We investigated the functionality of poly-γ-glutamic acid (γ-PGA), which is produced by Bacillus subtilis D7, for its potential applications in medicine and cosmetics. The γ-PGA had angiotensin-converting enzyme (ACE) inhibition activity. ACE inhibition activity was dependent on the γ-PGA concentration; the highest ACE inhibition activity was observed at 1.25 mg/l of γ-PGA. IC50 (0.108 mg/ml) of the γ-PGA was lower than that of standard ACE inhibitory drug, N-[(S)-mercapto-2-methylpropionyl]-L-proline (0.247 mg/ml). The γ-PGA also had water-holding capacity and hygroscopicity. Furthermore, the γ-PGA inhibited growth of some pathogenic bacteria, including Listeria monocytogenes, Salmonella typhimurium, Staphylococcus aureus, Klebsiella pneumonia and Esherichia coli. The γ-PGA exhibited a good metal adsorption capacity; Cr (VI) adsorption capacity of γ-PGA increased with decreasing pH, and the maximal adsorption was observed at pH 2. Our results suggest that γ-PGA may be expected to be widely applied in cosmetics, biomedical and environmental industries with the feature of being less harmful to humans and the environment.

Styela clava tunic is generated in large amounts as a waste from S. clava processing plants and causes environmental problem. Although biological activities of S. clava were reported by many investigators, study on S. clava tunic was little. In this study, therefore, tyrosinase inhibition and antioxidative activities of extracts from S. clava tunic using different solvent were investigated for recycling of the fishery waste. Among extraction methods tested, autoclaved extraction (25.7%) and hot water extraction (18.2%) appeared to be effective for extraction. The highest total phenolic content was 46.6 mg/g in autoclaved extract while the highest flavonoid content was 23.0 mg/g in chloroform extract. All extracts possessed tyrosinase inhibition activity and the inhibition activity was concentration-dependent. Inhibition concentration (IC50) against tyrosinase activity was 0.36×10 4 mg/ml in ethanol extract, 0.11×10 3 mg/ml in acetone extract and 0.27 mg/ml in n-butanol extract.Among extracts tested, hot water and autoclaved extracts displayed higher antioxidative activity than organic solvent extracts. Therefore, our data suggest that extract from S. clava tunic may potential candidate for cosmetic product with whitening effect and medicine for diseases caused by various oxidative stresses.

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The objectives of this study was to improve poly-γ-glutamic acid (γ-PGA) production by Bacillus subtilis D7 isolated from a Korean traditional fermented food and to assess its antioxidant activity for applications in the cosmetics and pharmaceutical industries. Strain D7 produced γ-PGA in the absence of L-glutamic acid, indicating L-glutamic acid-independent production. However, the addition of L-glutamic acid increased γ-PGA production. Several tricarboxylic acid cycle intermediates and amino acids could serve as the metabolic precursors for γ-PGA production, and the addition of pyruvic acid and D-glutamic acid to culture medium improved the yield of γ-PGA markedly. The maximum yield of γ-PGA obtained was 24.93 ± 0.64 g/l in improved medium, which was about 5.4-fold higher than the yield obtained in basal medium. γ-PGA was found to have 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity (46.8 ± 1.5 %), hydroxyl radical scavenging activity (52.0 ± 1.8 %), 2,2'-azinobis-3-ethylbenzothiazoline-6-sulfonate (ABTS) radical scavenging activity (42.1 ± 1.8 %), nitric oxide scavenging activity (35.1 ± 1.3 %), reducing power (0.304 ± 0.008), and metal chelating activity (91.3 ± 3.5 %). These results indicate that γ-PGA has a potential use in the food, cosmetics, and biomedical industries for the development of novel products with radical scavenging activity. As far as we are aware, this is the first report to describe the antioxidant activityof γ-PGA produced by bacteria.

We investigated the optimal conditions for keratinase production by feather-degrading Pseudomonas geniculata H10 using one variable at a time (OVT) method. The optimal medium composition and cultural condition for keratinase production were determined to be glucose 0.15% (w/v), beef extract 0.08% (w/v), KH2PO4 0.12% (w/v), K2HPO4 0.02% (w/v), NaCl 0.07% (w/v), MgSO4․7H2O 0.03%, MgCl2․6H2O 0.04% along with initial pH 10 at 200 rpm and 25℃, respectively. The production yield of keratinase was 31.6 U/ml in an optimal condition, showing 4.6-fold higher than that in basal medium. The strain H10 also showed plant growth promoting activities. This strain had ammonification activity and produced indoleacetic acid (IAA), siderophore and a variety of hydrolytic enzymes such as protease, lipase and chitinase. Therefore, this study showed that P. geniculata H10 could be not only used to upgrade the nutritional value of feather wastes but also useful in situ biodegradation of feather wastes. Moreover, it is also a potential candidate for the development of biofertilizing agent applicable to crop plant soil.