Publications

3976

ABSTRACT A mesophilic filamentous anoxygenic phototrophic bacterium, designated M50-1, was isolated from a microbial mat of the Chukhyn Nur soda lake (northeastern Mongolia) with salinity of 5−14 g/L and pH 8.0−9.3. The organism is a strictly anaerobic phototrophic bacterium, which required sulfide for phototrophic growth. The cells formed short undulate trichomes surrounded by a thin sheath and containing gas vesicles. Motility of the trichomes was not observed. The cells contained chlorosomes. The antenna pigments were bacteriochlorophyll d and β- and γ-carotenes. Analysis of the genome assembled from the metagenome of the enrichment culture revealed all the enzymes of the 3-hydroxypropionate bi-cycle for autotrophic CO2 assimilation. The genome also contained the genes encoding a type IV sulfide:quinone oxidoreductase (sqrX). The organism had no nifHDBK genes, encoding the proteins of the nitrogenase complex responsible for dinitrogen fixation. The DNA G + C content was 58.6%. The values for in silico DNA‒DNA hybridization and average nucleotide identity between M50-1 and a closely related bacterium ‘Ca. Chloroploca asiatica’ B7-9 containing bacteriochlorophyll c were 53.4% and 94.0%, respectively, which corresponds to interspecies differences. Classification of the filamentous anoxygenic phototrophic bacterium M50-1 as a new ‘Ca. Chloroploca’ species was proposed, with the species name ‘Candidatus Chloroploca mongolica’ sp. nov.

Abstract A new distribution map is provided for Candidatus Liberibacter asiaticus Jagoueix et al. Alphaproteobacteria: Rhizobiales: Rhizobiaceae. Hosts: Citrus spp. Information is given on the geographical distribution in Africa (Egypt, Ethiopia, Kenya, Mauritius, Réunion, Tanzania, Uganda), Asia (Bangladesh, Bhutan, Borneo, Cambodia, China, Fujian, Guangdong, Guangxi, Guizhou, Hainan, Hunan, Jiangxi, Sichuan, Yunnan, Zhejiang, Hong Kong, India, Andhra Pradesh, Arunachal Pradesh, Assam, Bihar, Delhi, Gujarat, Haryana, Himachal Pradesh, Jammu and Kashmir, Karnataka, Kerala, Madhya Pradesh, Maharashtra, Manipur, Meghalaya, Mizoram, Nagaland, Odisha, Punjab, Rajasthan, Sikkim, Tamil Nadu, Tripura, Uttar Pradesh, Uttarakhand, West Bengal, Indonesia, Java, Lesser Sunda Islands, Provinsi Papua, Sulawesi, Sumatra, Iran, Japan, Kyushu, Ryukyu Islands, Laos, Malaysia, Peninsular Malaysia, Sarawak, Myanmar, Nepal, Oman, Pakistan, Philippines, Saudi Arabia, Sri Lanka, Taiwan, Thailand, Vietnam, Yemen), North America (Barbados, Belize, Costa Rica, Cuba, Dominica, Dominican Republic, Guadeloupe, Guatemala, Honduras, Jamaica, Martinique, Mexico, Nicaragua, Panama, Puerto Rico, Trinidad and Tobago, Unites States Virgin Islands, USA, Alabama, California, Florida, Georgia, Louisiana, South Carolina, Texas), Oceania (Papua New Guinea, Timor Leste), South America (Argentina, Brazil, Bahia, Minas Gerais, Paraná, São Paulo, Colombia, Paraguay, Venezuela).

SummaryCandidatus Dormibacterota is an uncultured bacterial phylum found predominantly in soil that is present in high abundances within cold desert soils. Here, we interrogate nine metagenome‐assembled genomes (MAGs), including six new MAGs derived from soil metagenomes obtained from two eastern Antarctic sites. Phylogenomic and taxonomic analyses revealed these MAGs represent four genera and five species, representing two order‐level clades within Ca. Dormibacterota. Metabolic reconstructions of these MAGs revealed the potential for aerobic metabolism, and versatile adaptations enabling persistence in the ‘extreme’ Antarctic environment. Primary amongst these adaptations were abilities to scavenge atmospheric H2 and CO as energy sources, as well as using the energy derived from H2 oxidation to fix atmospheric CO2 via the Calvin–Bassham–Benson cycle, using a RuBisCO type IE. We propose that these allow Ca. Dormibacterota to persist using H2 oxidation and grow using atmospheric chemosynthesis in terrestrial Antarctica. Fluorescence in situ hybridization revealed Ca. Dormibacterota to be coccoid cells, 0.3–1.4 μm in diameter, with some cells exhibiting the potential for a symbiotic or syntrophic lifestyle.

SummaryWe report on the genomic characterization of three novel classes in the phylum Desulfobacterota. One class (proposed name Candidatus ‘Anaeroferrophillalia’) was characterized by heterotrophic growth capacity, either fermentatively or utilizing polysulfide, tetrathionate or thiosulfate as electron acceptors. In the absence of organic carbon sources, autotrophic growth via the Wood–Ljungdahl (WL) pathway and using hydrogen or Fe(II) as an electron donor is also inferred for members of the ‘Anaeroferrophillalia’. The second class (proposed name Candidatus ‘Anaeropigmentia’) was characterized by its capacity for growth at low oxygen concentration, and the capacity to synthesize the methyl/alkyl carrier CoM, an ability that is prevalent in the archaeal but rare in the bacterial domain. Pigmentation is inferred from the capacity for carotenoid (lycopene) production. The third class (proposed name Candidatus ‘Zymogenia’) was characterized by fermentative heterotrophic growth capacity, broad substrate range and the adaptation of some of its members to hypersaline habitats. Analysis of the distribution pattern of all three classes showed their occurrence as rare community members in multiple habitats, with preferences for anaerobic terrestrial, freshwater and marine environments over oxygenated (e.g. pelagic ocean and agricultural land) settings. Special preference for some members of the class Candidatus ‘Zymogenia’ for hypersaline environments such as hypersaline microbial mats and lagoons was observed.