In this study, to select strains suitable as microbial agent from among rhizosphere microorganisms present in rhizosphere soil and roots, the mineral solubilization ability, antifungal activity against 10 types of plant pathogenic fungi, and plant growthpromoting activity of rhizosphere microorganisms were evaluated. As a result, DDP346 was selected because it has solubilization ability of phosphoric acid, calcium carbonate, silicon, and zinc; nitrogen fixing ability; production ability of siderophore, indole-3-acetic acid, and aminocyclopropane-1-carboxylate deaminase; and antifungal activity against seven types of plant pathogenic fungi. DDP346 showed a 99.9% homology with Acinetobacter pittiiDSM 21653 (NR_117621.1); phylogenetic analysis also revealed a close relationship with Acinetobacter pittii based on the 16S rRNA base sequence. The growth conditions of DDP346 wereidentified as temperatures in the range of 10-40℃, pH in the range of 5-11, and salt concentrations in the range of 0-5%. In addition, a negative correlation coefficient (r2 = −0.913, p <0.01) was shown between pH change and the solubilized phosphoric acid content of Acinetobacter sp. DDP346, and this is assumed to be due to the organic acid generated during culture. Consequently, through the evaluation of its mineral solubilization ability, antifungal activity against plant pathogenic fungi, and plant growthpromoting activity, the potential for the utilization of Acinetobacter sp. DDP346 as a multi-purpose microbial agent is presented.
J Appl Biol Chem (2021), 64: 333-341.
The purpose of this study was to evaluate the antifungal activity, plant-growth-promoting activity, andmineral solubilization ability of 10 species of phytopathogenic fungi to select a Bacillus sp. fromrhizosphere soils and roots that can be used as a microbial agent. The antifungal activity for phytopathogenic fungi varied based on the Bacillus sp. Among the selected strains, DDP4, DDP16, DDP148, SN56, and SN95 exhibited antifungal activity for nine or more species of phytopathogenic fungi. Regarding nitrogen-fixation ability, all Bacillus sp. showed similar levels of activity, and siderophore production ability was relatively high in ANG42 and DDP427. The indole-3-acetic acid production abilities were in the range of 1.83-67.91 μg/ml, with variations in activity based on the Bacillus sp. One strain with a high activity was selected from each species, and their mineral solubilization abilities were examined. Most Bacillus sp. could solubilize phosphoric acid and calcium carbonate, and DDP148 and SN56 could solubilize silicon and zinc, respectively. These results suggested that Bacillus sp. can be considered potential multi-purpose microbial agents for plant growth promotion and disease prevention.
Microbiol. Biotechnol. Lett. (2021), 49: 576-586.
This study aimed to identify plant growth-promoting activity, phytopathogenic fungi growth inhibitoryactivity, mineral solubilization ability, and extracellular enzyme activity of the genus Bacillus in soiland the rhizosphere. With regards to antifungal activity against phytopathogenic fungi, DDP257 showed antifungal activity against all 10 pathogenic fungi tested. ANG20 showed the highest ability to produce indole-3-acetic acid, a plant growth-promoting factor (70.97 μg/ml). In addition, 10 species were identified to have 1-aminocyclopropane-1-carboxylate deaminase production ability, and most isolates showed nitrogen fixation and siderophore production abilities. Thereafter, the isolated strains’ ability to solubilize minerals such as phosphate, calcite, and zinc was identified. With extracellular enzyme activity, the activity appeared in most enzymes. In particular, all the strains showed similar abilities for alkaline phosphatase, esterase (C4), acid phosphatase, and naphtol-AS-BI-phosphohydrolase production. This result was observed because the genus Bacillus secreted various organic substances, antibiotics, and extracellular enzymes. Therefore, through the results of this study, we suggest the possibility of using strains contributing to the improvement of the soil environment as microbial agents.
Microbiol. Biotechnol. Lett. (2021), 49: 403-412.
The purpose of this study was to confirm the antifungal activity, plant growth-promoting activity, andmineral solubilizing activity of 18 types of bacteria isolated purely from rhizosphere soil. The potentialof isolates of the genus Bacillus and Pseudomonas as biocontrol agents was confirmed through the antifungal activity of these isolates. This activity has been determined to be due to various hydrolytic enzymes on the cell wall of plant pathogenic fungi and the production of siderophores in isolates. Inaddition, most of the isolates have been found to have aminocyclopropane-1-carboxylate deaminaseproduction activity, indole-3-acetic acid production activity, and nitrogen fixation activity. These characteristics are believed to have a positive effect on root development, growth, and the productivityof crops via a reduction in the concentration of ethylene under conditions of environmental stress, to which plants are commonly exposed. In addition, on testing for the solubilizing activity of the isolatesfor phosphoric acid, silicon, calcium carbonate, and zinc, some isolates were found to have mineralsolubilizing activities. Inoculation of these isolates during plant growth is expected to assist plantgrowth by converting nutrients necessary for growth into usable forms that can be absorbed by plants.The 18 isolated strains can be used as biocontrol agents due to their antifungal activity, plant growthpromoting activity, and mineral solubilizing activity.
