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3 "Dictyostelium"
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RapB Regulates Cell Adhesion and Migration in Dictyostelium, Similar to RapA.
Uri Han, Nara Han, Byeonggyu Park, Taeck Joong Jeon
J. Microbiol. 2024;62(8):627-637.   Published online June 17, 2024
DOI: https://doi.org/10.1007/s12275-024-00143-y
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AbstractAbstract
Ras small GTPases act as molecular switches in various cellular signaling pathways, including cell migration, proliferation, and differentiation. Three Rap proteins are present in Dictyostelium; RapA, RapB, and RapC. RapA and RapC have been reported to have opposing functions in the control of cell adhesion and migration. Here, we investigated the role of RapB, a member of the Ras GTPase subfamily in Dictyostelium, focusing on its involvement in cell adhesion, migration, and developmental processes. This study revealed that RapB, similar to RapA, played a crucial role in regulating cell morphology, adhesion, and migration. rapB null cells, which were generated by CRISPR/Cas9 gene editing, displayed altered cell size, reduced cell-substrate adhesion, and increased migration speed during chemotaxis. These phenotypes of rapB null cells were restored by the expression of RapB and RapA, but not RapC. Consistent with these results, RapB, similar to RapA, failed to rescue the phenotypes of rapC null cells, spread morphology, increased cell adhesion, and decreased migration speed during chemotaxis. Multicellular development of rapB null cells remained unaffected. These results suggest that RapB is involved in controlling cell morphology and cell adhesion. Importantly, RapB appears to play an inhibitory role in regulating the migration speed during chemotaxis, possibly by controlling cell-substrate adhesion, resembling the functions of RapA. These findings contribute to the understanding of the functional relationships among Ras subfamily proteins.
Sporosarcina jeotgali sp. nov., Sporosarcina oncorhynchi sp. nov., and Sporosarcina trichiuri sp. nov., Isolated from Jeotgal, a Traditional Korean Fermented Seafood.
Ah-In Yang, Bora Kim, Sung-Hong Joe, Hae-In Joe, Hanna Choe, Ki Hyun Kim, Min Ok Jun, Na-Ri Shin
J. Microbiol. 2024;62(4):285-296.   Published online April 8, 2024
DOI: https://doi.org/10.1007/s12275-024-00106-3
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AbstractAbstract
Three novel, Gram-stain-positive, obligate aerobic, catalase- and oxidase-positive bacterial strains, designated B2O-1(T), T2O-4(T), and 0.2-SM1T-5(T), were isolated from jeotgal, a traditional Korean fermented seafood. Strains B2O-1(T), T2O-4(T), and 0.2-SM1T-5(T) exhibited distinct colony colors, characterized by pink, yellow, and red opaque circular colonies, respectively. Phylogenetic analysis revealed that three strains formed a paraphyletic clade within the genus Sporosarcina and shared < 99.0% similarity with Sporosarcina aquimarina KCTC 3840(T) and Sporosarcina saromensis KCTC 13119(T) in their 16S rRNA gene sequences. The three strains exhibiting Orthologous Average Nucleotide Identity values < 79.3% and digital DNA-DNA hybridization values < 23.1% within the genus Sporosarcina affirmed their distinctiveness. Strains B2O-1(T), T2O-4(T), and 0.2-SM1T-5(T) contained MK-7 as a sole respiratory menaquinone and A4α type peptidoglycan based on lysine with alanine, glutamic acid, and aspartic acid. The common polar lipids include diphosphatidylglycerol, phosphatidylglycerol, and phosphatidylethanolamine. Strain T2O-4(T) contained one unidentified phospholipid, whereas strain 0.2-SM1T-5(T) contained two unidentified phospholipids. Cellular fatty acid profiles, with C(15:0) anteiso as the major fatty acid, supported the affiliation of the three strains to the genus Sporosarcina. Based on the polyphasic characteristics, strains B2O-1(T) (= KCTC 43506(T) = JCM 36032(T)), T2O-4(T) (= KCTC 43489(T) = JCM 36031(T)), and 0.2-SM1T-5(T) (= KCTC 43519(T) = JCM 36034(T)) represent three novel species within the genus Sporosarcina, named Sporosarcina jeotgali sp. nov., Sporosarcina oncorhynchi sp. nov., and Sporosarcina trichiuri sp. nov., respectively.
Variations of microbial community in Aconitum carmichaeli Debx. rhizosphere soilin a short-term continuous cropping system
Xia Fei , Wang Lina , Chen Jiayang , Fu Meng , Wang Guodong , Yan Yaping , Cui Langjun
J. Microbiol. 2021;59(5):481-490.   Published online March 29, 2021
DOI: https://doi.org/10.1007/s12275-021-0515-z
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AbstractAbstract
Aconitum carmichaeli Debx. (Ranunculaceae) is a potential source of an important herbal drug named “Fuzi”, which is derived from the lateral root of the plant. Increased therapeutic usage resulted in the great demand for artificial cultivation of A. carmichaeli, however, the obstacles caused by continuous cropping is a serious problem. Continuous cropping has shown to affect the soil biological and non-biological factors. The current study attempted to discover the variations of microbial communities and soil properties in shortterm continuous cropping of A. carmichaeli. An experimental procedure with A. carmichaeli planted two years continuously was established. The variation of the soil microbial community, disease incidence, soil properties, and the correlation between soil microbe and disease incidence were investigated. The disease incidence increased during the continuous cropping of A. carmichaeli. The PCoA and LefSe results indicated that fungal communities in rhizosphere soil were altered during the short-term continuous croppingand the bacterial community was disturbed by the cultivation of A. carmichaeli, however, in the following two years of continuous cropping period, the soil bacterial community has not changed obviously. Proportions of some fungal and bacterial genera were varied significantly (p < 0.05), and some genera of microflora showed a significant correlation with adisease incidence of A. carmichaeli. Microorganisms contributing to community composition discrepancy were also elucidated. Continuous cropping of A. carmichaeli disturbed the rhizosphere soil microbial community and altered the soil chemical parameters and soil pH. These variations in soil may be related to the occurrence of plant diseases. The current study will not only provide theoretical and experimental evidence for the A. carmichaeli continuous cropping obstacles but will also contribute to A. carmichaeli agricultural production and soil improvement.

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