Three Types of Antibiotics Produced from Rhodococcus erythropolis Strains

Abstract

A total of 15 Rhodococcus erythropolis strains were characterized as antibiotic producers and classified into three groups according to their antibiotic spectrum and growth compatibility (strains within a group did not inhibit each other's growth). Each of the antibiotic groups exhibited antibiotic activity against a taxonomically different breadth of bacteria: Group I exhibited antibiotic activity against a broad range of Gram-positives; Group II, mainly against the genus Rhodococcus and some other Gram-positives; and Group III, particularly against R. erythropolis. The antibiotic compounds of the strains belonging to Groups I and II were partially purified from liquid culture media. It was found that each group produces distinct antibiotics. In contrast to the diversity of antibiotic activity, the sequence of the 16S rRNA gene in the analyzed 1,440-nt region was found to be identical in all these 15 Rhodococcus strains. In addition to the antibiotic diversity in R. erythropolis strains, we elucidated the diversity in antibiotic-producing species of the genus Rhodococcus. Thus far, only a few antibiotic-producing strains have been reported in Rhodococcus; however, our results demonstrated that the genus comprises diverse antibiotic producers, and is a good source of new antibiotics.Key words: Actinobacteria, antibiotic, diversity, RhodococcusIn actinomycetes, numerous antibiotic producers have been identified. The genus Streptomyces, in particular, is well known for its remarkable antibiotic-producing ability. Many Streptomyces species produce various antibiotics. Other genera in the phylum Actinobacteria, such as Actinomadura 2) , Arthrobacter 8) , and Nocardia 23) have also been reported to produce antibiotics, though they have not been studied extensively. In the last few decades, the genus Rhodococcus, a member of Actinobacteria, has received considerable attention for its remarkable ability to degrade persistent chemicals such as polychlorinated biphenyls (PCBs) 14,15) and nitrophenols 4,11) ; the industrial application of nitrile hydratase that is synthesized by the members of this genus 13) has also been investigated. Previous research has also focused on the plant and mammalian pathogenic characteristics of some species belonging to this genus 3,16) . Extensive research and considerable progress have been reported in these fields. However, the antibiotic-producing ability of rhodococci has not yet been studied extensively. To date, only a few antibiotic-producing Rhodococcus strains and the antibiotics that they produce have been reported 1,6) . The rhodopeptin isolated from Rhodococcus sp. Mer-N1033 is a cyclic peptide that exhibits antibiotic activity against several fungal species, such as Candida albicans and Crytococcus neoformans, but not against bacteria 1) . Another antibiotic compound lariatin isolated from Rhodococcus sp. K01-B0171 is also a cyclic peptide that exhibits antibiotic activity, particularly against mycobacterial species 6) . In addition to the two strains mentioned above, the ge...

A Quinoline Antibiotic from Rhodococcus erythropolis JCM 6824

“…The sample was subjected to reversed-phase HPLC [column: TSKgel ODS-80Ts, 4.6 mm I.D.ϫ15 cm (TOSOH, Tokyo, Japan); mobile phase: 65ϳ75% MeOH (0ϳ8 minutes) and 90% MeOH (8ϳ12 minutes); flow rate: 1.0 ml/minute; monitor wavelength: 220ϳ600 nm] [1]. A single peak that retained antibiotic activity and eluted at a retention time of 10.6 minutes, was reproducibly collected.…”

“…Recently, we have reported the genus Rhodococcus is also a prolific antibiotic producer [1]. At least, five species and 18 strains of Rhodococcus have been demonstrated to exhibit anti-microbial activity.…”

“…At least, five species and 18 strains of Rhodococcus have been demonstrated to exhibit anti-microbial activity. R. erythropolis, in particular, includes three groups of strains that produce respective antibiotics [1]. One of the antibiotic-producing strains, R. erythropolis JCM 6824, and also the partially purified antibiotic isolated from this strain, exhibits strong antibiotic against a broad range of Gram-positive bacteria.…”

Rhodococcus pedocola sp. nov. and Rhodococcus humicola sp. nov., two antibiotic-producing actinomycetes isolated from soil

“…Species of this genus are also potential sources for novel biosurfactants (De Carvalho & da Fonseca, 2005;Peng et al, 2008;White et al, 2013). Besides, the genus Rhodococcus is a member of the phylum Actinobacteria, and some species of Rhodococcus can produce antibiotics (Kitagawa & Tamura, 2008;Nachtigall et al, 2010). At the time of writing, 56 species of the genus Rhodococcus with validly published names have been described (http://www.bacterio.net/rhodococcus.html; January 2016).…”

New Vector System for Random, Single-Step Integration of Multiple Copies of DNA into the Rhodococcus Genome

“…Many species of actinobacteria are well known as attractive hosts for the production of biologically active compounds since they can easily utilize cheap complex industrial media and possess excellent secretion capacities. This group includes several antibiotic producers (12,15) and manufacturers of enzymes (5), amino acids (11), and heterologous proteins (3); hence, they are of high industrial, pharmacological, and commercial interest. Among the genera in this group are Corynebacterium, Mycobacterium, Streptomyces, Nocardia, and Rhodococcus.…”