This research focused on the isolation and characterization of the new strains which can be used as microbial resources for auxin production in the agriculture industry. For the isolation of the new microorganism in the gut of Larimichthys polyactis, a marine agar medium was used and 3 colonies were isolated. Through the 16S-based ID service, isolated strains were identified as 1 strain of Niallia circulans and 3 strains of Proteus mirabilis. Verifying the agriculture industrial values of these isolated strains, the productivity of auxin and activity of various enzymes such as amylase, lipase, and protease were confirmed. As a result, isolated 3 strains showed auxin activity and only protease activities which means the possibility of applying them to the production of effective microorganisms in the agriculture industry.

Screening of Bacillus subtilis strains capable of producing extracellular hydrolases, including lipolytic enzyme was carried out. Within the scope of this study, total 61 strains were isolated from various domestic specific environmental samples such as seawater, soil, Jeju ranch, hot spring, salt farm, and fermented food and identified as Bacillus subtilis based on 16S rRNA sequences. Among the isolates, 4 strains had extracellular lipase activity. The growth profile of the strains revealed that 4 strains showed well growth at 50℃, 3 strains at 55℃, and pH 7.0. All strains could tolerate salinity up to 5%(w/v), 3 strains up to 10%(w/v), and only one strain showed growth at 15%(w/v). Additionally, amylolytic and proteolytic activities were detected in these strains. The highest lipolytic, amylolytic, and proteolytic activity was detected in Bacillus subtilis YS-YR 5A. These results demonstrate the potential application of extracellular hydrolase-producing Bacillus subtilis strains, especially strain YS-YR 5A, as fermentation starter to enhance the functionality and multiplication of functional natural products in the food/medicine/cosmetics/bio industries.

A novel L. harbinensis VF was isolated from fermented vinegar and identified through biochemical characteristics and 16S rRNA sequencing analysis. Characteristics of probiotics were studied for acid and bile salt tolerances, hemolytic activity, antibiotic resistance, antimicrobial activity, cell surface hydrophobicity, and aggregation. The survival rates of the isolate were maintained at 68.9% and 95.6% after 3 h incubation at pH 2.0 and 2.5 and were over 74% at bile salt concentrations of 0.3% and 0.5%. The hemolytic activity was confirmed to be -hemolysis. The isolate showed broad antibiotics-resistance in over 12 antibiotics except for trimethoprim/sulfamethoxazole, compared to L. plantarum (KCTC 3108), used as control, and previously reported L. harbinensis. Antimicrobial activity was confirmed against pathogens, B. cereus, E. coli O157:H7, L. monocytogenes, and S. typhimurium, except S. aureus, and it was attributed to produced organic acids (low pH). The hydrophobicity for xylene and chloroform were 16.7% and 20.4%, respectively, lower than those of L. plantarum (41.2% & 49.9%). The auto-aggregation and coaggregation with pathogens were 83.8% and 49.2-87.6% at 24 h incubation, respectively, higher than those of L. plantarum. From this study, L. harbinensis VF is likely to be used as a probiotic strain and is a strong candidate for commercial application.