To develop eco-friendly microbial inoculants, siderophore-producing bacteria were isolated and identified, and their production characteristics and plant growth-promoting abilities were investigated. A strain S21 was isolated from rhizosphere of Korean perilla (Perilla frutescens) and identified as Enterobacter amnigenus by phenotypic properties and 16S rRNA gene sequencing. The highest siderophore production was obtained in a medium containing 0.5% fructose, 0.1% urea, 0.5% K2HPO4 and 0.1% succinic acid. By using this improved medium, siderophore production increased by 2.5 times compared to that of basal medium. The strain S21 showed insoluble phosphate solubilizing, ammonification and antifungal activities, and also produced hydrolytic enzymes (protease and lipase), indoleacetic acid and 1-aminocyclopropane-1-carboxylate deaminase. Our data suggest that E. amnigenus S21 is a potential candidate that can be used as eco-friendly biocontrol agent and biofertilizer.

To develope a microbial weed control agent, HCN-producing bacteria were isolated, and their characteristics were investigated. A selected strain of WA15 was identified as Pseudomonas koreensis by morphological, cultural, biochemical and 16S rRNA gene analyses. The conditions for HCN production was investigated by a One-Variable-at-a-Time (OVT) method. The optimal HCN production conditions were tryptone 1%, glycine 0.06%, NaCl 1% , and an initial pH and temperature of 5.0 and 30℃, respectively. The major component for HCN production was glycine. Under optimal conditions, HCN production was about 3 times higher than that of the basal medium. The WA15 strain had physiological activities, such as indoleacetic acid that was associated with the elongation of plant roots and siderophore and ammonification inhibiting fungal growth, and produced hydrolytic enzymes, such as cellulase, pectinase and lipase. The strain was able to inhibit the growth of phytopathogenic fungi, such as Rhizoctonia solani, Botrytis cinerea and Fusarium oxysporum, by the synergistic action of volatile HCN and diffusible antimicrobial compounds. A microscopic observation of R. solani that was teated with the WA15 strain showed morphological abnormalities of fungal mycelia, which could explain the role of the antimicrobial metabolites that were produced by the WA15 strain. The volatile HCN produced by the WA15 strain was also found to have insecticidal activity against termites. Our results indicate that Pseudomonas koreensis WA15 can be applied as a microbial agent for weed control and also as a termite repellent. Furthermore, it could be applied as a microbial termiticidal agent to replace synthetic insecticides.

The objective of this study was to investigate the adsorption potential of chicken feathers for the removal of OrangeⅡ (AO7) from aqueous solutions. Batch experiments were performed as a function of different experimental parameters such as initial pH, reaction time, feather dose, initial OrangeⅡ concentration and temperature. The highest OrangeⅡ uptake was observed at pH 1.0. Most of the OrangeⅡ was adsorbed at 2 h and an adsorption equilibrium was reached at 6 h. As the amount of chicken feather was increased, the removal efficiency of Orange II increased up to 99%, but its uptake decreased. By increasing the initial concentration and temperature, OrangeⅡ uptake was increased. The experimental adsorption isotherm exhibited a better fit with the Langmuir isotherm than with the Freundlich isotherm, and maximum adsorption capacity from the Langmuir constant was determined to be 0.179244 mmol/g at 30℃. The adsorption energy obtained from the Dubinin-Radushkevich model was 7.9 kJ/mol at 20℃ and 30℃ which indicates the predominance of physical adsorption. Thermodynamic parameters such as ΔGo, ΔHo, and ΔSo were -12.28 kJ/mol, 20.64 kJ/mol and 112.32 J/mol K at 30℃, respectively. This indicates that the process of OrangeⅡ adsorption by chicken feathers was spontaneous and endothermic. Our results suggest that as a low-cost biomaterials, chicken feather is an attractive candidate for OrangeⅡ removal from aqueous solutions.

Lactic acid bacteria (LAB) are industrially important microorganisms for probiotics. The recent widespread application of LAB for preparation of functional food is attributable to the accumulating scientific evidence showing their beneficial effects on human health. In this study, we isolated and characterized plant-derived LAB that show angiotensin-converting enzyme (ACE) inhibitory and antioxidant activities. The selected strain K2 was isolated from Kimchi, and identified as Lactobacillus plantarum by 16S rRNA gene analysis. The strain grew under static and shaking culture systems. They were also able to grow in different culture conditions like 25℃∼37℃ temperature, 4∼10 pH range and ∼6% NaCl concentration. L. plantarum K2 was highly resistant to acid stress; survival rate of the strain at pH 2.5 and 3 were 80% and 91.6%, respectively. The strain K2 also showed high bile resistance to 0.3% bile bovine and 0.3% bile extract with more than 74% of survival rate. The cell grown on MRS agar plate containing bile extract formed opaque precipitate zones around the colonies, indicating they have bile salt hydrolase activity. The strain showed an inhibitory activity against pathogenic bacteria such as Escherichia coli, Staphylococcus aureus and Listeria monocytogenes; antibacterial activity was probably due to the lactic acid. The K2 strain showed relatively higher autoaggregation values, antihypertensive and antioxidant activities. These results suggest that L. plantarum K2 could be not only applied as a pharmabiotic for human health but also is also starter culture applicable to fermentative products.

This study demonstrated that the physiochemical properties and anti-oxidants activities of soy sauce with Oak mushroom (MK) and Astragalus memyranaceus (AK) improved in sensory acceptability and functionality during the ripening period of 30 days. The pH content was reduced and the total acidity content was increased with time. The total sugar of AK and MK was higher than traditional soy sauce (TK), and the changes in amino nitrogen of the AK increased dramatically from 0.50 to 0.98%. During the antioxidant experiments, the total polyphenol and flavonoid contents increased at a steady rate and studies showed that the DPPH free radical scavenging activities were higher in all treatments except in the traditional soy sauce. According to the results of this study, the antioxidant activities of the AK and MK were higher than the TK, while the preference for the AK and MK was higher than the TK. In conclusion, the AK could be used as a functional soy sauce.