Antimicrobial spiroketal macrolides and dichloro-diketopiperazine from Micromonospora sp. FIMYZ51

Four compounds (1-4) featuring with an L-rhodinose and spiroketal, possess uncommon continuous hydroxy groups in the macrolide skeleton, and a dichloro-diketopiperazine (5) were isolated from a marine derived Micromonospora sp. FIMYZ51. The determination of the relative and absolute configurations of all isolates was achieved by extensive spectroscopic analyses, single-crystal X-ray diffraction analysis, and ECD calculations. According to structural characteristic and genomic sequences, a plausible biosynthetic pathway for compound 1-4 was proposed and a spirocyclase was inferred to be responsible for the formation of the rare spirocyclic moiety. Compounds 1-4 exhibited potent antifungal activities which is equal to itraconazole against Aspergillus niger. Compounds 1-5 exhibited different degree of inhibitory activities against opportunistic pathogenic bacteria of endocarditis (Micrococcus luteus) with MIC values ranging from 0.0625 μg/mL to 32 μg/mL. Compounds 2 and 3 showed moderate cytotoxicity against drug-resistant tumor cell lines (Namalwa and U266). The result not only provides active lead-compounds, but also reveal the potential of the spirocyclase gene resources from Micromonospora sp., which highlights the promising potential of the strain for biomedical applications.

Anti-cancer effects of plant-derived Micromonospora sp. M2 against A549 and MCF-7 cell lines

The huge diversity of secondary bioactive metabolites, such as antibiotic and anticancer compounds produced by Micromonospora sp., makes it an attractive target for study. Here, we explored the anti-proliferative activities of Micromonospora sp. M2 extract (MBE) in relation to its pro-oxidative activities in A549 and MCF7 cell lines. Anti-proliferative effects were assessed by treating cells with MBE. We found that treatment with MBE decreased cell proliferation and increased intracellular reactive oxygen species, and that these observations were facilitated by the suppression of the PI3K-AKT pathway, alterations to the Bcl/Bad ratio, and increased caspase activity. These observations also demonstrated that MBE induced apoptotic cell death in cell lines. In addition, the phosphorylation of P38 and c-Jun N-terminal kinase (JNK) were upregulated following MBE treatment in both cell lines. Collectively, these results indicate that MBE acts as an anticancer agent via oxidative stress and JNK/mitogen-activated protein kinase pathway activation, enhancing apoptotic cell death in cell lines.

Micromonospora cathayae sp. nov., isolated from the rhizosphere soil of Cathaya argyrophylla

A novel actinobacterium, strain HUAS 3T, was isolated from the rhizosphere soil of Cathaya argyrophylla collected in Hunan Province, PR China. Strain HUAS 3T contained meso-diaminopimelic acid in the cell-wall peptidoglycan. The dominant menaquinones were MK-9(H4), MK-9(H6), MK-10(H2) and MK-9(H4). The polar lipids consisted of diphosphatidylglycerol, phospholipids, phosphatidylethanolamine, phosphatidylglycerol, phosphotidylinositol and phosphatidylinositol mannosides. The main cellular fatty acids (>5.0 %) were C17 : 1 ω8c, iso-C16 : 0, C18 : 1 ω9c, iso-C15 : 0, C16 : 0 and summed feature 3 (C16 : 1 ω6c and/or C16 : 1 ω7c). The DNA G+C content of the novel strain's genome sequence, consisting of 7 196 442 bp, was 72.8 mol%. The full-length 16S rRNA gene sequence analysis indicated that strain HUAS 3T belonged to the genus Micromonospora and showed highest similarities to Micromonospora fluminis A38T (99.44 %), Micromonospora echinospora DSM 43816T (99.23 %), Micromonospora tulbaghiae DSM 45142T (99.23 %), Micromonospora solifontis PPF5-17T (99.16 %) and Micromonospora endolithica DSM 44398T (98.96 %). Phylogenetic trees based on 16S rRNA gene sequences showed that strain HUAS 3T was closely related to M. fluminis A38T, M. tulbaghiae DSM 45142T and M. solifontis PPF5-17T. The phylogenomic tree revealed that strain HUAS 3T was closely related to Micromonospora pallida DSM 43817T. However, the average nucleotide identity (ANIb/ANIm) and the digital DNA-DNA hybridization values between them were 84.75 /88.16 and 30.80 %, respectively, far less than the 95-96 and 70 % cut-off points recommended for delineating species. Furthermore, strain HUAS 3T was distinct from the type strain of M. pallida in terms of phenotypic and chemotaxonomic characteristics. In summary, strain HUAS 3T represents a novel Micromonospora species, for which the name Micromonospora cathayae sp. nov. is proposed. The type strain is HUAS 3T (=MCCC 1K08599T=JCM 36275T).

