• Journal of Microbiology and Biotechnology
• /
• v.29 no.4
• /
• pp.527-537
• /
• 2019

Three types of meongge (Halocynthia roretzi) jeotgal (MJ) were prepared with 3 different types of salts (12%, w/v): purified salt (PS), solar salt aged for 3 years (SS), and bamboo salt that had been recrystalized 3 times (BS). One set of MJ was fermented with starters, Bacillus subtilis JS2 and Tetragenococcus halophilus BS1-37 (each 6 log CFU/g), and another set without starters for 42 days at $10^{\circ}C$. The LAB count of the SSMJ (non-starter) was highest at day 28 (2.30 log CFU/g). The pH of the PSMJ and SSMJ was 5.72-5.77 at day 0, and 5.40-5.50 at day 42. BSMJ showed higher pH and lower titratable acidities than other samples. Amino-type nitrogen (ANN) increased continuously, and SSMJ showed higher values than other samples from day 14. Bacterial species of non-starter MJ were examined by culture independent method. Clone libraries of 16S rRNA genes were constructed in Escherichia coli from total DNA from non-starter MJ samples at day 0, 14, and 28. Thirty clones per each sample were randomly selected and DNA sequences were analyzed. Variovorax sp., uncultured bacterium, and Acidovorax sp. were the most dominant group at day 0, 14, and 28, respectively. Lactobacillus sakei and Streptococcus sp. were the next dominant group in SSMJ at day 28. A Streptococcus sp. was detected from PSMJ at day 28. Sensory evaluation for MJ samples at day 28 showed that SSMJ got higher overall acceptability scores. These results showed that solar salt can cause desirable changes in the microbial community of fermented foods, thereby positively affecting their overall quality.

• Asian-Australasian Journal of Animal Sciences
• /
• v.32 no.1
• /
• pp.103-109
• /
• 2019

Objective: Ensiling of tannin-rich fruit byproducts (FB) involves quantitative and qualitative changes in the tannins, which would consequently change the rumen fermentation characteristics. This study aimed to evaluate whether ensiled FBs are effective in mitigating methane emission from ruminants by conducting in vitro assessments. Methods: Fruit byproducts (grape pomace, wild grape pomace, and persimmon skin) were collected and subjected to four-week ensiling by Lactobacillus buchneri inoculant. A defined feed component with or without FB samples (both fresh and ensiled material) were subjected to in vitro anaerobic culturing using rumen fluid sampled from beef cattle, and the fermentation parameters and microbial populations were monitored. Results: Reduced methane production and a proportional change in total volatile fatty acids (especially enhanced propionate proportion) was noted in bottles containing the FBs compared with that in the control (without FB). In addition, we found lower gene copy number of archaeal 16S rRNA and considerably higher levels of one of the major fibrolytic bacteria (Fibrobacter succinogenes) in the bottles containing FBs than in the control, particularly, when it was included in a forage-based feed. However, in the following cultivation experiment, we observed that FBs failed to exhibit a significant difference in methane production with or without polyethylene glycol, implying that tannins in the FBs may not be responsible for the mitigation of methane generation. Conclusion: The results of the in vitro cultivation experiments indicated that not only the composition but also ensiling of FBs affected rumen fermentation patterns and the degree of methane generation. This is primarily because of the compositional changes in the fibrous fraction during ensiling as well as the presence of readily fermented substrates, whereas tannins in these FBs seemed to have little effect on the ruminal fermentation kinetics.