Journal of Life Science (2021), 31: 641-653.
This study aimed to compare the quality characteristics of pomegranate juice based on the extraction methods applied: centrifugal, single-gear, and twin-gear. Changes in the metabolic activities during digestion condition were further investigated. The twin-gear method was eventually identified as the optimal method, through comprehensive evaluation of the extraction rate, particle size, proximate composition, and the mineral and vitamin contents. Pomegranate juice derived using the twin-gear method had high-levels of bioactive substances such as phenolic compounds, flavonoids, anthocyanins, and selenium. Consequently, this juice exerted significant inhibitory effects on lipid peroxidation. Phenolic compounds are known to exhibit a high-correlation with skin-lightening, anti-aging, and anti-diabetic activities. An in vitro digestion model was used to evaluate changes in the antioxidant and angiotensin converting enzyme (ACE) inhibitory activities. Compared to levels observed before digestion, the results revealed a marked increase in the 2,2′- azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging, ferric reducing antioxidant power, and superoxide dismutase-like activities as digestion progressed through the gastric phase condition, whereas most of these effects were stabilized or inhibited as digestion progressed through the intestinal phase. The ACE inhibitory activity was observed to increase after being subjected to gastric and intestinal digestion conditions. The correlation coefficients (r2) for ACE inhibition and antioxidant activities were in the range 0.681∼0.952, thus indicating a highly positive correlation. The findings of this study indicate that the bioactivity of pomegranate juice is enhanced, as determined by the increase in various physiological activities as well as increase in the bioaccessibility and bioavailability of bioactive substances during digestion.
한국식품영양과학회지 50: 136-148(2021)
This study proposes the processing method that could maximize the functional properties of evening primrose seeds (EPS) and its various nutritional components. EPS can be prepared by different methods, such as being left raw, roasting, steaming, and powdering. Processing of EPS to create EPS powder (EPSP) resulted in higher levels of vitamin E, fatty acids, total phenolic contents, and antioxidant activity, compared with the other processing methods. Also, EPSP maintained lipid peroxidation inhibitory activity for 49 days. In particular, the EPSP ethyl acetate (EtOAc) fraction exhibited high antioxidant, antidiabetic, and angiotensin I-converting enzyme inhibitory activities. The EPSP ethyl acetate fraction showed a high cytoprotective effect against H2O2-induced cell damage in both RAW264.7 and EA.hy926 cells. In addition, the EtOAc fraction showed anti-inflammatory activity by the inhibitory activity of nitric oxide (NO) in RAW264.7 cells, and antihypertensive activity by the activity of NO in EA.hy926 cells. These results suggest that EPSP could be useful as a food ingredient that assists the prevention of various diseases caused by oxidative stress.
Preventive Nutrition and Food Science 25: 422-431(2020)
Oat seed juice was prepared with carrots, safflower seeds, evening primrose seeds, whole buckwheat, sesame, and oats, which was the main ingredient and has various functions. The potential of this juice as a novel functional meal replacement was assessed. The final amount of oats added was 60 g based on the combined results of total phenolic content (TPC), total flavonoid content (TFC), and β-glucan content. Nutrient and mineral content analysis revealed higher contents in naked oat seed juice, whereas vitamin analysis indicated higher levels in hulled oat seed juice. Both hulled and naked oat seed juices showed high 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2′- azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activities. Anti-skin aging and anti-diabetic activities were also observed, as indicated by high correlations with TPC, TFC, DPPH radical scavenging, and ABTS radical scavenging activities. To investigate changes in these activities according to the consumption of oat seed juice, an in vitro digestion model was used. The results show significant increases in TPC and TFC antioxidant contents after digestion. ABTS radical scavenging activity, ferric reducing antioxidant power, and superoxide dismutase-like activity significantly increased after digestion. Therefore, this study confirms the excellent quality characteristics and increased active ingredient contents of oat seed juice based on evaluation of an in vitro digestion process.
한국식품영양과학회지 49: 1105-1114(2020)
This study was conducted to investigate both plant growth-promoting and plant disease- controlling activities of bacterial strains isolated from soil. All the isolated strains were able to grow at various temperatures. All the strains, except ANG40, showed antagonistic effects against various phytopathogenic fungi. This antagonism can be ascribed to the production of siderophores and antibiotic substances. In addition, all the strains showed abilities such as nitrogen fixation, phosphate solubilization, and siderophore production. These results suggest that nitrogen, phosphorus, and iron can be converted into forms that can be easily absorbed by the plants for their growth. Analysis of the growth-promoting properties revealed that ANG51 produced 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase and indole-3-acetic acid (IAA) both of which are related to ethylene production. In contrast, the other strains were found to have only IAA-producing ability. Therefore, this study suggests that Pseudomonas geniculata ANG3, Exiguobacterium acetylicum ANG40, and Burkholderia stabilis ANG51, which were selected through analysis of comparative advantages for both plant growth promotion and disease-controlling activity, may be used as biological agents.
