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Jihong Jiang – 1st expert on this subject based on the ideXlab platform

  • carbonate mineral formation under the influence of limestone colonizing Actinobacteria morphology and polymorphism
    Frontiers in Microbiology, 2016
    Co-Authors: Jihong Jiang, Ying Huang, Bin Lian


    Microorganisms and their biomineralisation processes are widespread in almost every environment on earth. In this work, Streptomyces luteogriseus DHS C014, a dominant lithophilous Actinobacteria isolated from microbial mats on limestone rocks, was used to investigate its potential biomineralisation to allow a better understanding of bacterial contributions to carbonate mineralisation in nature. The ammonium carbonate free-drift method was used with mycelium pellets, culture supernatant, and spent culture of the strain. Mineralogical analyses showed that hexagonal prism calcite was only observed in the sub-surfaces of the mycelium pellets, which is a novel morphology mediated by microbes. Hemispheroidal vaterite appeared in the presence of spent culture, mainly because of the effects of soluble microbial products (SMP) during mineralisation. When using the liquid culture, doughnut-like vaterite was favoured by Actinobacterial mycelia, which has not yet been captured in previous studies. Our analyses suggested that the effects of mycelium pellets as a molecular template almost gained an advantage over SMP both in crystal nucleation and growth, having nothing to do with biological activity. It is thereby convinced that lithophilous Actinobacteria, S. luteogriseus DHS C014, owing to its advantageous genetic metabolism and filamentous structure, showed good biomineralisation abilities, maybe it would have geoactive potential for biogenic carbonate in local microenvironments.

  • biodiversity and plant growth promoting traits of culturable endophytic Actinobacteria associated with jatropha curcas l growing in panxi dry hot valley soil
    Applied Soil Ecology, 2015
    Co-Authors: Qian Miao, Weiwei Feng, Yu Wang, Ke Xing, Jihong Jiang


    Abstract One of the proposed mechanisms through which plant growth-promoting endophyte (PGPE) enhances plant growth is the production of 1-aminocyclopropane-1-carboxylic acid deaminase (ACCD). However, information about the endophytic Actinobacteria with ACC deaminase activity associated with native plants is still very scarce. In this study, a total of 257 endophytic Actinobacterial isolates were obtained using Actinobacteria-selective media from surface sterilized roots, stems, leaves and seeds of the oil-seed plant Jatropha curcas L. collected from dry-hot valley soil. Morphological and the 16S rRNA sequence analysis showed that most of the isolates belong to the Streptomyces genus and other non-Streptomyces strains distributed onto 13 genera, with several new species. 19 strains were found to have ACC deaminase activity and they belong to the genera Streptomyces, Nonomuraea, Micrococcus and Kibdelosporangium. The functional ability of the ACC deaminase producing isolates to produce indole-3-acetic acid (IAA), siderophores, mineral phosphate solubilization and growth on nitrogen free semi-solid medium was also determined. Seven strains were selected to inoculate the axenically grown seedlings and they resulted in a significant increase in the seedling fresh weight, the seedling length, the root length and the leaf area of the endophytes-treated seedlings compared to the control. This is the first report on the diversity and characterization of endophytic Actinobacteria associated with important oil-seed plant J. curcas L. Our results demonstrate that some endophytic Actinobacterial strains have the promising PGP attributes to be developed as biofertilizers to enhance soil fertility and promote the plant growth.

  • abundant and diverse endophytic Actinobacteria associated with medicinal plant maytenus austroyunnanensis in xishuangbanna tropical rainforest revealed by culture dependent and culture independent methods
    Environmental Microbiology Reports, 2012
    Co-Authors: Huahong Chen, Wen-jun Li, Jihong Jiang, Guozhen Zhao, Jie Li, Lihua Xu


    Endophytes are now considered as an important component of biodiversity. However, the diversity of endophytic Actinobacteria associated with tropical rainforest native medicinal plants is essentially unknown. In this study, the diversity of endophytic Actinobacteria residing in root, stem and leaf tissues of medicinal plant Maytenus austroyunnanensis collected from tropical rainforest in Xishuangbanna, China was investigated with a combination of cultivation and culture-independent analysis on the basis of 16S rRNA gene sequencing. By using different selective isolation media and methods, a total of 312 Actinobacteria were obtained, and they were affiliated with the order Actinomycetales (distributed into 21 genera). Based on a protocol for endophytes enrichment, three 16S rRNA gene clone libraries were constructed and 84 distinct operational taxonomic units were identified and they distributed among the orders Actinomycetales and Acidimicrobiales, including eight suborders and at least 38 genera with a number of rare Actinobacteria genera. Phylogenetic analysis showed that 32% of the clones in the libraries had lower than 97% similarities with related type strains. Interestingly, six genera from the order Actinomycetales and uncultured clones from Acidimicrobiales have not, to our knowledge, been previously reported as endophytes. Our study confirms abundant endophytic Actinobacterial consortium in tropical rainforest native plant and suggests that this special habitat represents an underexplored reservoir of diverse and novel Actinobacteria of potential interest for bioactive compounds discovery.

