable at temperatures up to 30°C, and its activity was not affected by salt concentrations up to 0.5 M NaCl.

Species of the genus Pseudoalteromonas are frequently isolated from marine ecosystems and appear to be particularly abundant in Antarctic coastal waters. Most Pseudoalteromon as strains isolated from sea ice and underlying seawater samples are phenotypically similar to the species Pseudoalteromonas antarctica and Pseudoalteromonas nigrifaciens. However, a minority of isolates were recognized by phenotypic, DNA-DNA hybridization and 16S rRNA-based phylogenetic studies to represent a distinct genospecies clustering at the periphery of the non-pigmented Pseudoalteromon as species clade. These strains are non-pigmented, halotolerant psychrotrophs that are capable of hydrolysing starch and chitin, and possess a DNA G+C content of 38–39 mol%. It is proposed that this group represents a novel species, Pseudoalteromon as prydzensis sp. nov., for which the type strain is ACAM 620T.