Microbiol. Biotechnol. Lett. (2020), 48(1), 38–47
This study was carried out to examine the antagonistic effect against phytopathogenic fungi of isolated strains from soil samples collected from Busan, Changwon, and Jeju Island: Botrytis cinerea, Colletotrichum acutatum, Corynespora cassiicola, Fusarium sp., Rhizoctonia solani, Phytophthora capsici, and Sclerotinia sclerotiorum. According to results of our studies, isolated strains showed an antagonistic effect against phytopathogenic fungi. Such an antagonistic effect against phytopathogenic fungi is seen due to the production of siderophores, antibiotic substances, and extracellular amylase, cellulase, protease, and xylanase enzyme activities. Extracellular enzymes produced by isolated strains were significant, given that they inhibited the growth of phytopathogenic fungi by causing bacteriolysis of the cell wall of plant pathogenic fungi. This is essential to break down the cell wall of plant pathogenic fungi and thus help plant growth by converting macromolecules, which cannot be used by the plant for growth, into small molecules. In addition, they are putative candidates as biological agents to promote plant growth and inhibit growth of phytopathogenic fungi through nitrogen fixation, indole-3-acetic acid production, siderophore production, and extracellular enzyme activity. Therefore, this study suggests the possibility of using Bacillus subtilis ANGa5, Bacillus aerius ANGa25, and Bacillus methylotrophicus ANGa27 as new biological agents, and it is considered that further studies are necessary to prove their effect as novel biological agents by standardization of formulation and optimization of selected effective microorganisms, determination of their preservation period, and crop cultivation tests.
Microbiol. Biotechnol. Lett. (2019), 47(4), 603–613
The steep increase in the global aged population necessitates the development of a novel diet considering the physical and physiological characteristics of the elderly. The unique problems of aged people include decreased digestion and absorption, dental loss with increasing age, and reduced general muscle reﬂexes involved in swallowing. The intake of whole vegetables and whole grains is often difﬁcult for older people to digest and absorb them, causing discomfort even after meals. Thus, the demand for the development of a Home Meal Replacement (HMR) that can be enhanced absorption of nutrition and enjoyed easily by both the elderly and busy modern people, is high. The modern society has also features the global problem of higher incidence of various liver diseases caused by increased exposure to toxic substances due to smoking, alcohol consumption, and environmental pollution (Marcellin and Kutala, 2018). Liver plays a crucial role in the metabolism of major nutrients, energy homeostasis, metabolism of hormones, detoxiﬁcation, and immune or antimicrobial actions. Various drugs based on natural substances have been developed for hepatic diseases. Generally, CCl4- or D-galactosamine-induced liver damage is used as a model for studies on developing hepato-protective or therapeutic drugs. CCl4 treatment leads to the production and activation of reactive intermediates including trichloromethyl radical (CCl3) and its derivative, trichloromethylperoxy radical (CCl3OO), via its metabolism mediated by cytochrome P450 (CYP2E1) in liver microsome (Dai et al., 2014). The generated free radicals cause lipid hyperoxidation by attacking the lipid membranes in the vicinity, induce hepatotoxicity involving necrosis, and promote fatty inﬁltration or reduced microsomal enzyme activity by binding to the macromolecules such as intracellular proteins and lipids. They can change the antioxidant status of the tissues including the release of cytosolic enzymes, such as alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), and lactate dehydrogenase (LDH), into the serum, and ultimately mediate apoptosis (Shen et al., 2015). Hence, the removal of ROS is critical in the treatment and prevention of hepatic diseases. Thus, regarding liver damage as the major cause of chronic diseases in modern society, this study aimed to develop a functional meal replacement that can fulﬁll multiple requirements, such as: (a) convenient to use by the elderly and busy modern people, (b) useful in maintaining liver health, and (c) able to prevent and treat hepatic diseases. For this, a Meal Replacement Seeds Juice (MRSJ) was prepared by mixing four types of seeds, which exhibit a diverse nutrients and functionality, with sweet potatoes (Ipomoea batatas L.), a popular ingredient in meal replacement, and carrots, a widely used ingredient in vegetable juices. The potential of MRSJ in the development of a functional meal replacement was evaluated with an aim to propose a novel form of food intake in the busy and aged modern society.
Food Science and Biotechnology(2019)