• Journal of Microbiology and Biotechnology
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• v.32 no.3
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• pp.294-301
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• 2022

In our greenhouse experiment, soil heat treatment groups (50, 80, and 121℃) significantly promoted growth and disease suppression of Panax notoginseng in consecutively cultivated soil (CCS) samples (p < 0.01), and 80℃ worked better than 50℃ and 121℃ (p < 0.01). Furthermore, we found that heat treatment at 80℃ changes the microbial diversity in CCS, and the inhibition ratios of culturable microorganisms, such as fungi and actinomycetes, were nearly 100%. However, the heat-tolerant bacterial community was preserved. The 16S rRNA gene and internal transcribed spacer (ITS) sequencing analyses indicated that the soil heat treatment had a greater effect on the Chao1 index and Shannon's diversity index of bacteria than fungi, and the relative abundances of Firmicutes and Proteobacteria were significantly higher than without heating (80 and 121℃, p < 0.05). Soil probiotic bacteria, such as Bacillus (67%), Sporosarcina (9%), Paenibacillus (6%), Paenisporosarcina (6%), and Cohnella (4%), remained in the soil after the 80℃ and 121℃ heat treatments. Although steam increased the relative abundances of most of the heat-tolerant microbes before sowing, richness and diversity gradually recovered to the level of CCS, regardless of fungi or bacteria, after replanting. Thus, we added heat-tolerant microbes (such as Bacillus) after steaming, which reduced the relative abundance of pathogens, recruited antagonistic bacteria, and provided a long-term protective effect compared to the steaming and Bacillus alone (p < 0.05). Taken together, the current study provides novel insight into sustainable agriculture in a consecutively cultivated system.

• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.7
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• pp.1115-1124
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• 2013

The present study was conducted to ensure the diversity of domestic solar salt by analyzing the composition and microbiological characteristics of solar salt (from Docho island: DS) and the flower of salt produced in different Korean salt flats (Sinui island: SF, Bigum island: BF, and Docho island: DF). The analyses showed that the moisture content of the three types of flower of salt and solar salt ranged from 10.54~13.82% and NaCl content ranged from 78.81~84.61%. The mineral content of those salts ranged from 3.57~5.51%. The content of insoluble matter in these salts was $0.01{\pm}0.00{\sim}0.05{\pm}0.00%$. The sand content of these salts was $0.01{\pm}0.01{\sim}0.03{\pm}0.01%$. By Hunter's color value analysis, the color of the flower of salt was brighter and whiter than solar salt. The salinity of the flower of salt was a little higher than solar salt as well. The magnesium and potassium ion content of DF was $9,886.72{\pm}104.78mg/kg$ and $2,975.23{\pm}79.73mg/kg$, respectively, which was lower than the content in SF, BF, and DS. The heavy metal content of all salts was acceptable under the Korean Food Sanitation Law. The flower of salt was confirmed to be sweeter and preferable to solar salt. More than 80% of the solar salt crystals were 2~3 mm in size, whereas crystals from the flower of salt were 0.5~2 mm in size. The bacterial diversity of DF and DS were investigated by culture and denaturing gradient gel electrophoresis (DGGE) methods. The number of cultured bacteria in flower of salt was approximately three times more than solar salt. By DGGE analysis, major microbes of DF were Maritimibacter sp., Cupriavidus sp., and unculturable bacteria, and those of DS were Cupriavidus sp., Dunalidella salina and unculturable bacteria. The results of DGGE analysis showed that major microorganisms in solar salts were composed of unidentified and unculturable bacteria and only a few microorganisms were culturable.

• Applied Biological Chemistry
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• v.50 no.4
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• pp.268-275
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• 2007

Diversity of the mud flat microbial population in Suncheon Bay was investigated by studying extracellular enzyme activities and 16S rDNA sequences. Four culturable bacterial strains with CMCase, xylanase and protease activities were isolated from the wetland and the mud flat. All the strains produced more xylanase activity than CMCase or protease activity, and the properties of the isolate enzymes from the wetland were similar to those from the mud flat. About 2,000 clones were obtained with the 16S rDNA amplified from the metagenomic DNA isolated from the mud samples. Based on the restriction pattern(s), seventeen clones were selected for base sequence analysis. Of the 17 clones, only 35% (6 clones) were found to be cultured strains and 65% (11 clones) to be uncultured strains. The similarities in the base sequences of the clones ranged from 91.0% to 99.9% with an average similarity of 97.3%. The clones could be divided into 7 groups, Proteobacteria (9 clones, 52.9%), Firmicutes (3 clones, 17.6%), Bacteroidetes (1 clone), Flavobacteria (1 clone), Verrucomicrobia (1 clone), Acidobacteria (1 clone), and Chloroflexi (1 clone). Most of the Proteobacteria clones were gamma Proteobacteria associated with oxidation-reduction of sulfur.