• Microbiology and Biotechnology Letters
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• v.49 no.3
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• pp.374-383
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• 2021

Rhizoctonia solani is one of the major pathogens that cause sheath blight disease in rice. Sheath blight is one of the most difficult diseases to control. Biological control (with the use of rhizobacteria) is one of the ways to control this disease. Plant Growth Promoting Rhizobacteria (PGPR) is a rhizosphere bacterium that can be used to enhance plant growth. The composition of the rhizobacteria in organic and nonorganic soil is affected by the chemical characteristics of the soil - which influences plant physiology and root exudation patterns. This study aimed to obtain a species of rhizobacteria which shows PGPR activity, from organic and nonorganic rice fields and test their capability to suppress R. solani growth. Out of 23 isolates screened for PGPR activity, the following isolates showed high PGPR activity and were selected for in vitro antagonistic activity testing against R. solani: ISO6, ISO11, ISO15, ISN2, ISN3, and ISN7, The six isolates produced 43,42-75,23 ppm of IAA, possessed phosphorus solubilization capability, and chitinase-producing activity. ISO6 (54.88%) and ISN7 (83.33%) displayed high inhibition capacities against R. solani, in vitro. ISO6 and ISN7 inhibited the growth of R. solani lesions on rice leaves by 89% and 100% (without lesion), respectively, after 7 days of incubation. Analysis of their 16S rRNA sequences revealed that the ISO6 isolate was Citrobacter freundii and ISN7 isolate was Pseudomonas aeruginosa.

• Journal of Mushroom
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• v.18 no.3
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• pp.208-213
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• 2020

Burkholderia contaminans PSB-A and Burkholderia ambifaria PSB-B were isolated from button mushroom bed to estimate their phosphate solubility. The phosphate-solubilizing abilities of these strains were assessed by measuring the phosphorus content in a single and co-inoculation medium for 7 days. The co-inoculation of these two strains released the highest content of soluble phosphorus (166.3 ㎍ mL^-1) into the medium, followed by single inoculation of B. contaminans PSB-A (143.73 ㎍ mL^-1) and B. ambifaria PSB-B (127.1 ㎍ mL^-1). The highest pH reduction, organic acid production, and glucose consumption were also observed in the co-inoculation medium. According to the plant growth promotion bioassay, co-inoculation enhanced the growth of romaine lettuce much more than the single inoculation (20.4% for leaf widths and 16.6% for root lengths). Although no significant difference was noted between single and co-inoculation of bacterial strains in terms of phosphorous release and plant growth, co-inoculation of PSB may have a beneficial effect on crop growth due to a synergistic effect between the strains.

• Journal of Mushroom
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• v.17 no.2
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• pp.64-69
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• 2019

The present study was conducted to investigate the synergistic effects caused by single and co-inoculation of the phosphate solubilizing bacteria (PSB), Paraburkholderia phenazinium YH3 and Paraburkholderia metrosideri YH4. Phosphate solubilization was assessed by measuring the phosphorus contents for 7 days in a single and co-inoculation medium. Co-inoculation of the two strains was found to release the highest content of soluble phosphorus ($1,250{\mu}g\;mL^{-1}$) into the medium, followed by the single inoculation of P. metrosideri YH4 ($1196.59{\mu}g\;mL^{-1}$) and P. phenazinium YH3 ($994.34{\mu}g\;mL^{-1}$). The highest pH reduction, organic acid production and glucose consumption was also observed in the co-inoculation medium of the two strains. A plant growth promotion bioassay revealed that co-inoculation with the two strains enhanced the growth of romaine lettuce more than single inoculation with either of the two strains (28.5% for leaf and 16.6% for root). Although there was no significant difference between single and co-inoculation of bacterial strains in terms of phosphorous release and plant growth, the synergistic effects of co-inoculation with PSB could be beneficial for crop growth.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.51 no.3
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• pp.230-237
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• 2018

