RECENT ADVANCES IN CULTURING THE UNCULTURABLE BACTERIA

ABSTRACT The diversity of micro-organisms like bacteria is poorly studied and categorized. Preserving them like plants and animals is extremely difficult as these tiny organisms cannot be observed with the naked eye. Moreover these organisms cannot be classified solely based on their phenotypic characters therefore various methods are being employed to access the diversity of these unculturables. The attempts are being made to understand the biology of the unculturable bacteria by using tools of metagenomics, creating artificial environment in the laboratory, co-culturing in combinations with microfludics devices etc. While metagenomic study provides culture independent access to whole microbial communities based on their genetic material recovered directly from an environment, it is highly difficult to get information about physiology of an organism. The present review discusses the reasons for un-cultivability of these organisms and advances in molecular ecology to culture the same

Mycorrhiza: Fungus and Plant Root Symbiosis in the Functioning of Natural Ecosystems

ABSTRACT Mycorrhiza are global associations including diverse morphological, functional and evolutionary categories. Almost all the plant species of natural vegetation and the agricultural crop plants of the tropics live in mycorrhizal association with fungi. Vesicular arbuscular mycorrhizal associations (VAM), which are also called arbuscular mycorrhiza (AM) or glomeromycotan mycorrhiza (GM), are the most widespread and common root-fungus associations. Mycorrhizal fungi are better than roots at acquiring poorly mobile phosphate from the soil, which they exchange with their host plant for their sole source of carbon. In addition to their role in phosphate acquisition, AMF have other potential benefits to plants like the uptake of important nutrients such nitrogen, protection against root pathogens, water acquisition and the mediation of pollution effects. Current review discusses the biology of mycorrhiza in relation to mutulistic relationship with plants in natural eco-system

Adaptive laboratory evolution triggers pathogen-dependent broad-spectrum antimicrobial potency in Streptomyces

Abstract Background In the present study, adaptive laboratory evolution was used to stimulate antibiotic production in a Streptomyces strain JB140 (wild-type) exhibiting very little antimicrobial activity against bacterial pathogens. The seven different competition experiments utilized three serial passages (3 cycles of adaptation-selection of 15 days each) in which Streptomyces strain (wild-type) was challenged repeatedly to one (bi-culture) or two (tri-culture) or three (quadri-culture) target pathogens. The study demonstrates a simple laboratory model to study the adaptive potential of evolved phenotypes and genotypes in Streptomyces to induce antibiotic production. Results Competition experiments resulted in the evolution of the wild-type Streptomyces strain JB140 into the seven unique mutant phenotypes that acquired the ability to constitutively exhibit increased antimicrobial activity against three bacterial pathogens Salmonella Typhi (NCIM 2051), Staphylococcus aureus (NCIM 2079), and Proteus vulgaris (NCIM 2027). The mutant phenotypes not only effectively inhibited the growth of the tested pathogens but were also observed to exhibit improved antimicrobial responses against one clinical multidrug-resistant (MDR) uropathogenic Escherichia coli (UPEC 1021) isolate. In contrast to the adaptively evolved mutants, only a weak antimicrobial activity was detected in the wild-type parental strain. To get molecular evidence of evolution, RAPD profiles of the wild-type Streptomyces and its evolved mutants were compared which revealed significant polymorphism among them. Conclusion The competition-based adaptive laboratory evolution method can constitute a platform for evolutionary engineering to select improved phenotypes (mutants) with increased antibacterial profiles against targeted pathogens

Draft Genome Sequence of Streptomyces sp. Strain DH-12, a Soilborne Isolate from the Thar Desert with Broad-Spectrum Antibacterial Activity

Jiao J, Paterson J, Busche T, et al. Draft Genome Sequence of Streptomyces sp. Strain DH-12, a Soilborne Isolate from the Thar Desert with Broad-Spectrum Antibacterial Activity. MICROBIOLOGY RESOURCE ANNOUNCEMENTS. 2018;6(9): UNSP e00108-18.Strain DH-12 exhibits broad-spectrum antibacterial activity toward Gram-positive and Gram-negative pathogens. The 7.6-Mb draft genome sequence gives insight into the complete secondary metabolite production capacity and reveals genes putatively responsible for its antibacterial activity, as well as genes which enable the survival of the organism in an extreme arid environment