Unveiling growth-promoting attributes of peanut root endophyte Micromonospora sp

In this study, 20 endophytic actinobacteria were isolated from different parts of peanut plants growing in cropland with low and high salt in West Bengal, India. The endophytes underwent a rigorous morphological, biochemical, and genetic screening process to evaluate their effectiveness in enhancing plant growth. About 20% of these isolates were identified as potential plant growth-promoting endophytic actinobacteria, which showed high 16S rRNA gene sequence similarity (up to 99-100%) with different species of Micromonospora. Among these isolates, Micromonospora sp. ASENR15 produced the highest levels of indole acetic acid (IAA) and gibberellic acid (GA), while Micromonospora sp. ASENL2, Micromonospora sp. ANENR4, and Micromonospora sp. ASENR12 produced the highest level of siderophore. Among these leaf and root endophytic Micromonospora, strain ANENR4 was tested for its plant growth-promoting attributes. ANENR4 can be transmitted into the roots of a healthy peanut plant, enhances growth, and colonize the roots in abundance, suggesting the potential agricultural significance of the strain. Moreover, the study is the first report of endophytic Micromonospora in peanuts with PGP effects. The outcomes of this study open avenues for further research on harnessing the benefits of this endophytic Micromonospora for optimizing plant growth in agriculture.

Enhancing La(III) biosorption and biomineralization with Micromonospora saelicesensis: Involvement of phosphorus and formation of monazite nano-minerals

The release of rare earth elements (REEs) from mining wastes and their applications has significant environmental implications, necessitating the development of effective prevention and reclamation strategies. The mobility of REEs in groundwater due to microorganisms has garnered considerable attention. In this study, a La(III) resistant actinobacterium, Micromonospora saelicesensis KLBMP 9669, was isolated from REE enrichment soil in GuiZhou, China, and evaluated for its ability to adsorb and biomineralize La(III). The findings demonstrated that M. saelicesensis KLBMP 9669 immobilized La(III) through the physical and chemical interactions, with immobilization being influenced by the initial La(III) concentration, biomass, and pH. The adsorption kinetics followed a pseudo-second-order rate model, and the adsorption isotherm conformed to the Langmuir model. La(III) adsorption capacity of this strain was 90 mg/g, and removal rate was 94 %. Scanning electron microscope (SEM) coupled with energy dispersive X-ray spectrometer (EDS) analysis revealed the coexistence of La(III) with C, N, O, and P. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) investigations further indicated that carboxyl, amino, carbonyl, and phosphate groups on the mycelial surface may participate in lanthanum adsorption. Transmission electron microscopy (TEM) revealed that La(III) accumulation throughout the M. saelicesensis KLBMP 9669, with some granular deposits on the mycelial surface. Selected area electron diffraction (SAED) confirmed the presence of LaPO4 crystals on the M. saelicesensis KLBMP 9669 biomass after a prolonged period of La(III) accumulation. This post-sorption nano-crystallization on the M. saelicesensis KLBMP 9669 mycelial surface is expected to play a crucial role in limiting the bioimmobilization of REEs in geological repositories.