This study investigated the food and nutritional characteristics of alkaline-insoluble fractions (AIFs) recovered from bastard halibut Paralichthys olivaceus (BH) and skipjack tuna Katsuwonus pelamis (ST) roes using the alkaline solubilization. The moisture content of AIFs ranged from 4.8% to 12.8%, and ST provided significantly better yields (9.5 for STAIF-11 and 7.1 g/100 g roe for STAIF-12) than did BH (P<0.05). The protein content of AIFs ranged from 71.7% to 79.2%, with the highest level yielded by STAIF-11 (6.8 g/100 g roe). The crude fat content of AIFs was 10.9-14.3% and the mineral content was 0.7-3.4%. The major mineral components of AIFs were sulfur, sodium, potassium, and phosphorus. Color values showed that BHAIFs were significantly brighter than STAIFs. Total contents of essential amino acids were significantly higher in STAIFs (47.5-49.5%) than in BHAIFs. The major essential amino acids found in AIFs from both sources were Val, Leu, Lys, and Arg. Therefore, AIFs were significantly superior to whole BH roe in terms of physicochemical and nutritional status, and we identified species-specific differences between BH and ST. Protein is a major component of AIFs recovered from fish roes, which suggests that they have potential for use as a protein source.

• Korean Journal of Environmental Agriculture
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• v.28 no.2
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• pp.165-170
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• 2009

The increase in P availability to rice under flooded soil conditions involves the reductive dissolution of iron phosphate and iron (hydr)oxide phosphate. However, since $NO_3^-$ is a more favourable electron acceptor in anaerobic soils than Fe, high$NO_3^-$ loads function as a redox buffer limiting the reduction of Fe. The effect of adding $NO_3^-$ on Fe reduction and P release in paddy soil was investigated. Pot experiment was conducted where $NO_3^-$ was added to flooded soil and changes of redox potential and $Fe_2^+$, $NO_3^-$ and $PO_4^{3-}$ concentrations in soil solution at 10 cm depth were monitored as a function of time. Redox potential decreased with time to -96 mV, but it was temporarily poised at about 330${\sim}$360 mV when $NO_3^-$ was present. Nitrate addition to soil led to reduced release of $Fe_2^+$ and prevented the solubilization of P. Phosphate in pore water began to rise soon after incubation and reached final concentrations about 0.82 mg P/L in the soil without $NO_3^-$ addition. But, in the soil with $NO_3^-$ addition, $PO_4^{3-}$ in pore water was maintained in the range of 0.2${\sim}$0.3 mg P/L. The duration of inhibition in $Fe_2^+$ release was closely related to the presence of $NO_3^-$, and the timing of $PO_4^{3-}$ release was inversely related to the $NO_3^-$ concentration in soil solution. The results suggest that preferential use of $NO_3^-$ as an electron acceptor in anaerobic soil condition can strongly limit Fe reduction and P solubilization.

• BMB Reports
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• v.30 no.2
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• pp.106-112
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• 1997