• Journal of Microbiology and Biotechnology
• /
• v.29 no.7
• /
• pp.1124-1136
• /
• 2019

Salinity is one of the major abiotic stresses that cause reduction of plant growth and crop productivity. It has been reported that plant growth-promoting bacteria (PGPB) could confer abiotic stress tolerance to plants. In a previous study, we screened bacterial strains capable of enhancing plant health under abiotic stresses and identified these strains based on 16s rRNA sequencing analysis. In this study, we investigated the effects of two selected strains, Bacillus aryabhattai H19-1 and B. mesonae H20-5, on responses of tomato plants against salinity stress. As a result, they alleviated decrease in plant growth and chlorophyll content; only strain H19-1 increased carotenoid content compared to that in untreated plants under salinity stress. Strains H19-1 and H20-5 significantly decreased electrolyte leakage, whereas they increased $Ca^{2+}$ content compared to that in the untreated control. Our results also indicated that H20-5-treated plants accumulated significantly higher levels of proline, abscisic acid (ABA), and antioxidant enzyme activities compared to untreated and H19-1-treated plants during salinity stress. Moreover, strain H20-5 upregulated 9-cisepoxycarotenoid dioxygenase 1 (NCED1) and abscisic acid-response element-binding proteins 1 (AREB1) genes, otherwise strain H19-1 downregulated AREB1 in tomato plants after the salinity challenge. These findings demonstrated that strains H19-1 and H20-5 induced ABA-independent and -dependent salinity tolerance, respectively, in tomato plants, therefore these strains can be used as effective bio-fertilizers for sustainable agriculture.

• Microbiology and Biotechnology Letters
• /
• v.46 no.4
• /
• pp.313-319
• /
• 2018

Halophilic lactic acid bacteria (LAB) were isolated from myeolchi-jeotgal (23% NaCl, w/v) fermented in jangdok (Korean earthenware) located outside a house. They were identified as Tetragenococcus halophilus by 16S rRNA and recA gene sequencing. Four T. halophilus isolates showing high protease activities were selected for further studies. Four strains grew well, reaching $OD_{600}$ values of 0.75-0.92 at 18% NaCl content (w/v) and 0.28-0.44 at 23% salt. They showed rapid growth, attaining $OD_{600}$ values of 1.1-1.2 at $20-30^{\circ}C$, but did not grow at $4^{\circ}C$. At $15^{\circ}C$, the highest $OD_{600}$ values, which exceeded 0.6, were observed at 20 days, and were higher than those of cultures at $37^{\circ}C$ and $42^{\circ}C$ (approximately 0.5). Four isolates grew best in broth where the initial pH was adjusted to 8 and did not grow at $pH{\leq}4$. T. halophilus BS2-36 showed the highest survival ratio of 18.7% after 2 hours of exposure at pH 3. BS2-36 showed the highest survival ratio (1.29%) in presence of 0.3% bile salts. T. halophilus BS2-36 seems a promising candidate as a starter for jeotgal and other fermented foods with high salinities.

• The Plant Pathology Journal
• /
• v.35 no.2
• /
• pp.178-187
• /
• 2019

Plants are exposed to biotic stresses caused by pathogen attack and complex abiotic stresses including heat and drought by dynamic climate changes. To alleviate these stresses, we investigated two bacterial stains, H26-2 and H30-3 in two cultivars ('Ryeokkwang' and 'Buram-3-ho') of Chinese cabbage in plastic pots in a greenhouse. We evaluated effects of bacterial strains on plant growth-promotion and mitigation of heat and drought stresses; the role of exopolysaccharides as one of bacterial determinants on alleviating stresses; biocontrol activity against soft rot caused by Pectobacterium carotovorum subsp. carotovorum PCC21. Strains H26-2 and H30-3 significantly increased fresh weights compared to a $MgSO_4$ solution; reduced leaf wilting and promoted recovery after re-watering under heat and drought stresses. Chinese cabbages treated with H26-2 and H30-3 increased leaf abscisic acid (ABA) content and reduced stomatal opening after stresses treatments, in addition, these strains stably colonized and maintained their populations in rhizosphere during heat and drought stresses. As well as tested bacterial cells, exopolysaccharides (EPS) of H30-3 could be one of bacterial determinants for alleviation of tested stresses in Chinese cabbages, however, the effects were different to cultivars of Chinese cabbages. In addition to bacterial activity to abiotic stresses, H30-3 could suppress incidence (%) of soft rot in 'Buram-3-ho'. The tested strains were identified as Bacillus aryabhattai H26-2 and B. siamensis H30-3 based on 16S rRNA gene sequence analysis. Taken together, H26-2 and H30-3 could be candidates for both plant growth promotion and mitigation of heat and drought stresses in Chinese cabbage.

