Cyclodipeptide (CDP) composed of two amino acids is the simplest cyclic peptide. These two amino acids form a typical diketopiperazine (DKP) ring by linking each other with peptide bonds. This characteristic stable ring skeleton is the foundation of CDP to display extensive and excellent bioactivities, which is beneficial for CDPs' pharmaceutical research and development. The natural CDP products are well isolated from actinomycetes. These bacteria can synthesize DKP backbones with nonribosomal peptide synthetase (NRPS) or cyclodipeptide synthase (CDPS). Moreover, actinomycetes could produce a variety of CDPs through different enzymatic modification. The presence of these abundant and diversified catalysis indicates that actinomycetes are promising microbial resource for exploring CDPs. This review summarized the pathways for DKP backbones biosynthesis and their post-modification mechanism in actinomycetes. The aim of this review was to accelerate the genome mining of CDPs and their isolation, purification and structure identification, and to facilitate revealing the biosynthesis mechanism of novel CDPs as well as their synthetic biology design.
Actinobacteria/metabolism* ; Actinomyces/metabolism* ; Biological Products/metabolism* ; Bacteria/metabolism* ; Diketopiperazines/metabolism* ; Amino Acids

Ribosomal engineering is a technique that can improve the biosynthesis of secondary metabolites in the antibiotics-resistant mutants by attacking the bacterial RNA polymerase or ribosome units using the corresponding antibiotics. Ribosomal engineering can be used to discover and increase the production of valuable bioactive secondary metabolites from almost all actinomycetes strains regardless of their genetic accessibility. As a consequence, ribosomal engineering has been widely applied to genome mining and production optimization of secondary metabolites in actinomycetes. To date, more than a dozen of new molecules were discovered and production of approximately 30 secondary metabolites were enhanced using actinomycetes mutant strains generated by ribosomal engineering. This review summarized the mechanism, development, and protocol of ribosomal engineering, highlighting the application of ribosomal engineering in actinomycetes, with the aim to facilitate future development of ribosomal engineering and discovery of actinomycetes secondary metabolites.
Actinobacteria/metabolism* ; Actinomyces/genetics* ; Anti-Bacterial Agents/metabolism* ; Multigene Family ; Ribosomes/genetics*

To investigate the effect of Polygonum multiflorum-Andrographis paniculata intercropping system on rhizosphere soil actinomycetes of P. multiflorum, the community structure and diversity of soil actinomycetes were studied by using the original soil as the control group and the rhizosphere soil actinomycetes communities of P. multiflorum under monoculture and intercropping systems as the experimental group. In this study 655 221 effective sequences were obtained with an average length of 408 bp. OTU coverage and rarefaction curve showed that the sequencing could represent the real situation of soil actinomycetes. According to the results of alpha diversity analysis, the diversity soil actinomycetes varied as follows: original soil>intercropping soil>monoculture soil. The soil actinomycetes community structure and the relative abundance of dominant genera were significantly changed by both monoculture and intercropping, especially monoculture. OTU clustering and PCA analysis of soil samples showed that all the soil samples were divided into three distinct groups and the original soil was more similar to intercropping soil. In addition, intercropping increased the relative abundance of some beneficial actinomyces, such as Kitasatospora and Mycobacterium, which was beneficial to maintain soil health and reduce the occurrence of soil-borne diseases. The results show that, P. multiflorum-A. paniculata intercropping reduced the change of community structure and the decrease of diversity of soil actinomycetes caused by P. multiflorum monoculture, and made the actinomycete community in rhizosphere soil of P. multiflorum close to the original soil.
Actinobacteria ; Actinomyces ; Agriculture ; Andrographis ; Fallopia multiflora ; Rhizosphere ; Soil ; Soil Microbiology