The effect of cryopreservation on extracellular matrix was studied with the ultimate objective of permiting a prediction of the tendency of aorta conduit tissue to calcify following transplantation. Cryopreserved and fresh porcine aorta conduit tissues were extracted using guanidine-hydrochloride (Gdn-HCl) followed by sequential digestion of the tissues with collagenase, elastase, and papain. Glycosaminoglycans (GAGs) of the proteoglycans (PGs) were isolated and quantitated. Gdn-HCl extracted about 61% and 62% of the total GAG (proteoqlycan) material from cryopreserved and fresh tissues, respectively. Collagenasesolubilized proteoglycans from Gdn-HCl extracted tissue represented 20% and 13%, respectively, of the total GAGs present in cryopreserved and fresh tissues. Subsequent elastase hydrolysis of collagenase-digested tissue released about 11% of total GAGs from cryopreserved tissue and 16% from fresh tissue. The remaining 8%, from cryopreserved tissue, and 9%, from fresh tissue, of the total GAGs were obtained after using a papain hydrolysis. There was essentially no difference between fresh and cryopreserved tissues in the relative distribution of proteoglycans in the extracts and digestions except in the initial digestion step where more proteoglycans were obtained from collagenase solubilization of cryopreserved tissue than fresh tissue (p<0.05). The histologic status of the fresh and cryopreserved porcine aortic conduit did not differ markedly. The normal tissue architecture was not affected markedly by the cryopreservation procedure as neither alteration of elastic structure, fibrous proteins nor alteration of nuclear distribution or smooth muscle cell morphology was detected. Quantitative tissue mineral studies revealed that the mean calcium content of the cryopreserved aorta conduit tissue $(165{\pm}3\;{\mu}g/g\;wet\;tissue)$ was higher than that of the fresh tissue $(105{\pm}4\;{\mu}g/g\;wet\;tissue)$ $(p<0.05)$. The mean phosphorus content was $703{\pm}35\;{\mu}g$ wet tissue from cryopreserved tissue and $720{\pm}26\;{\mu}g$ wet tissue from fresh tissue. The study indicates that there is no significant alteration in the distribution of PGs in properly cryopreserved tissue, but the total calcium level appears to be increased in tissue cryopreserved by the cryopreservation process used in this study.

• Journal of Microbiology and Biotechnology
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• v.20 no.11
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• pp.1577-1584
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• 2010

In total, 140 halotolerant bacterial strains were isolated from both the soil of barren fields and the rhizosphere of six naturally growing halophytic plants in the vicinity of the Yellow Sea, near the city of Incheon in the Republic of Korea. All of these strains were characterized for multiple plant growth promoting traits, such as the production of indole acetic acid (IAA), nitrogen fixation, phosphorus (P) and zinc (Zn) solubilization, thiosulfate ($S_2O_3$) oxidation, the production of ammonia ($NH_3$), and the production of extracellular hydrolytic enzymes such as protease, chitinase, pectinase, cellulase, and lipase under in vitro conditions. From the original 140 strains tested, on the basis of the latter tests for plant growth promotional activity, 36 were selected for further examination. These 36 halotolerant bacterial strains were then tested for 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity. Twenty-five of these were found to be positive, and to be exhibiting significantly varying levels of activity. 16S rRNA gene sequencing analyses of the 36 halotolerant strains showed that they belong to 10 different bacterial genera: Bacillus, Brevibacterium, Planococcus, Zhihengliuella, Halomonas, Exiguobacterium, Oceanimonas, Corynebacterium, Arthrobacter, and Micrococcus. Inoculation of the 14 halotolerant bacterial strains to ameliorate salt stress (150 mM NaCl) in canola plants produced an increase in root length of between 5.2% and 47.8%, and dry weight of between 16.2% and 43%, in comparison with the uninoculated positive controls. In particular, three of the bacteria, Brevibacterium epidermidis RS15, Micrococcus yunnanensis RS222, and Bacillus aryabhattai RS341, all showed more than 40% increase in root elongation and dry weight when compared with uninoculated salt-stressed canola seedlings. These results indicate that certain halotolerant bacteria, isolated from coastal soils, have a real potential to enhance plant growth under saline stress, through the reduction of ethylene production via ACC deaminase activity.

