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. 2017 Mar 31;32(1):24-31.
doi: 10.1264/jsme2.ME16095. Epub 2017 Mar 4.

Streptomyces cameroonensis sp. nov., a Geldanamycin Producer That Promotes Theobroma cacao Growth

Thaddée Boudjeko  1 , Romaric Armel Mouafo Tchinda, Mina Zitouni, Joëlle Aimée Vera Tchatchou Nana, Sylvain Lerat, Carole Beaulieu
Affiliations

Streptomyces cameroonensis sp. nov., a Geldanamycin Producer That Promotes Theobroma cacao Growth

Thaddée Boudjeko et al. Microbes Environ. .

Abstract

The taxonomy of an actinobacterial strain, designated JJY4T, was established using a polyphasic approach. JJY4T was isolated from the rhizosphere of Chromolaena odorata in Yaoundé (Cameroon) during a project for the selection of biological control agents. Strain JJY4T exhibited antimicrobial activities against bacteria, fungi, and oomycetes. Strain JJY4T also exhibited the traits of plant growth-promoting rhizobacteria such as the solubilization of inorganic phosphate, production of siderophores and indole-3-acetic acid, and 1-aminocyclopropane-1-carboxylate deaminase activity. In planta assays performed on cocoa plantlets confirmed that strain JJY4T exhibited strong abilities to promote plant growth and protect against Phytophthora megakarya, the main causal agent of cocoa pod rot. The formation of rugose-ornamented spores in spiral spore chains by strain JJY4T is a typical feature of members found in the Streptomyces violaceusniger clade and, similar to some members of the clade, strain JJY4T produces geldanamycin. A phylogenetic analysis based on 16S rRNA gene sequences confirmed this classification and suggests that strain JJY4T be added to the subclade constituted of the type strains Streptomyces malaysiensis DSM 41697T and Streptomyces samsunensis DSM 42010T. However, DNA-DNA relatedness and physiological characteristics allowed for the differentiation of strain JJY4T from its closest phylogenetic relatives. Based on these results, strain JJY4T (=NRRL B-65369, =NBRC 112705) appears to represent a novel species in the S. violaceusniger clade for which the proposed name is Streptomyces cameroonensis sp. nov.

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Figures

Fig. 1
Fig. 1
Root and aerial biomasses of 3-month-old cocoa plantlets grown in different substrates: non-inoculated, inoculated with strain JJY4T, inoculated with Phytophthora megakarya, or co-inoculated with strain JJY4T and P. megakarya. Values with different letters are significantly different (LSD test, root biomass: lower case, aerial biomass: upper case).
Fig. 2
Fig. 2
Scanning electron micrograph showing the formation of spiral chains of rugose-ornamented spores by strain JJY4T grown on yeast extract-malt extract (ISP-2 medium) agar at 30°C for 14 d. Bars represent 5 μm.
Fig. 3
Fig. 3
Maximum likelihood phylogenetic tree, based on nearly complete 16S rRNA gene sequences (1473 nt) showing the position of strain JJY4T on the Streptomyces violaceusniger gene tree. The bar represents a distance of 0.01 substitutions per nucleotide.
See this image and copyright information in PMC

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