• Asian-Australasian Journal of Animal Sciences
• /
• v.32 no.1
• /
• pp.82-91
• /
• 2019

Objective: This experiment was conducted to compare the structure and composition of ruminal microorganisms in goats with high and low neutral detergent fibre (NDF) digestibility. Methods: Nineteen crossbred goats were used as experimental animals and fed the same total mixed rations during the 30-day pre-treatment and 6-day digestion trialperiods. All faeces were collected during the digestion period for measuring the NDF digestibility. Then, high and the low NDF digestibility individuals were chosen for the high NDF digestibility group (HFD) and low NDF digestibility group (LFD), respectively. Rumen contents were collected for total microbial DNA extraction. The V4 region of the bacterial 16S rRNA gene was amplified using universal primers of bacteria and sequenced using high-throughput sequencer. The sequences were mainly analysed by QIIME 1.8.0. Results: A total of 18,694 operational taxonomic units were obtained, within 81.98% belonged to bacteria, 6.64% belonged to archaea and 11.38% was unassigned microorganisms. Bacteroidetes, Firmicutes, and Proteobacteria were the predominant microbial phyla in both groups. At the genus level, the relative abundance of fifteen microorganisms were significantly higher (p<0.05) and six microorganisms were extremely significantly higher (p<0.01) in LFD than HFD. Overall, 176 core shared genera were identified in the two groups. The relative abundance of 2 phyla, 5 classes, 10 orders, 13 families and 15 genera had a negative correlation with NDF digestibility, but only the relative abundance of Pyramidobacter had a positive correlation with NDF digestibility. Conclusion: There were substantial differences in NDF digestibility among the individual goats, and the NDF digestibility had significant correlation with the relative abundance of some ruminal microorganisms.

• Microbiology and Biotechnology Letters
• /
• v.47 no.3
• /
• pp.441-448
• /
• 2019

This study was aimed at identifying the lower airway microbiota in patients with lung cancer (LC) using protected brush sampling. We enrolled 37 patients undergoing diagnostic bronchoscopy for suspected LC, 26 with LC and 11 with benign diseases. Protected brush specimens were obtained from the contralateral lung and the side of the tumor; these specimens were analyzed by 16S rRNA-based-next-generation sequencing. The results indicated that the biodiversity was not different between groups, and there were no significant differences between the proportion of microorganisms in the tumor and in the contralateral side of patients with LC. In patients with LC, there was a higher abundance of several microorganisms including Capnocytophaga, Haemophilus, Enterococcus, and Streptococcus; whereas, in individuals without LC, Bacteroides, Lactobacillus, or Methylobacterium were more abundant. Malignancy could be determined with an accuracy of 70% by isolating Enterococcus, Capnocytophaga, or Actinomyces. Microbispora indicated benignity with a sensitivity of 55%, specificity of 88%, and accuracy of 78%. Lower airway microbiota in patients with LC is fairly similar in both the tumor and contralateral sites. Endobronchial microbiota is different in patients with and without LC, and these differences may have a potential clinical value as diagnostic or prognostic biomarkers.

• Microbiology and Biotechnology Letters
• /
• v.47 no.1
• /
• pp.105-115
• /
• 2019

