The South African Gracilaria industry has experienced a number of setbacks over the last decade in the form of complete or partial die-offs of the agarophyte growing in Saldanha Bay, which may be attributed to bacterial infection.
Send correspondence to J. This article has been cited by other articles in PMC. The purified agarase Aga21 revealed a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, with an apparent molecular weight of 80 kDa.
The optimum pH and temperature of the agarase were 8. The enzymatic hydrolyzed product of agar was characterized as neoagarobiose.
Furthermore, this work is the first evidence of cold-adapted agarase in Antarctic psychrophilic bacteria and these results indicate the potential for the Antarctic agarase as a catalyst in medicine, food and cosmetic industries. Agarase, a glycoside hydrolase GHcan hydrolyze agarose.
To date, most of the agarases have been isolated from various sources, including seawater, marine sediments, marine algae, marine mollusks, fresh water, and soil Fu and Kim, ; however, agarases isolated from the Antarctic environment have not yet been reported.
The Antarctic marine environment is perennially cold, and in some cases, it is permanently covered with ice. Spatial heterogeneity, combined with extreme seasonal fluctuations such as those experienced during the annual sea-ice formation events, results in a high diversity of microbial habitats and, therefore, microbial communities Karl, Extreme environments are proving to be a valuable source of microorganisms that secrete interesting novel molecules, including enzymes, lipids, exopolysaccharides, and other active substances.
The enzymes produced by psychrophilic and psychrotrophic microorganisms with unique physiological and biochemical characteristics have significant advantages in some areas in comparison to the enzymes from mesophiles Chintalapati et al.
Until recently, agarases produced by Antarctic microorganisms were an unknown entity. After the enzyme was purified, its characteristics in terms of enzyme activity were analyzed under different temperature and pH conditions.
This study is the first to report on a cold-adapted agarase derived from the Antarctic psychrophilic strain.
The strain was inoculated on a E medium containing 0. After being cultured for 24 h on E, the strain was inoculated on selection plates containing agar as the sole source of energy and carbon; positive colonies showing clear zones or pits were selected. Purification of agarase To isolate agarase, the agarase-producing strain was grown in mL vials containing mL of the E liquid medium supplemented with 0.
The precipitate was dissolved in sodium phosphate buffer pH 6. The dialyzed sample was concentrated with a polyethylene glycol 20, solution. The crude enzyme solution was filtered through a 0.
The concentrated crude enzyme solution was then applied onto a Q-Sepharose F.
The column was washed with 50 mL of the same buffer to remove the unbound proteins. The enzyme was eluted in 1. The fractions with the highest enzyme activities were pooled and further purified via gel filtration on a Sephacryl S column using the same buffer.
Agarase enzyme assay The specific activity of the purified Aga21 was determined according to a modified method developed by Ohta et al. Appropriately diluted enzyme solution was added to different substrates in Tris-HCl pH 8. The activity was expressed as the initial rate of agar hydrolysis by measuring the release of reducing ends using the 3,5-dinitrosalicylic acid DNS procedure with D-galactose as the standard Miller, Effect of pH, temperature, and additives In each experiment, 1.
The relative agarase activity was determined using the DNS method. The optimum pH was tested at a pH range of 3. The assay mixture without the addition of metal ion salts or chelator was used as the control.
Identification of Agahydrolyzed agar products Thin layer chromatography TLC was used to identify the hydrolysis products of agar. The TLC plates were developed using a solvent system consisting of n-butanol, acetic acid, and water 2: Carbon nuclear magnetic resonance spectroscopy After enzymatic hydrolysis, the oligomers were precipitated with iso-propanol and dried at room temperature.
Results Isolation and identification of strain NJ21 Initially, the agarase-producing Antarctic psychrophilic strain was isolated from the selection plates showing a clear hydrolysis pit Figure 1.
And, hence, was assigned to the genus Pseudoalteromonas and named Pseudoalteromonas sp.
NJ21 GenBank accession number:Gracilaria species are an important source of agar. The South African Gracilaria industry has experienced a number of setbacks over the last decade in the form of complete or partial die-offs of the agarophyte growing in Saldanha Bay, which may be attributed to bacterial infection.
An extracellular β-agarase was purified from Pseudoalteromonas sp. NJ21, a Psychrophilic agar-degrading bacterium isolated from Antarctic Prydz Bay sediments.
The purified agarase (Aga21) revealed a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, with an apparent molecular weight of 80 kDa. The Role of Agarase in Agar-Degrading Bacteria Abstract Agar-Degrading (agarolytic) Bacteria is physiological class of bacteria capable of utilising agar as a sole carbon source.
This ability is made available by the use of agarases - enzymes which break down agarose into oligosaccharides. Flammeovirga pacifica strain WPAGA1 is a Gram-negative, polysaccharide-degrading bacterium isolated from the marine sediment of the West Pacific Ocean.
This strain is a cosmopolitan marine bacterium that uses complex polysaccharides as exclusive source of carbon and energy and plays a key role in.
The Role of Agarase in Agar-Degrading Bacteria Abstract Agar-Degrading (agarolytic) Bacteria is physiological class of bacteria capable of utilising agar as a sole carbon source. Agarase (EC , AgaA, AgaB, endo-beta-agarase, agarose 3-glycanohydrolase) is an enzyme with systematic name agarose 4-glycanohydrolase.
It is found in agarolytic bacteria and is the first enzyme in the agar catabolic pathway.