Brevibacterium spp. are gram-positive rods that are considered to be strictly nonpathogenic, and a very few cases of their infection in humans have been reported. In this study, we report a case of otitis caused by Brevibacterium otitidis. A 53-year-old woman, who visited the hospital, complained of symptoms, such as otorrhea from both ears, ear fullness, tinnitus, and hearing impairment, for several months. Ear discharge was cultured on blood agar for pathogen identification. Bacteria from the isolated colony were initially identified as Actinomyces odontolyticus by VITEK 2 (bioMerieux, France), whereas VITEK® MS (bioMerieux, France) identified them as Brevibacterium luteolum. Subsequently, bacteria from the isolated colony were confirmed as B. otitidis by 16S rRNA sequencing. Antimicrobial susceptibility testing confirmed their sensitivity to vancomycin and linezolid and resistance to clindamycin and penicillin. To our knowledge, this is the first reported case of otitis caused by B. otitidis in Korea.
Actinomyces ; Agar ; Bacteria ; Brevibacterium ; Clindamycin ; Ear ; Female ; Gram-Positive Rods ; Hearing Loss ; Humans ; Korea ; Linezolid ; Middle Aged ; Otitis ; Penicillins ; RNA, Ribosomal, 16S ; Tinnitus ; Vancomycin

Actinomyces species that were present in oral or nasal flora due to trauma or dental treatment. Actinomycosis shows a local calcified lesion associated with soft tissue density on computed tomography, which is similar to fungal sinusitis. Actinomycosis associated with fungal ball due to Aspergillus affecting sinus ventilation has been rarely reported. We experienced two cases of actinomycosis associated with fungal ball and successfully treated with endoscopic sinus surgery and oral antibiotics for 3 months without recurrence.]]>
Actinomyces ; Actinomycosis ; Anti-Bacterial Agents ; Aspergillosis ; Aspergillus ; Paranasal Sinuses ; Rare Diseases ; Recurrence ; Sinusitis ; Ventilation

Pelvic actinomycosis is an uncommon infectious disease. It induces a chronic, suppurative illness characterized by an infiltrative and granulomatous response and, thus, the clinical and radiologic findings may mimic other inflammatory and neoplastic conditions. A 56-year-old female with a long-standing intrauterine device was diagnosed with pelvic actinomycosis manifesting as a large uterine mass with locally infiltrative spread into surrounding tissue that mimicked uterine malignancy. Actinomyces israelii infection was confirmed with a surgical specimen, and the patient was treated with antibiotic medication. Pelvic actinomycosis must be included in the differential diagnoses of patients with an infiltrative pelvic mass extending across tissue planes or in patients with findings of multiple microabscesses, particularly in a patient with an intrauterine device, even the lesion primarily involves the uterus.
Actinomyces ; Actinomycosis ; Communicable Diseases ; Diagnosis, Differential ; Female ; Humans ; Intrauterine Devices ; Middle Aged ; Pelvic Inflammatory Disease ; Uterus

PURPOSE: To describe the effects and long-term outcomes of incision and curettage treatment in patients with lacrimal gland ductulitis.METHODS: Twenty-four patients (24 eyes) with lacrimal gland ductulitis who were treated at Saevit Eye Hospital from June 2010 to November 2016. All patients underwent incision and curettage through the lacrimal ductule, and granules or concretions were removed. After the procedure, oral and topical antibiotics, oral anti-inflammatory agent were used for a week. Clinical presentations of the patients were analyzed. The resolution of symptoms and inflammatory signs and recurrence were evaluated more than 12 months after the procedure including telephone follow-up by a specialist nurse.RESULTS: Common symptoms were a painful, swelling mass with mucous discharge (17 eyes) and conjunctival injection (7 eyes) at the lateral canthal area. During the procedure, 22 patients (91.7%) had typical sulfur granule of Actinomyces, and 10 patients (41.7%) had many cilia in the expressed debris from the ductule. Twenty-three of 24 patients had resolution of symptoms after the procedure and all but one patient (95.8%) showed no recurrence.CONCLUSIONS: Incision and curettage is a simple and less invasive procedure that may be considered as a first treatment option for lacrimal gland ductulitis. Furthermore, incision and curettage of the affected lacrimal ductule has been shown to be effective at minimizing long-term recurrence of lacrimal ductulitis.
Actinomyces ; Anti-Bacterial Agents ; Cilia ; Curettage ; Follow-Up Studies ; Humans ; Lacrimal Apparatus ; Recurrence ; Specialization ; Sulfur ; Telephone

