| Halophilic archaea is a kind of microorganisms that widely distributed in the hypersaline habitat.Under this special environmental conditions,the archaea especially which living in extremely high-salt areas must have some special physiological characteristics and adaptive mechanisms.The study of halophilic archaea is of great significance in promoting the progress of taxonomy,revealing the basic rules of life movement and the origin of species as well as the interaction between microorganisms and the ecological environment.Due to its special status in biological evolution system and potential value in industrial application,Halophilic archaea has become a valuable resource for the study of microbial resources,classification and exploration of microbial physiological mechanisms.In the process of studying the resource of halophilic actinomycetes in aerial hyphae and spore production,our laboratory accidentally isolated a halophilic archaea YIM 93972 from the sediment sample of qijiajing salt lake in xinjiang.The optimum salt concentration required for the growth of this halophilic archaea was 25%NaCl(w/v),which was identified as an extreme halophilic archaea.Different from other archaea,this strain presents streptomyces-like colony and has the ability to produce mycelia and spores.It is the first archaea with morphological development and differentiation that can be reproduced by spores.It is very special and has important scientific research value.The polyphasic taxonomic method was used to confirm its taxonomic status as a candidate new genus of halophilic archaea.The complete genome map of YIM 93972 was obtained by whole genome sequencing,with the genome size of 3748058bp.The genome-wide map consists of two chromosomes and three plasmids.Comparison of the COG database showed that the bacterial strain encoded a total of 3744 protein genes,which were involved in 137 metabolic signaling pathways through KEGG database analysis.Due to the particularity of YIM 93972 morphology,this experiment studied the culture characteristics of the strain from multiple perspectives.1.Colony morphology.The experimental results showed that YIM 93972 could grow in ISP 2,ISP 3.ISP 4,JCM 168.and NA medium,and that in ISP 4 medium,the aerial hyphae was developed.The characteristics of different salt concentrations and incubation time in ISP 4 medium were as follows:in ISP 4 medium,the optimal salt concentration for the growth of aerial hyphae was between 20%and 25%NaC1(w/v).2.Microscopic morphology.The results of scanning electron microscopy(sem)on the liquid culture characteristics of ISP 4 medium showed that the mycelium was filaments and the mycelium was very strong,and spore was formed at the end of the mycelium.The same morphological characteristics were observed under the condition of solid culture of ISP 4 mediun.After ultrathin sections were processed.the results of transmission electron microscopy showed that the cross section was round or oval.and the spore diameter was about 300-400nm.Experiments showed that under different culture conditions,the strain had stable morphological characteristics and could produce hyphae and spores.In order to reveal the morphological development mechanism of the strain from the perspective of microbiology,NTG mutagenesis and single factor culture were also conducted in this experiment.Two morphological transitional strains and three morphological mutant strains were obtained by NTG mutagenesis and four successive passages.The resistance experiment of Bialaphos was carried out and the mycelial development mechanism was preliminarily verified.Univariate experiments were conducted with ISP 4 medium and JCM 168 medium,and it was found that Mg2+ and nitrogen source types had significant effects on the growth of YIM 93972 aerial hyphae.These preliminary studies provided research materials and experimental data for the future revelation of the morphological and developmental mechanism of the strain. |
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