Gordonia sp. are members of the actinomycete family, their contribution to the environment improvement and environmental protection by their biological degradation ability, but there are few studies on the antimicrobial activity of their secondary metabolites. Our team isolated and purified an actinomycete WA 4-31 from the intestinal tract of Periplaneta americana, firstly identified the strain WA 4-31 by the morphological characteristics and the phylogenetic analyses, and found it was completely homologous to the strain of Gordonia terrae from the Indian desert. Meanwhile, actinomycin D (1), actinomycin X2 (2), mojavensin A (3) and cyclic (leucine-leucne) dipeptide (4) were obtained from the EtOAc extract from the broth of WA 4-31. Compounds 1–4 showed anti-fungus activities against Candida albicans, Aspergillus niger, A. fumigatus and Trichophyton rubrum, also anti-MRSA and inhibited Escherichia coli in different degree. Interestingly, we found when 3 was mixed with 4 with ratio of 1:1, the activity of the mixture on anti-Candida albicans was better than the single. Besides, compounds 1–3 had varying degrees of antiproliferative activities on CNE-2 and HepG-2 cell lines. These indicated that Gordonia rare actinomycete from the intestinal tract of Periplaneta americana possessed a potential as a source of active secondary metabolites.

Microbial secondary metabolites are one of the main sources of bioactive natural products. It is estimated that around 75% of all antibiotics are derived from secondary metabolites produced by filamentous actinomycete. Gordonia sp. are members of the actinomycete family, their contribution to the environment improvement and environmental protection by their biological degradation ability, but there are few studies on the antimicrobial activity of their secondary metabolites. Our team isolated a Gordonia strain WA 4–31 with anti-Candida albicans activity from the intestinal tract of Periplaneta americana in the early stage. In this study, we firstly identified the strain WA 4–31 by the morphological characteristics and the phylogenetic analyses, and found that it homologous to a strain of Gordonia from the Indian desert by 100%. Then four compounds, Actinomycin D (1), Actinomycin X2 (2), Mojavensin A (3) and cyclic (leucine-leucne) dipeptide (4) were purified from the ethyl acetate extract of the fermented broth of the strain. The compounds 1–4 had activities against Candida albicans, Aspergillus niger, Aspergillus fumigatus and Trichophyton rubrum. They also had activities against methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli.coli in different degree. Interestingly, we found that when Mojavensin A was mixed with compound 4 ratio of 1:1, the activity of the mixture on anti-Candida albicans was better than the single. Besides, compounds 1–3 had varying degrees of antiproliferative activity on CNE-2 cells and HepG-2 cells. These indicated that Gordonia rare actinomycete from the intestinal tract of Periplaneta americana possessed a potential as a source of active secondary metabolites.

Background: As we all know, bacterial and fungal infections have become one of the threats to human health. Microbial secondary metabolites are one of the main sources of bioactive natural products. It is estimated that around 60% of all foregone antibiotics are derived from secondary metabolites produced by filamentous actinomycete bacteria. Gordonia spp. are members of the actinomycete family, their contribution to the environment improvement and environmental protection by their biological degradation ability, but there are few studies on their antimicrobial activity of their secondary metabolites. Our team isolated a Gordonia strain WA 4-31 with anti-Candida albicans activity from the intestinal tract of Periplaneta americana in the early stage.Results: In this study, we firstly identified the strain WA 4-31 by the morphological characteristics and the phylogenetic analyses, and found that it homologous to a strain of Gordonia from the Indian desert (EU333873) by 100%. Then four compounds, Actinomycin D (1), Actinomycin X2 (2), Mojavensin A (3) and cyclic (leucine-leucne) dipeptide (4) were purified from the EtOH extract of the fermented broth of the strain. The compounds 1-4 had activities against Candida albicans, Aspergillus niger, Aspergillus fumigatus and Trichophyton rubrum. They also had activities against MRSA, S.aureus, K.peneumoniae and E.coli in different degree. The minimum inhibitory concentration of Actinomycin D and Actinomycin X2 on MASA was 0.25 μg/mL. Interestingly, we found that when Mojavensin A was mixed with compound 4 ratio of 1:1, the solution of the compounds was better than the single on anti-Candida albicans. Besides, compounds 1-3 had varying degrees of cytotoxicity on CNE-2 cells and HepG-2 cells.Conclusions: The present study firstly reported the antimicrobial compounds isolated from Gordonia. These indicated that rare actinomycetes from the intestinal tract of Periplaneta americana possessed a potential as a source of active secondary metabolites.

Background Klebsiella pneumoniae is one of the main pathogens of clinical isolation and nosocomial infections, as K. pneumoniae show broad-spectrum resistance to β-lactam and carbapenem antibiotics. It is emerging clinical need for a safe and effective drug to anti-K. pneumoniae. At present, Achromobacter mainly focused on its degradation of petroleum hydrocarbons, polycyclic aromatic hydrocarbons, assisting insects to decompose, degrade heavy metals and utilize organic matter, but there were few reports on the antibacterial activity of the secondary metabolites of Achromobacter. Results In this study, a strain WA5-4-31 from the intestinal tract of Periplaneta americana exhibited strong activity against K. Pneumoniae through preliminary screening. The strain was determined to be Achromobacter sp. through the morphological characteristics, genotyping and phylogenetic tree analysis, which is homologous to Achromobacter ruhlandii by 99%, its accession numbe in GenBank at National Center for Biotechnology Information (NCBI) is MN007235, and its deposit number was GDMCC NO.1.2520. Six compounds (Actinomycin D, Actinomycin X2, Collismycin A, Citrinin, Neoechinulin A and Cytochalasin E) were isolated and determined by activity tracking, chemical separation, nuclear magnetic resonance (NMR) and mass spectrometry (MS) analysis. Among them, Actinomycin D, Actinomycin X2, Collismycin A, Citrinin and Cytochalasin E showed a good effect on anti-K. pneumoniae, with MIC values of 16–64 µg/mL. Conclusions The study reported Achromobacter, which was from the intestinal tract of Periplaneta americana with the activity against K. Pneumoniae, can produce antibacterial compounds for the first time. It lays the foundation for development of secondary metabolites of insect intestinal microorganisms.