BACKGROUND: Diverse microbiota exist in the lower respiratory tract. Although next generation sequencing (NGS) is the most widely used microbiome analysis technique, it is difficult to implement NGS in clinical microbiology laboratories. Therefore, we evaluated the performance of conventional culture methods together with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) in identifying microbiota in bronchoalveolar lavage (BAL) fluid. METHODS: BAL fluid samples (n=27) were obtained from patients undergoing diagnostic bronchoscopy for lung mass evaluation. Bacterial and fungal culture was performed with conventional media used in clinical microbiology laboratories. On an average, 20 isolated colonies were picked from each agar plate and identified by MALDI-TOF MS. Microbiome analysis using 16S rRNA NGS was conducted for comparison. RESULTS: Streptococcus spp. and Neisseria spp. were most frequently cultured from the BAL fluid samples. In two samples, Enterobacteriaceae grew predominantly on MacConkey agar. Actinomyces and Veillonella spp. were commonly identified anaerobes; gut bacteria, such as Lactobacillus, Bifidobacterium, and Clostridium, and fungi were also isolated. NGS revealed more diverse bacterial communities than culture, and Prevotella spp. were mainly identified solely by NGS. Some bacteria, such as Staphylococcus spp., Clostridium spp., and Bifidobacterium spp., were identified solely by culture, indicating that culture may be more sensitive for detecting certain bacteria. CONCLUSIONS: Culture and NGS of BAL fluid samples revealed common bacteria with some different microbial communities. Despite some limitations, culture combined with MALDI-TOF MS might play a complementary role in microbiome analysis using 16S rRNA NGS.
Actinomyces ; Agar ; Bacteria ; Bifidobacterium ; Bronchoalveolar Lavage Fluid* ; Bronchoalveolar Lavage* ; Bronchoscopy ; Clostridium ; Enterobacteriaceae ; Fungi ; Humans ; Lactobacillus ; Lung ; Mass Spectrometry ; Microbiota ; Neisseria ; Prevotella ; Respiratory System ; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization ; Staphylococcus ; Streptococcus ; Veillonella

Actinomyces are anaerobic, Gram-positive bacteria that are part of the endogenous flora of mucous membranes in humans. Infection caused by these bacteria is termed actinomycosis. The 3 most common types of actinomycosis are cervicofacial, abdominopelvic, and pulmonary. A previously healthy 6-year-old boy presented with the emergency room with fever, vomiting, and abdominal pain and initially diagnosed with acute appendicitis. Exploratory laparoscopy was done. Histologic finding demonstrated acute gangrenous appendicitis complicated by perforation and sulfur granules compatible with actinomycosis. Subsequently, he was diagnosed with abdominal actinomycosis and received long-term antibiotic therapy. Abdominal actinomycosis is uncommon in children and difficult to diagnose because of its nonspecific symptoms and of difficulties in growing Actinomyces in the clinical setting. It is necessary to include abdominal actinomycosis as a differential diagnosis of children presenting with abdominal pain.
Abdomen ; Abdominal Pain ; Actinomyces ; Actinomycosis ; Appendicitis ; Bacteria ; Child ; Diagnosis, Differential ; Emergency Service, Hospital ; Fever ; Gram-Positive Bacteria ; Humans ; Laparoscopy ; Male ; Mucous Membrane ; Sulfur ; Vomiting

Actinomycosis is a slowly progressive, chronic infectious disease. It is caused by the genus Actinomyces, which are gram-positive anaerobic bacteria. It presents as a mass-like lesion, composed of bacterial nidus and characteristic granulomatous inflammatory fibrosis. As such, it has frequently been mistaken for a malignancy. Surgical resection is a common procedure in these patients prior to a definite diagnosis. Although actinomycosis can occur in a variety of regions, including oral-cervicofacial, thoracic, and abdominopelvic cavities, the involvement of the pancreas is very rare. We report a case of a 44-year-old male with a symptomatic actinomycosis caused by a mass in the tail of the pancreas. The diagnosis was made using an endoscopic ultrasound-guided fine needle aspiration biopsy without surgical resection. After the treatment with antibiotics, the pancreatic mass was confirmed to be resolved on the follow-up computed tomography.
Actinomyces ; Actinomycosis* ; Adult ; Anti-Bacterial Agents ; Bacteria, Anaerobic ; Biopsy ; Biopsy, Fine-Needle ; Communicable Diseases ; Diagnosis ; Endoscopic Ultrasound-Guided Fine Needle Aspiration ; Endosonography ; Fibrosis ; Follow-Up Studies ; Humans ; Male ; Pancreas ; Pancreatitis, Chronic* ; Tail