OSMAC Method to Assess Impact of Culture Parameters on Metabolomic Diversity and Biological Activity of Marine-Derived Actinobacteria

Actinobacteria are known for their production of bioactive specialized metabolites, but they are still under-exploited. This study uses the "One Strain Many Compounds" (OSMAC) method to explore the potential of three preselected marine-derived actinobacteria: Salinispora arenicola (SH-78) and two Micromonospora sp. strains (SH-82 and SH-57). Various parameters, including the duration of the culture and the nature of the growth medium, were modified to assess their impact on the production of specialized metabolites. This approach involved a characterization based on chemical analysis completed with the construction of molecular networks and biological testing to evaluate cytotoxic and antiplasmodial activities. The results indicated that the influence of culture parameters depended on the studied species and also varied in relation with the microbial metabolites targeted. However, common favorable parameters could be observed for all strains such as an increase in the duration of the culture or the use of the A1 medium. For Micromonospora sp. SH-82, the solid A1 medium culture over 21 days favored a greater chemical diversity. A rise in the antiplasmodial activity was observed with this culture duration, with a IC50 twice as low as for the 14-day culture. Micromonospora sp. SH-57 produced more diverse natural products in liquid culture, with approximately 54% of nodes from the molecular network specifically linked to the type of culture support. Enhanced biological activities were also observed with specific sets of parameters. Finally, for Salinispora arenicola SH-78, liquid culture allowed a greater diversity of metabolites, but intensity variations were specifically observed for some metabolites under other conditions. Notably, compounds related to staurosporine were more abundant in solid culture. Consequently, in the range of the chosen parameters, optimal conditions to enhance metabolic diversity and biological activities in these three marine-derived actinobacteria were identified, paving the way for future isolation works.

New Phocoenamicin and Maklamicin Analogues from Cultures of Three Marine-Derived Micromonospora Strains

Antimicrobial resistance can be considered a hidden global pandemic and research must be reinforced for the discovery of new antibiotics. The spirotetronate class of polyketides, with more than 100 bioactive compounds described to date, has recently grown with the discovery of phocoenamicins, compounds displaying different antibiotic activities. Three marine Micromonospora strains (CA-214671, CA-214658 and CA-218877), identified as phocoenamicins producers, were chosen to scale up their production and LC/HRMS analyses proved that EtOAc extracts from their culture broths produce several structurally related compounds not disclosed before. Herein, we report the production, isolation and structural elucidation of two new phocoenamicins, phocoenamicins D and E (1-2), along with the known phocoenamicin, phocoenamicins B and C (3-5), as well as maklamicin (7) and maklamicin B (6), the latter being reported for the first time as a natural product. All the isolated compounds were tested against various human pathogens and revealed diverse strong to negligible activity against methicillin-resistant Staphylococcus aureus, Mycobacterium tuberculosis H37Ra, Enterococcus faecium and Enterococcus faecalis. Their cell viability was also evaluated against the human liver adenocarcinoma cell line (Hep G2), demonstrating weak or no cytotoxicity. Lastly, the safety of the major compounds obtained, phocoenamicin (3), phocoenamicin B (4) and maklamicin (7), was tested against zebrafish eleuthero embryos and all of them displayed no toxicity up to a concentration of 25 μM.

1-(6-Methylsalicyloyl)glycerol from stony coral-derived Micromonospora sp

A new natural product, 1-(6-methylsalicyloyl)glycerol (1) was isolated from the culture extract of the stony coral-derived Micromonospora sp. C029. The structure of 1 was determined by extensive analysis of 1D and 2D NMR spectroscopic data. The absolute configuration was determined to be S by comparison of specific rotation with synthetic (R)- and (S)-1. Compound 1 showed weak antimicrobial activity against Kocuria rizhophila. Structurally related benzoyl glycerol is not reported from actinomycetes, suggesting that isolation of actinomycetes from little studied environments should be important for the discovery of novel natural products.