Radhey S Gupta – 2nd expert on this subject based on the ideXlab platform

  • phylogenetic framework and molecular signatures for the main clades of the phylum Actinobacteria
    Microbiology and Molecular Biology Reviews, 2012
    Co-Authors: Radhey S Gupta


    Summary: The phylum Actinobacteria harbors many important human pathogens and also provides one of the richest sources of natural products, including numerous antibiotics and other compounds of biotechnological interest. Thus, a reliable phylogeny of this large phylum and the means to accurately identify its different constituent groups are of much interest. Detailed phylogenetic and comparative analyses of >150 Actinobacterial genomes reported here form the basis for achieving these objectives. In phylogenetic trees based upon 35 conserved proteins, most of the main groups of Actinobacteria as well as a number of their superageneric clades are resolved. We also describe large numbers of molecular markers consisting of conserved signature indels in protein sequences and whole proteins that are specific for either all Actinobacteria or their different clades (viz., orders, families, genera, and subgenera) at various taxonomic levels. These signatures independently support the existence of different phylogenetic clades, and based upon them, it is now possible to delimit the phylum Actinobacteria (excluding Coriobacteriia) and most of its major groups in clear molecular terms. The species distribution patterns of these markers also provide important information regarding the interrelationships among different main orders of Actinobacteria. The identified molecular markers, in addition to enabling the development of a stable and reliable phylogenetic framework for this phylum, also provide novel and powerful means for the identification of different groups of Actinobacteria in diverse environments. Genetic and biochemical studies on these Actinobacteria-specific markers should lead to the discovery of novel biochemical and/or other properties that are unique to different groups of Actinobacteria.

  • signature proteins that are distinctive characteristics of Actinobacteria and their subgroups
    Antonie Van Leeuwenhoek International Journal of General and Molecular Microbiology, 2006
    Co-Authors: Ragi Paramanathan, Radhey S Gupta


    The Actinobacteria constitute one of the main phyla of Bacteria. Presently, no morphological and very few molecular characteristics are known which can distinguish species of this highly diverse group. In this work, we have analyzed the genomes of four Actinobacteria (viz. Mycobacterium leprae TN, Leifsonia xyli subsp. xyli str. CTCB07, Bifidobacterium longum NCC2705 and Thermobifida fusca YX) to search for proteins that are unique to Actinobacteria. Our analyses have identified 233 Actinobacteria-specific proteins, homologues of which are generally not present in any other bacteria. These proteins can be grouped as follows: (i) 29 proteins uniquely present in most sequenced Actinobacterial genomes; (ii) 6 proteins present in almost all Actinobacteria except Bifidobacterium longum and another 37 proteins absent in B. longum and few other species; (iii) 11 proteins which are mainly present in Corynebacterium, Mycobacterium and Nocardia (CMN) subgroup as well as Streptomyces, T. fusca and Frankia sp., but they are not found in Bifidobacterium and Micrococcineae; (iv) 8 proteins that are specific for T. fusca and Streptomyces species, plus 2 proteins also present in the Frankia species; (v) 13 proteins that are specific for the Corynebacterineae or the CMN group; (vi) 14 proteins only found in Mycobacterium and Nocardia; (vii) 24 proteins unique to different Mycobacterium species; (viii) 8 proteins specific to the Micrococcineae; (ix) 85 proteins which are distributed sporadically in Actinobacterial species. Additionally, many examples of lateral gene transfer from Actinobacteria to Magnetospirillum magnetotacticum have also been identified. The identified proteins provide novel molecular means for defining and circumscribing the Actinobacteria phylum and a number of subgroups within it. The distribution of these proteins also provides useful information regarding interrelationships among the Actinobacterial subgroups. Most of these proteins are of unknown function and studies aimed at understanding their cellular functions should reveal common biochemical and physiological characteristics unique to either all Actinobacteria or particular subgroups of them. The identified proteins also provide potential targets for development of drugs that are specific for Actinobacteria.

