<i>Streptomyces cameroonensis</i> sp. nov., a Geldanamycin Producer That Promotes <i>Theobroma cacao</i> Growth

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.

Commercial Biocontrol Agents Reveal Contrasting Comportments Against Two Mycotoxigenic Fungi in Cereals: Fusarium Graminearum and Fusarium Verticillioides

“…To identify the culture media best suited to the dual culture bioassay of each of the BCAs/pathogen, seven culture media candidates were chosen: PDA, Czapeck agar (CZA), Czapeck yeast agar (CYA), and oat meal agar (OMA) for their affinity with pathogens [45][46][47][48], and potato dextrose agar (PDA), International Streptomyces Project Medium 2 (ISP2), malt yeast agar (MYA), and corn meal agar (CMA) for their affinity with BCAs (respectively all BCAs, Myco [49,50], Xeda [13,51,52], and Poly [53][54][55]). The compositions of media are available in Figure A1.…”

Biocatalytic potential of Streptomyces spp. isolates from rhizosphere of plants and mycorrhizosphere of fungi

“…Streptomyces originating from the rhizosphere of plants or mycorrhizosphere of fungi have previously been explored for the production of bioactive molecules , however they have not been exploited for biocatalysis. Considering potential uses of hydrolases, phenol oxidases and peroxidases, as well as aminotransferases, we functionally screened 118 Streptomyces isolates from rhizosphere of plants or mycorrhizosphere of fungi for 10 different enzymes (hydrolase [cellulase EC 3.2.1.4, cutinase EC 3.1.1.74, gelatinase EC 3.4.24.35, lipase EC 3.1.1.3, protease EC 3.4.21, PHA depolymerase EC 3.1.1.75], phenol oxidase and peroxidase [laccase EC 1.10.3.2, tyrosinase EC 1.14.18.1, and lignin peroxidase EC 1.11.1.14], and aminotransferase EC 2.6.1).…”

“…Streptomyces originating from the rhizosphere of plants or mycorrhizosphere of fungi have previously been explored for the production of bioactive molecules [18][19][20], however they have not been exploited for biocatalysis. Considering potential uses of hydrolases, phenol oxidases and peroxidases, as well as aminotransferases, we functionally screened 118 Streptomyces isolates from rhizosphere of plants or mycorrhizosphere of fungi for 10…”

Streptomyces lydicus A01 affects soil microbial diversity, improving growth and resilience in tomato

“…Streptomyces cameroonensis , a producer of geldanamycin, promotes Theobroma cacao growth (Boudjeko et al ). Studies indicate that Streptomyces isolate C can be used as a biofertilizer in saline soils, increasing the germination rate, percentage, and uniformity, and shoot length and dry weight, when compared to the control.…”