Descriptions of Micromonospora grosourdyae nom. nov., Micromonospora sonchi comb. nov. and Micromonospora thawaii sp. nov. to resolve problems with the taxonomy and nomenclature of strains named Micromonospora endophytica

The name Micromonospora endophytica has been used for three different organisms. The first organism with this name is the species represented by strain DCWR9-8-2^T, a species published in 2015 but whose name was never validated. In 2019 the type species of the genus Jishengella was reclassified into the genus Micromonospora, while maintaining its original epithet, thus establishing the second group of organisms known as M. endophytica, but the first for which the name was validated. Additionally, in 2018 the reclassification of the genus Verrucosispora into the genus Micromonospora was proposed, but a new epithet has not been specified for the species named Verrucosispora endophytica, which remains an orphaned species. Therefore, it is necessary to propose new names that can unequivocally identify these taxa. We have analysed the taxonomic position of the strains, comparing them with the species with valid published names of the genus Micromonospora. We here propose Micromonospora thawaii sp. nov. for the species represented by strain DCWR9-8-2^T, and Micromonospora grosourdyae nom. nov. and Micromonospora sonchi comb. nov. for the two orphaned species of Verrucosispora, V. endophytica and Verrucosispora sonchi, respectively. Genomic analysis also showed that M. trujilloniae is a later heterotypic synonym of M. andamanensis.

Micromonospora metallophores: A plant growth promotion trait useful for bacterial-assisted phytoremediation?

Heavy metal pollution in the environment is an increasing problem due to natural and anthropogenic activities. The use of bacteria for bioremediation of soils contaminated with heavy metals has gained a lot of attention as it can be considered effective, economic and environmentally sustainable. In this work, we investigated the capacity of endophytic Micromonospora strains isolated from different legumes, to produce metallophores against a variety of heavy metals in vitro. Genome mining using available endophytic Micromonospora genome sequences revealed the presence of genes related to metal acquisition, iron metabolism and resistance to toxic compounds. In vitro production of metallophores demonstrated that all strains tested produced chelates against arsenic, cobalt, copper, chromium, iron, mercury, molybdenum, nickel, vanadium and zinc in different amounts. In addition, the plant growth promotion effect of strains GAR05 and PSN13 on Arabidopsis thaliana grown in the presence of several heavy metals was tested. Under these conditions, the plants inoculated with the strain GAR05 showed significant growth when compared to the control plants suggesting a plant growth promotion effect in the form of tolerance to the toxic substances. Furthermore, during this plant-bacterium interaction, a new bacterial structure named root-bead was observed on the roots of A. thaliana suggesting a strong interaction between the two organisms and a clear positive effect of the bacterium on the plant. Overall, these results highlight the potential use of endophytic Micromonospora strains for bacterial-assisted phytoremediation of contaminated sites.

Actinoplanes solisilvae sp. nov., Isolated from Birch Forest Soil

A novel actinomycete, designated strain LAM7112^T, was isolated from soil sample collected from a birch forest in Xinjiang Uygur Autonomous Region, China. The new isolate was found to be able to grow at 20-45 °C (optimum: 35 °C), pH 5.0-10.0 (optimum: 7.0) and in the presence of 0-10.0% (optimum: 3.0%) (w/v) NaCl. The isolate formed very scantily irregular sporangia containing motile spores on the substrate mycelium. Phylogenetic analysis of 16S rRNA gene sequences indicated that the new isolate was closely related to members of the family Micromonosporaceae, with highest similarites to Actinoplanes ferrugineus X-14695^T (97.4%), Micromonospora zamorensis DSM 45600^T (97.3%) and Micromonospora aurantiaca ATCC 27029^T (97.3%). In the phylogenetic trees, strain LAM7112^T formed a stable phylogenetic subclade within the genus Actinoplanes. The genomic DNA G + C content was 70.0 mol%. The major fatty acids (> 10%) were determined to be iso-C_16:0, anteiso-C_15:0 and anteiso-C_17:0. The predominant menaquinones were identified as MK-9 (H₂), MK-9 (H₄) and MK-9 (H₆). The major polar lipids were found to be diphosphatidylglycerol, phosphatidylinositol and phosphatidylethanolamine. The diagnostic amino acid of the cell wall peptidoglycan was determined to be meso-diaminopimelic acid. The diagnostic sugars in cell hydrolysates were determined to be glucose and ribose. On the basis of its phenotypic, phylogenetic and chemotaxonomic characteristics, strain LAM7112^T (= CGMCC 4.7580^T = JCM 32512^T) is proposed to represent the type strain of a novel species of the genus Actinoplanes, for which the name Actinoplanes solisilvae is proposed.