  • conserved indels in protein sequences that are characteristic of the phylum Actinobacteria
    International Journal of Systematic and Evolutionary Microbiology, 2005
    Co-Authors: Radhey S Gupta


    Gram-positive bacteria with a high G+C content are currently recognized as a distinct phylum, Actinobacteria, on the basis of their branching in 16S rRNA trees. Except for an insert in the 23S rRNA, there are no unique biochemical or molecular characteristics known at present that can distinguish this group from all other bacteria. In this work, three conserved indels (i.e. inserts or deletions) are described in three widely distributed proteins that are distinctive characteristics of the Actinobacteria and are not found in any other groups of bacteria. The identified signatures are a 2 aa deletion in cytochrome-c oxidase subunit 1 (Cox1), a 4 aa insert in CTP synthetase and a 5 aa insert in glutamyl-tRNA synthetase (GluRS). Additionally, the Actinobacterial specificity of the large insert in the 23S rRNA was also tested. Using primers designed for conserved regions flanking these signatures, fragments of most of these genes were amplified from 23 Actinobacterial species, covering many different families and orders, for which no sequence information was previously available. All the 61 sequenced fragments, except two in GluRS, were found to contain the indicated signatures. The presence of these signatures in various species from 20 families within this phylum provides evidence that they are likely distinctive characteristics of the entire phylum, which were introduced in a common ancestor of this group. The absence of all four of these signatures in Symbiobacterium thermophilum suggests that this species, which is distantly related to other Actinobacteria in 16S rRNA and CTP synthetase trees, may not be a part of the phylum Actinobacteria. The identified signatures provide novel molecular means for defining and circumscribing the phylum Actinobacteria. Functional studies on them should prove helpful in understanding novel biochemical and physiological characteristics of this group of bacteria.

Christopher M. M. Franco – 3rd expert on this subject based on the ideXlab platform

  • Biogeography and emerging significance of Actinobacteria in Australia and Northern Antarctica soils
    Soil Biology & Biochemistry, 2020
    Co-Authors: Ricardo Araujo, Vadakattu V. S. R. Gupta, Frank Reith, Andrew Bissett, Pauline M. Mele, Christopher M. M. Franco


    Abstract Actinobacteria play key roles in terrestrial ecosystem functioning. They contribute to global carbon cycling through the decomposition of soil organic matter, they increase plant productivity and are widely known as prolific producers of bioactive compounds essential for human and animal health. The almost century-old search for new members of the Actinobacteria has so far proceeded without a compass directing researchers towards regions of Actinobacterial abundance and novel diversity. We show that such regions are found in Australia, a dry and warm continent with highly weathered soils. Here, Actinobacteria are highly abundant suggesting they may play an increasingly important role as climate becomes warmer and drier. Australian continental Actinobacterial diversity is associated with physicochemical factors, especially soil pHwater, exchangeable calcium and the regional climate. Patterns of their biogeography suggest that only a small fraction of Actinobacteria have the capability of dispersing throughout the Southern Hemisphere, especially across oceans. We identified a core soil Actinobacterial community across mainland Australia of 2211 OTUs which reduced to 490 OTUs when Tasmania, King Island, Christmas Island and Northern Antarctica were included. These 490 OTUs mapped to three families, i.e., Gaiellaceae, Micromonosporaceae and Nocardiaceae. This study also implicates disturbance regimes associated with agriculture in the reduction of Actinobacterial diversity, highlighting undisturbed soils as reservoirs for enriching adjacent agricultural soils. Interestingly, high OTU similarities between King Island and areas in Antarctica suggest a shared evolutionary history that persists to this day. In conclusion, Actinobacteria are highly abundant in Australian soils, suggesting they could play increasingly important roles in soils globally under future climate scenarios.

  • Symbiosis and Pathogenicity of Actinobacteria
    Biology and Biotechnology of Actinobacteria, 2017
    Co-Authors: Yitayal S. Anteneh, Christopher M. M. Franco


    Actinobacteia are known to interact with a number of macro and microorganisms. Symbiotic interaction between Actinobacteria and its host observed in insects, human, animals and plants, where the bacteria provide protection of the host against pathogen, produce essential nutrients, enzymes and facilitate digestion of food particles. In the other hand, Actinobacteria also responsible in causing of diseases like actinomycetoma and tuberculosis in human, nocardiosis and dermatophilosis in animals, and scab in plants. This chapter covers the literature which describes the symbiotic interaction of Actinobacteria with different vertebrates and invertebrates, as well as common Actinobacteria associated diseases in human, animals and plants.

  • Endophytic Actinobacteria: Beneficial Partners for Sustainable Agriculture
    Endophytes: Biology and Biotechnology, 2017
    Co-Authors: Ricardo Araujo, Onuma Kaewkla, Christopher M. M. Franco


    Endophytic Actinobacteria have been proven to be effective partners that have beneficial functions with a number of crop plants. A large number of studies have been carried out, showing these positive effects in laboratories and glasshouses, but with fewer reports of their effectiveness in the field. This chapter highlights the results of field trials of Actinobacterial endophytes conducted with cereals, vegetables such as tomato, cucumber, or cabbage, legumes such as chickpea or pea, fruits such as melon or grapes, peanuts, and woody plants.