Publications

4475

The Asian citrus psyllid, Diaphorina citri, is the vector of the bacterium “Candidatus Liberibacter asiaticus” (Las), associated with the devastating, worldwide citrus disease huanglongbing. In order to explore the molecular interactions of this bacterium with D. citri during the vector acquisition process, cDNA libraries were sequenced on an Illumina platform, obtained from the gut of adult psyllids confined in healthy (H) and in Las-infected young shoots (Las) for different periods of times (I = 1/2 days, II = 3/4 days, and III = 5/6 days). In each sampling time, three biological replicates were collected, containing 100 guts each, totaling 18 libraries depleted in ribosomal RNA. Reads were quality-filtered and mapped against the Chinese JXGC Las strain and the Floridian strain UF506 for the analysis of the activity of Las genome and SC1, SC2, and type 3 (P-JXGC-3) prophages of the studied Las strain. Gene activity was considered only if reads of at least two replicates for each acquisition access period mapped against the selected genomes, which resulted in coverages of 44.4, 79.9, and 94.5% of the JXGC predicted coding sequences in Las I, Las II, and Las III, respectively. These genes indicate an active metabolism and increased expression according to the feeding time in the following functional categories: energy production, amino acid metabolism, signal translation, cell wall, and replication and repair of genetic material. Pilins were among the most highly expressed genes regardless of the acquisition time, while only a few genes from cluster I of flagella were not expressed. Furthermore, the prophage region had a greater coverage of reads for SC1 and P-JXGC-3 prophages and low coverage in SC2 and no indication of activity for the lysis cycle. This research presents the first descriptive analysis of Las transcriptome in the initial steps of the D. citri gut colonization, where 95% of Las genes were active.

Anoxygenic phototrophic bacteria can be important primary producers in some meromictic lakes. Green sulfur bacteria (GSB) have been detected in ferruginous lakes, with some evidence that they are photosynthesizing using Fe(II) as an electron donor (i.e., photoferrotrophy). However, some photoferrotrophic GSB can also utilize reduced sulfur compounds, complicating the interpretation of Fe-dependent photosynthetic primary productivity. An enrichment (BLA1) from meromictic ferruginous Brownie Lake, Minnesota, United States, contains an Fe(II)-oxidizing GSB and a metabolically flexible putative Fe(III)-reducing anaerobe. “CandidatusChlorobium masyuteum” grows photoautotrophically with Fe(II) and possesses the putative Fe(II) oxidase-encodingcyc2gene also known from oxygen-dependent Fe(II)-oxidizing bacteria. It lacks genes for oxidation of reduced sulfur compounds. Its genome encodes for hydrogenases and a reverse TCA cycle that may allow it to utilize H2and acetate as electron donors, an inference supported by the abundance of this organism when the enrichment was supplied by these substrates and light. The anaerobe “CandidatusPseudopelobacter ferreus” is in low abundance (∼1%) in BLA1 and is a putative Fe(III)-reducing bacterium from theGeobacteralesord. nov. While “Ca.C. masyuteum” is closely related to the photoferrotrophsC. ferroooxidansstrain KoFox andC. phaeoferrooxidansstrain KB01, it is unique at the genomic level. The main light-harvesting molecule was identified as bacteriochlorophyllcwith accessory carotenoids of the chlorobactene series. BLA1 optimally oxidizes Fe(II) at a pH of 6.8, and the rate of Fe(II) oxidation was 0.63 ± 0.069 mmol day–1, comparable to other photoferrotrophic GSB cultures or enrichments. Investigation of BLA1 expands the genetic basis for phototrophic Fe(II) oxidation by GSB and highlights the role these organisms may play in Fe(II) oxidation and carbon cycling in ferruginous lakes.

AbstractCandidate phyla radiations (CPR), accounting for a major microbial supergroup with remarkably small genomes and reduced sizes, are widely distributed yet mostly uncultured. Limited culture and its obligate reliance upon other bacteria hindered investigation of their lifestyles. In this work we isolated a CPR bacterium, TM7i, with its host Leucobacter aridocollis J1, by combination of Emulsion, Paired Isolation and Concatenation PCR (epicPCR) detection and filtrate co-culture. Genomic profiling of TM7 genomes and microscopic investigation of TM7i-J1 symbiosis suggest the conservation of type IV pili and a pili-dependent lifestyle of TM7. Further, we observed twitching motility of TM7i mediated by pili and its role played in the interaction with its host. Our results shed a light on the lifestyle about this enigmatic bacterial radiation, which may also be adopted by other CPR organisms. The epicPCR-directed isolation method underlines high efficiency of CPR bacteria isolation and thus may be used in other symbiotic or epibiotic microorganisms.

Bactericera cockerelli es una plaga de importancia económica en solanáceas en México, por los amarillamientos que causa en los cultivos, así como por la transmisión de Candidatus Liberibacter solanacearum. Se describen variantes genéticas de este insecto, las cuales se relacionan con su capacidad para fungir como vector. En México, la distribución de B. cockerelli es muy amplia y se carece de información acerca de sus características morfológicas y genéticas. El objetivo de esta investigación fue caracterizar morfológica y genéticamente a B. cockerelli y detectar la presencia de Ca. L. solanacearum en poblaciones de B. cockerelli de las zonas productoras de solanáceas en México. Para lo cual se muestrearon 35 localidades de 13 estados, sobre cultivos de chile, tomate, berenjena y papa, bajo diferentes sistemas de producción. Se midieron las variables largas de cuerpo (LC), largas de abdomen (LAB) y ancho de abdomen (AAB) en insectos de cada población, se detectó la presencia de Ca. L. solanacearum en los 13 estados muestreados, donde los machos presentaron el mayor porcentaje de insectos positivos. La presencia de Ca. L. solanacearum no se vio influenciada por el hospedero o el sistema de producción, sino por la presencia de B. cockerelli.

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).