Bioactive naphthoquinone and anthrone derivatives from endophytic Micromonospora sp. NEAU-gq13

Two new naphthalenone derivatives, 5-hydroxy-4-oxo-2-(2-oxopropyl)-1,2,3,4-tetrahydronaphthalen-1-yl acetate (1) and 5-hydroxy-2-(2-hydroxypropyl)naphthalene-1,4-dione (2), together with two new anthrone derivatives, (S)-2,5-dihydroxy-2-methyl-1,2,3,4-tetrahydroanthracene-9,10-dione (3) and 4,5-dihydroxy-2-methyl-9H-xanthen-9-one (4), were isolated from the fermentation broth of endophytic Micromonospora sp. NEAU-gq13. Their structures were determined by 1D-NMR, 2D-NMR, and HR-ESI-MS analysis. Compounds 2 and 3 exhibited strong cytotoxic activity against human central nervous system cancer (SF-268) with the IC₅₀ values of 3.04 and 5.66 μg/ml, respectively. Moreover, compound 2 also displayed potent activity against human liver cancer (HepG2) with an IC₅₀ value of 1.01 μg/ml.

R176502, a New Bafilolide Metabolite with Potent Antiproliferative Activity from a Novel Micromonospora Species

During the course of a screening program intended to identify new antiproliferative agents, a new bafilolide metabolite was discovered. R176502 (1) was isolated from the liquid fermentation cultures of a novel Micromonospora species found in African river bottom sediment. It was purified from ethyl acetate extracts using a series of countercurrent chromatographic steps. The structure was determined using 1- and 2-D NMR experiments. Three previously described bafilomycins (bafilomycins A1 (2), B1 (3), and B2 (4)) were also isolated (from other microbial strains). R176502 exhibited potency for inhibition of tumor cell proliferation in the nM range of concentrations.

SB-219383, a novel tyrosyl tRNA synthetase inhibitor from a Micromonospora sp. I. Fermentation, isolation and properties

A novel, potent and selective inhibitor of bacterial tyrosyl tRNA synthetase, designated SB-219383 has been isolated from Micromonospora sp. NCIMB 40684. The fermentation, isolation and some properties are described, whilst the structure determination is described in the succeeding paper). SB-219383 showed competitive, inhibitory activity against a Staphylococcus tyrosyl tRNA synthetase, with an IC50 of <1 nM, and exhibited weak in vitro activity against some Streptococcus sp.

SB-219383, a novel tyrosyl tRNA synthetase inhibitor from a Micromonospora sp. II. Structure determination

A novel tyrosyl tRNA synthetase inhibitor, SB-219383, has been isolated from a Micromonospora sp. The structure of SB-219383 has been elucidated by a combination of derivatisation, spectroscopic and other analytical techniques and found to be N-(L-tyrosyl)-2-amino[1(S*),3(S*),4(S*),5(R*),8(R*)-2,4,5,8-tetrahydroxy -7-oxa-2-azabicyclo[3.2.1]oct-3-y1]acetic acid (1).

Thiocoraline, a new depsipeptide with antitumor activity produced by a marine Micromonospora. I. Taxonomy, fermentation, isolation, and biological activities

A novel bioactive depsipeptide, thiocoraline, was isolated from the mycelial cake of a marine actinomycete strain L-13-ACM2-092. Based on morphological, cultural, physiological, and chemical characteristics, strain L-13-ACM2-092 was ascribed to the genus Micromonospora. Thiocoraline showed a potent cytotoxic activity against P-388, A-549 and MEL-28 cell lines, and also a strong antimicrobial activity against Gram-positive microorganisms. This compound binds to supercoiled DNA and inhibits RNA synthesis.