Saline or alkaline condition in soil inhibits growth of most crop plants and limits crop yields in many parts of the world. Augmenting an alkaline soil with alkali-tolerant bacteria capable of promoting plant growth can be a promising approach in expanding fertile agricultural land. Near-shore environments of Dokdo Island, a remote island located in the middle of the East Sea, appear to have patches of seawater-influenced haloalkaline soil that is unsupportive for growth of conventional plants. To exploit metabolic capacities of alkali-tolerant bacteria for promoting plant growth in saline or alkaline soils, we isolated of alkali-tolerant bacteria from near-shore soil samples in Dokdo and investigated properties of the isolates. Alkali-tolerant bacteria were selectively cultivated by inoculating suspended and diluted soil samples on a plate medium adjusted to pH 10. Fifty colonies were identified based on their $GTG_5$-PCR genomic fingerprints and 16S rRNA gene sequences. Most isolates were affiliated to alkali-tolerant and/or halotolerant genera or species of the phyla Firmicutes (68%), Proteobacteria (30%) and Actinobacteria (2%). Unlike the typical soil bacterial flora in the island, alkali-tolerant isolates belonged to only certain taxa of terrestrial origin under the three phyla, which have traits of plant growth promoting activities including detoxification, phytohormone production, disease/pest control, nitrogen-fixation, phosphate solubilization or siderophore production. However, Firmicutes of marine origin generally dominated the alkali-tolerant community. Results of this study suggest that haloalkaline environments like Dokdo shore soils are important sources for plant growth promoting bacteria that can be employed in bio-augmentation of vegetation-poor alkaline soils.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.52 no.1
• /
• pp.67-73
• /
• 2019

We presented detailed morphological descriptions of the eggs, larvae and juvenile of Acanthaphritis unoorum based on specimens collected with bongo nets from Korean waters during the period May 2017-July 2018. We collected 18 individuals including eggs (n= 4, 0.77-0.85 mm in egg diameter), preflexion larvae (n= 6, 4.11-6.31 mm in standard length, SL), flexion larvae (n= 4, 6.60-7.82 mm SL), postflexion larvae (n= 3, 8.94-13.46 mm SL), and one juvenile (n= 1, 14.67 mm SL). The mitochondrial (mt) DNA 16S rRNA sequences of the eggs, and the cytochrome c oxidase subunit I (COI) sequences of the larvae were identical to those of A. unoorum adults (genetic distances <0.01). The A. unoorum larvae and the juvenile that we collected were morphologically similar to those of Dactylopsaron dimorphicum, but the A. unoorum specimens were readily distinguishable by the presence of lateral melanophores. This is the first record of A. unoorum in Korean waters. We propose a new Korean name for A. unoorum: "O-ri-bu-ri-nuntung-i".

• Journal of Microbiology and Biotechnology
• /
• v.29 no.1
• /
• pp.79-90
• /
• 2019

Lichens are generally known as self-sufficient, symbiotic life-forms between fungi and algae/cyanobacteria, and they also provide shelter for a wide range of beneficial bacteria. Currently, bacterial-derived biodegradable polyhydroxyalkanoate (PHA) is grabbing the attention of many researchers as a promising alternative to non-degradable plastics. This study was conducted to develop a new method of PHA production using unexplored lichen-associated bacteria, which can simultaneously degrade two ubiquitous industrial toxins, anthracene and naphthalene. Here, 49 lichen-associated bacteria were isolated and tested for PHA synthesis. During the GC-MS analysis, a potential strain of EL19 was found to be a 3-hydroxyhexanoate (3-HHx) accumulator and identified as Pseudomonas sp. based on the 16S rRNA sequencing. GC analysis revealed that EL19 was capable of accumulating 30.62% and 19.63% of 3-HHx from naphthalene and anthracene, respectively, resulting in significant degradation of 98% and 96% of naphthalene and anthracene, respectively, within seven days. Moreover, the highly expressed phaC gene verified the genetic basis of $PHA_{mcl}$ production under nitrogen starvation conditions. Thus, this study strongly supports the hypothesis that lichen-associated bacteria can detoxify naphthalene and anthracene, store energy for extreme conditions, and probably help the associated lichen to live in extreme conditions. So far, this is the first investigation of lichen-associated bacteria that might utilize harmful toxins as feasible supplements and convert anthracene and naphthalene into eco-friendly 3-HHx. Implementation of the developed method would reduce the production cost of $PHA_{mcl}$ while removing harmful waste products from the environment.