The "beauty in the beast"-the multiple uses of Priestia megaterium in biotechnology.

Over 30 years, the Gram-positive bacterium Priestia megaterium (previously known as Bacillus megaterium) was systematically developed for biotechnological applications ranging from the production of small molecules like vitamin B12, over polymers like polyhydroxybutyrate (PHB) up to the in vivo and in vitro synthesis of multiple proteins and finally whole-cell applications. Here we describe the use of the natural vitamin B12 (cobalamin) producer P. megaterium for the elucidation of the biosynthetic pathway and the subsequent systematic knowledge-based development for production purposes. The formation of PHB, a natural product of P. megaterium and potential petro-plastic substitute, is covered and discussed. Further important biotechnological characteristics of P. megaterium for recombinant protein production including high protein secretion capacity and simple cultivation on value-added carbon sources are outlined. This includes the advanced system with almost 30 commercially available expression vectors for the intracellular and extracellular production of recombinant proteins at the g/L scale. We also revealed a novel P. megaterium transcription-translation system as a complementary and versatile biotechnological tool kit. As an impressive biotechnology application, the formation of various cytochrome P450 is also critically highlighted. Finally, whole cellular applications in plant protection are completing the overall picture of P. megaterium as a versatile giant cell factory. KEY POINTS: • The use of Priestia megaterium for the biosynthesis of small molecules and recombinant proteins through to whole-cell applications is reviewed. • P. megaterium can act as a promising alternative host in biotechnological production processes.

Rhizobium panacihumi sp. nov., an isolate from ginseng-cultivated soil, as a potential plant growth promoting bacterium.

A novel bacterial strain designated DCY116T was isolated from ginseng-cultivated soil in Gochang-gun, Republic of Korea. Strain DCY116T, belongs to the genus Rhizobium, and is closely related to Rhizobium yantingense H66T (98.3%), Neorhizobium huautlense S02T (98.2%), Rhizobium soli DS-42T (98.1%), Rhizobium smilacinae PTYR-5T (97.9%), and Neorhizobium alkalisoli CCBAU 01393T (97.9%) based on 16S rRNA gene sequence analysis. Analysis of the housekeeping genes atpD, recA, and glnII showed low levels of sequence similarity (96.8%) between strain DCY116T and other closely related species. Strain DCY116T was Gram-stain negative, motile by peritrichous flagella, rod-shaped, strictly aerobic, catalase- and oxidase-positive. Q-10 was the predominant ubiquinone. The major cellular fatty acids were identified as C16:0 and summed feature 8 (C18:1 ω7c and/or C18:1 ω6c). The major polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, and an unknown lipid (L1-3). Genomic DNA G + C content of strain DCY116T was determined to be 57.2 mol%. DNA-DNA homology values between strain DCY116T and closely related species of the genus Rhizobium were lower than 40%. Strain DCY116T produced indole-3-acetic acid, siderophores, and was able to solubilize phosphate as a potential plant growth promoting bacterium. In conclusion, the results of this study support strain DCY116T as a novel species of the genus Rhizobium, for which the name Rhizobium panacihumi is proposed. The type strain is DCY116T (= KCTC 62017T = JCM 32251T).

Paenibacillus panacihumi sp. nov., a potential plant growth-promoting bacterium isolated from ginseng-cultivated soil.

A novel bacterium, designated DCY114T, was isolated from ginseng-cultivated soil in Gochang-gun, Republic of Korea. This isolate was assigned to the genus Paenibacillus and is closely related to Paenibacillus amylolyticus NRRL NRS-290T (98.3%), P. dongdonensis KUDC0114T (98.0%), P. tylopili MK2T (97.9%), P. tundrae A10bT (97.8%), and P. xylanexedens B22aT (97.5%) based on 16S rRNA gene sequence analysis. Strain DCY114T is a Gram-reaction positive, catalase and oxidase positive, facultatively aerobic rod that is motile by peritrichous flagella. Strain DCY114T produces siderophores and indole-3-acetic acid (IAA) and is able to solubilize phosphate as a plant growth-promoting bacterium. MK-7 was the diagnostic menaquinone. The major cellular fatty acids were anteiso-C15:0, C16:0, and C18:0, and the major polar lipids were diphosphatidylglycerol (DPG), phosphatidylethanolamine (PE), and an unknown amino lipid (AL1,2). The genomic DNA G + C content was 46.0 mol%. Phenotypic and chemotaxonomic results also placed strain DCY114T within the genus Paenibacillus. DNA-DNA homology values between strain DCY114T and closely related reference strains were lower than 43%. The low DNA relatedness data in combination with phylogenetic and biochemical tests indicated that strain DCY114T could not be assigned to a recognized species. The results of this study support that the DCY114T strain is a novel species belonging to the genus Paenibacillus, for which the name Paenibacillus panacihumi is proposed. The type strain is DCY114T (= KCTC 33915T = JCM 32073T).