ANTIGENIC STRUCTURE OF THE ACTINOMYCETALES. VII. CHEMICAL AND SEROLOGICAL SIMILARITIES OF CELL WALLS FROM 100 ACTINOMYCETALES STRAINS

Kwapinski, J. B. (The University of New England, Armidale, Australia). Antigenic structure of the Actinomycetales. VII. Chemical and serological similarities of cell walls from 100 Actinomycetales strains. J. Bacteriol. 88:1211-1219. 1964.-Cell walls prepared mechanically from 100 strains of Actinomycetales were studied by chromatographic and serological methods. The cell walls of Actinomyces were found to be serologically related to those of the corynebacteria and to some strains of mycobacteria and nocardiae. The cell walls of nocardiae appeared to be more closely related to those of the mycobacteria, Streptomyces, Micromonospora, and Waksmania. The cell walls of Micromonospora and Waksmania showed certain serological similarities to those of Thermoactinomyces and nocardiae. Micropolyspora was antigenically different from other species of the Actinomycetales. Three serological groups of mycobacteria and four groups of nocardiae were distinguished.

CHEMICAL COMPOSITION OF CELL-WALL PREPARATIONS FROM STRAINS OF VARIOUS FORM-GENERA OF AEROBIC ACTINOMYCETES

Cell-wall preparations were made from more than 140 strains of aerobic actinomycetes representing most of the form-genera that have been proposed. All cell-wall preparations contained as major constituents glucosamine, muramic acid, alanine, and glutamic acid. In addition, cell-wall preparations from various types of streptomycetes and strains of Microëllobosporia contained glycine and ll-alpha,epsilon-diaminopimelic acid; those from strains of most Actinoplanaceae and micromonosporae contained glycine and meso-alpha-epsilon-diaminopimelic acid; those from strains of Thermoactinomyces, Microbispora, Dermatophilus, and nocardiae of the madurae-pelletieri group contained meso-alpha,epsilon-diaminopimelic acid; and those from strains of Thermomonospora, Micropolyspora, and most nocardiae contained meso-alpha,epsilon-diaminopimelic acid, arabinose, and galactose. All the strains used were also studied morphologically.

CHEMISTRY OF ANTIBIOTICS FROM MICROMONOSPORA. 3. ISOLATION AND CHARACTERIZATION OF EVERNINOMICIN D AND B

The isolation of everninomicin D and everninomicin B, two closely related antibiotics produced by Micromonospora carbonacea, is described. The structures of everninomicin D and B are shown to parallel closely that of curamycin, a polysaccharidic antibiotic with a low molecular weight and a dichloroisoeverninic acid end group.

MS-444, a new inhibitor of myosin light chain kinase from Micromonospora sp. KY7123

A novel compound MS-444 was isolated from the culture broth of a bacterial strain KY7123. The strain was identified as Micromonospora sp. from its morphological and cultural characteristics. The compound inhibited the activity of purified smooth muscle myosin light chain kinase with an IC50 value of 10 microM. The production, isolation, physico-chemical properties and biological activities of MS-444 were described in this paper.

Macquarimicins, microbial metabolites from Micromonospora. I. Discovery, taxonomy, fermentation and biological properties

A novel series of microbial metabolites were discovered in fermentation broths of two soil isolates. Both cultures were identified as strains of Micromonospora chalcea. Production of the metabolites, named macquarimicins, was monitored by an HPLC assay. A seven-day fermentation yielded 27 mg/liter of macquarimicin A. With MICs of 50 to 100 micrograms/ml, macquarimicin A has only very low activity against strains of Bacteroides and other anaerobes. Macquarimicin B has inhibitory activity against the leukemia cell line P-388.