• Korean Journal of Soil Science and Fertilizer
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• v.47 no.3
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• pp.141-146
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• 2014

The necessity to develop economical and eco-friendly technologies is steadily increasing. Plant growth promoting rhizomicrobial strains PGPR are a group of microorganisms that actively colonize plant roots and increase plant growth and yield. Pot experiments were used to investigate the potential of some rhizobacterial strains to enhance the Brassica rapa growth. Microbial strains were successfully isolated from the rhizosphere of Panax ginseng and characterized based on its morphological and plant growth promotion characters. Surface disinfected seeds of Wisconsin Fast B. rapa were inoculated with the selected PGPR microorganisms. The different pots treatments were inoculated by its corresponding PGPR ($10^7cfu\;mL^{-1}$) and incubated in the growth chamber at $25^{\circ}C$ and 65% RH, the light period was adjusted to 24 hours (day). NPK chemical fertilizer and trade product (EMRO, USA) of effective microorganisms as well as un-inoculated control were used for comparison. Plants harvested in 40 days were found to have significant increase in leaf chlorophyll units and plant height and also in dry weight of root and shoot in the inoculated seedlings. Root and shoot length and also leaf surface area significantly were increased by bacterial inoculation in sterile soil. The study suggests that Rhodobacter capsulatus and Azotobacter chroococcum are beneficial for B. rapa growth as they enhance growth and induced IAA production and phosphorus solubilization. This study presents some rhizomicrobial strains that significantly promoted growth of Wisconsin Fast Plant B. rapa in pot experiment under different soil conditions.

• Journal of Microbiology and Biotechnology
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• v.31 no.9
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• pp.1218-1230
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• 2021

Cold-adapted plant growth-promoting bacteria (PGPB) with multiple functions are an important resource for microbial fertilizers with low-temperature application. In this study, culturable cold-adapted PGPB strains with nitrogen fixation and phosphorus solubilization abilities were isolated. They were screened from root and rhizosphere of four dominant grass species in nondegraded alpine grasslands of the Qilian Mountains, China. Their other growth-promoting characteristics, including secretion of indole-3-acetic acid (IAA), production of siderophores and ACC deaminase, and antifungal activity, were further studied by qualitative and quantitative methods. In addition, whether the PGPB strains could still exert plant growth-promoting activity at 4℃ was verified. The results showed that 67 isolates could maintain one or more growth-promoting traits at 4℃, and these isolates were defined as cold-adapted PGPB. They were divided into 8 genera by 16S rRNA gene sequencing and phylogenetic analysis, of which Pseudomonas (64.2%) and Serratia (13.4%) were the common dominant genera, and a few specific genera varied among the plant species. A test-tube culture showed that inoculation of Elymus nutans seedlings with cold-adapted PGPB possessing different functional characteristics had a significant growth-promoting effect under controlled low-temperature conditions, including the development of the roots and aboveground parts. Pearson correlation analysis revealed that different growth-promoting characteristics made different contributions to the development of the roots and aboveground parts. These cold-adapted PGPB can be used as excellent strain resources suitable for the near-natural restoration of degraded alpine grasslands or agriculture stock production in cold areas.

• The Korean Journal of Mycology
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• v.41 no.4
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• pp.218-224
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• 2013

Of 1,100 yeast strains which were isolated from various Korean fermented foods, screened for phosphate solubilization, five strains showed the ability to solubilize tricalcium phosphate. The 26S rDNA domain D1-D2 sequence analysis revealed the identification of strain Y393 and Y524 as Pichia anomala (99.8 and 100% identity, respectively), Y669 as Pichia farinosa (100% identity), Y901 as Candida versatilis (100% identity), and Y1101 as Pichia subpelliculosa (100% identity). All the phosphate solubilizing strains showed mesophilic characteristics. The temperature range for growth of 4 strains was $20{\sim}35^{\circ}C$ and P. farinosa Y669 was able to grow up to $45^{\circ}C$. The strain C. versatilis Y907 was able to grow at pH range of 5.0~6.0 and showed halophilic characteristics with tolerance to 15% of NaCl concentration. The Phosphate solubilizing yeast strains were survived well in bed soil for 8 weeks which were maintained densities of $10^7{\sim}10^8$ cfu/g. The highest phosphate solubilizing activity was observed in P. subpelliculosa Y1101. It solubilized 697.2 ug/mL of phosphorus from tricalcium phosphate with decrease in pH from 6.8 to 4.37 after 11 days of inoculation.