Characterization of a temperate actinophage, MPphiWR-1, capable of infecting Micromonospora purpurea ATCC 15835

A temperate actinophage was isolated from soil using the gentamicin-producing microorganism, Micromonospora purpurea ATCC 15835 as host. The characterization of the phage represents the initial step in its development as a cloning vector. The phage isolated, MPphiWR-1, formed red- to purple-pigmented turbid plaques. Cells isolated from these plaques were resistant to superinfection with lytic mutants of MPphiWR-1. Southern blots of genomic DNA from a resistant culture showed that MPphiWR-1 integrated into the host genome. The phage was UV- or Mitomycin C-inducible. The integration, resistance to superinfection and inducibility indicated a lysogenic relationship with the host. Using MPphiE-RCPM, a lytic derivative, the phage host range was demonstrated to include members of three genera: one species each of Ampullariella and Catellatospora, and 12 species of Micromonospora. The phage belonged to Ackerman's B1 morphotype having an isometric head and a flexible noncontractile tail. The density of the phage was 1.525 g/cc. Restriction site mapping demonstrated that the phage DNA was 57.9 kb long and had cohesive ends. Using EDTA enrichment, viable mutants with deletions of at least 3.5 kb were isolated and mapped. Phage adsorption, sensitivities and plating efficiency were investigated. Non-liposome PEG-mediated transfection was demonstrated.

[Studies on actinomycete flora and resources in the plateau lakes in Yunnan]

During the period of 1983 to 1987 mud and water samples were collected from 12 larger lakes on the Yunnan Plateau. The actinomycetes in both sediment and water samples were investigated. Strains producing metabolites were screened by various procedures. The results are as follow: 1. The number and composition of actinomycetes in a lake were found to have relation to the physical and chemical features of the water-body. On the basis of the number and generic diversity of actinomycetes, lakes were thus divided into four groups. 2. Micromonospora occupied a notable domonance in benthic samples taken from all 12 lakes. This is a conspicuous characteristics of actinomycete flora in these lakes. 3. The population of actinomycetes in Lakes Qilu, Yilong and Datun ranges from 2991 to 3542 X 10(3)/g dry wt. of mud. 4. Strains of Actinomadura, Microtetraspora, Micropolyspora, Saccharomonospora and Saccharopolyspora were isolated. These genera were not previously reported in similar studies abroad. In addition, five species were considered to be new to science: Micromonospora phaeovirida Jiang et Xu, 1985 Saccharomonospora yunnanensis Jiang et Xu, 1985 Microtetraspora flavorosea Jiang et Xu, 1986 Actinomadura chenghaiensis Jiang et Xu, 1986 Actinomadura viridoflava Jiang et Xu, 1986 5. Studies indicate that actinomycetes possibly play an important role in the decomposition of chitin, cellulose and some toxic substances in lakes. 6. As freshwater resources, actinomycetes produce various useful metabolites such as fibrinolysine, and milk-clotting enzyme.

The structure of M-GTFI, an inhibitor of glucosyltransferase from S. mutans, and its inhibitory relationship with other sulfate ester-containing inhibitors

M-GTFI, an inhibitor of glucosyltransferase from S. mutans was produced by Micromonospora narashinoensis strain No. 731. The isolation procedure for M-GTFI was improved and established for spectroscopic analyses, and some properties of the inhibitor were investigated. The structure of M-GTFI was shown to be trisodium [2-sulphonato-(E)-9-undecenyll-oxacyclotriacont-(E)-3- en-2-one, 16, 18-bis sulphonate. The chemical structure of M-GTFI was therefore similar to that of izumenolide which is a beta-lactamase inhibitor containing sulfate ester groups in its molecule. The inhibitory characteristics of M-GTFI were parallel to that of other inhibitory compounds containing sulphate esters but the spectrum of activity was wider.

K-13, a novel inhibitor of angiotensin I converting enzyme produced by Micromonospora halophytica subsp. exilisia. II. Structure determination

The structure of K-13, a potent inhibitor of angiotensin I converting enzyme (ACE), was determined to be a cyclic dipeptide composed of tyrosine and an unusual diamino dicarboxylic acid, isodityrosine, by spectral and chemical studies of K-13 and its derivatives.

Characteristics of bacteriophages for Micromonospora purpurea

Chemical and physical stabilities of bacteriophages øUW 21 and øUW 51 infecting Micromonospora purpurea ATCC 15835 were examined. Both phages were stable over the pH range of 5 to 8 and to heating at temperatures up to 50 degrees C and especially stable in buffer containing magnesium ion. Exposure to 1 M Ca(NO3)2 inactivated both phages, and phage øUW 51 was also susceptible to 1 M CaCl2, 0.1 M tris(hydroxymethyl)aminomethane, and 0.3% H2O2. Phage plating efficiency was highest on the cultures at logarithmic phase and sometimes much influenced by host growth. Phage øUW 51 has a latent period of 2 h at 34 degrees C and a burst size between 35 and 40. The latent period for phage øUW 21 is about 12 h, and the burst size is smaller than 30.

Macrolide antibiotics M-4365 produced by Micromonospora. III. In vitro antimicrobial activity of antibiotic M-4365G2 (de-epoxy rosamicin)

Antibiotic M-4365G2 (de-epoxy rosamicin) produced by Micromonospora capillata MCRL 0940 is a new basic 16-membered macrolide antibiotic with activity equal to or superior to erythromycin and josamycin against Gram-positive bacteria. Of interest are the high degree of activity against Gram-negative bacilli and mycoplasmas, and striking inhibitory effects against indole-producing Proteus spp. Bactericidal activity of M-4365G2 is also to be noticed.

Protoplasts of Trichoderma viride: formation and regeneration

High yields of protoplasts from the 18-hr old mycelium of Trichoderma viride were obtained by using the lytic system, produced by Streptomyces venezuelae RA and Micromonospora chalcea grown on a synthetic medium containing laminarin and chitin, when 0.7 M MgSO4 or (NH4)2SO4 were used as osmotic stabilizers. Regeneration of these protoplasts occurred through the production of an abortive tube and direct germination of the protoplasts. Regeneration could also take place in the medium used to produce protoplasts, but the process was different in many details.

PRODUCTION OF YEAST AND MOLD PROTOPLASTS BY TREATMENT WITH THE STREPZYME OF MICROMONOSPORA AS

Using phase microscopy, the authors made studies of the formation and properties of spherical protoplasts of the organisms Candida utilis, Oospora suaveolens, and Geotrichum lactis, produced by digestion of the cell walls in isotonic medium with a lytic preparation obtained from the filtrates of the growth medium of Micromonospora AS. The susceptibility of various species of yeast and molds to cell wall digestion and further liberation of protoplasts was variable. MgSO4 (0.8 to 1.0 M final concentration) was a satisfactory stabilizer for producing osmotically sensitive spherical bodies. On dilution, these fragile structures lysed immediately. The naked protoplasts were able to grow, as indicated by changes in morphology. On prolonged incubation abnormal cells were formed. Reversion to normal cells was observed but was very rare. Details of the emergence of the Oospora suaveolens protoplasts were described. Protoplasts were also prepared from a variety of bacteria.

COMPARISON OF THE CELL-WALL COMPOSITION OF MORPHOLOGICALLY DISTINCT ACTINOMYCETES

Yamaguchi, Tatsuro (The University of Tokyo, Tokyo, Japan). Comparison of the cell-wall composition of morphologically distinct actinomycetes. J. Bacteriol. 89:444-453. 1965.-Cell-wall composition of various morphologically distinct actinomycetes was studied to determine the relationship, if any, between cell-wall composition and morphological criteria in actinomycete taxonomy. The methods used were similar to those of Cummins and Harris. At least five types of cell-wall composition were obtained; however, these were not always correlated with groupings by the conventional classification system. For instance, the sporangium-forming actinomycetes, Actinoplanaceae, had three types of cell-wall composition; the composition of cell walls of Promicromonospora, Micromonospora, and Microbispora was the same as, or similar to, that of Actinomyces, Actinoplanes, and Streptosporangium, respectively; Chainia, Actinopycnidium, Actinosporangium, and Microellobosporia had the same cell-wall composition as Streptomyces, whereas that of Streptoverticillium was slightly different. Possible implications of cell-wall composition and morphological differentiation of hyphae for the taxonomy and phylogeny of actinomycetes are also discussed.