Killing of Mycolic Acid-Containing Bacteria Aborted Induction of Antibiotic Production by Streptomyces in Combined-Culture.

Co-culture of Streptomyces with mycolic acid-containing bacteria (MACB), which we termed "combined-culture," alters the secondary metabolism pattern in Streptomyces and has been a useful method for the discovery of bioactive natural products. In the course of our investigation to identify the inducing factor(s) of MACB, we previously observed that production of pigments in Streptomyces lividans was not induced by factors such as culture extracts or mycolic acids. Although dynamic changes occurred in culture conditions because of MACB, the activation of pigment production by S. lividans was observed in a limited area where both colonies were in direct contact. This suggested that direct attachment of cells is a requirement and that components on the MACB cell membrane may play an important role in the response by S. lividans. Here we examined whether this response was influenced by dead MACB that possess intact mycolic acids assembled on the outer cell membrane. Formaldehyde fixation and γ-irradiation were used to prepare dead cells that retain their shape and mycolic acids of three MACB species: Tsukamurella pulmonis, Rhodococcus erythropolis, and Rhodococcus opacus. Culturing tests verified that S. lividans does not respond to the intact dead cells of three MACB. Observation of combined-culture by scanning electron microscopy (SEM) indicated that adhesion of live MACB to S. lividans mycelia were a significant interaction that resulted in formation of co-aggregation. In contrast, in the SEM analysis, dead cells were not observed to adhere. Therefore, direct attachment by live MACB cells is proposed as one of the possible factors that causes Streptomyces to alter its specialized metabolism in combined-culture.

Geodermatophilus sabuli sp. nov., a γ-radiation-resistant actinobacterium isolated from desert limestone.

A novel γ-radiation-resistant and Gram-staining-positive actinobacterium designated BMG 8133T was isolated from a limestone collected in the Sahara desert of Tunisia. The strain produced dry, pale-pink colonies with an optimum growth at 35­40 °C and pH 6.5­8.0. Chemotaxonomic and molecular characteristics of the isolate matched those described for members of the genus Geodermatophilus. The peptidoglycan contained meso-diaminopimelic acid as diagnostic diamino acid. The main polar lipids were phosphatidylcholine, diphosphatidylglycerol, phosphatidylinositol, phosphatidylethanolamine and one unspecified glycolipid. MK-9(H4) was the dominant menaquinone. Galactose and glucose were detected as diagnostic sugars. The major cellular fatty acids were branched-chain saturated acids iso-C16 : 0 and iso-C15 : 0. The DNA G+C content of the novel strain was 74.5 %. The 16S rRNA gene sequence showed highest sequence identity with Geodermatophilus ruber (98.3 %). Based on phenotypic results and 16S rRNA gene sequence analysis, strain BMG 8133T is proposed to represent a novel species, Geodermatophilus sabuli sp. nov. The type strain is BMG 8133T ( = DSM 46844T = CECT 8820T).

Description of gamma radiation-resistant Geodermatophilus dictyosporus sp. nov. to accommodate the not validly named Geodermatophilus obscurus subsp. dictyosporus (Luedemann, 1968).

A gamma radiation-resistant, Gram reaction-positive, aerobic and chemoorganotrophic actinobacterium, initially designated Geodermatophilus obscurus subsp. dictyosporus G-5(T), was not validly named at the time of initial publication (1968). G-5(T) formed black-colored colonies on GYM agar. The optimal growth range was 25-35 °C, at pH 6.5-9.5 and in the absence of NaCl. Chemotaxonomic and molecular characteristics of the isolate matched those described for members of the genus Geodermatophilus. The DNA G + C content of the strain was 75.3 mol%. The peptidoglycan contained meso-diaminopimelic acid as diagnostic diamino acid. The main polar lipids were phosphatidylcholine, diphosphatidylglycerol, phosphatidylinositol, phosphatidylethanolamine and one unspecified glycolipid; MK-9(H4) was the dominant menaquinone and galactose was detected as a diagnostic sugar. The major cellular fatty acids were branched-chain saturated acids, iso-C16:0 and iso-C15:0. The 16S rRNA gene showed 94.8-98.4 % sequence identity with the members of the genus Geodermatophilus. Based on phenotypic results and 16S rRNA gene sequence analysis, strain G-5(T) is proposed to represent a novel species, Geodermatophilus dictyosporus and the type strain is G-5(T) (=DSM 43161(T) = CCUG 62970(T) = MTCC 11558(T) = ATCC 25080(T) = CBS 234.69(T) = IFO 13317(T) = KCC A-0154(T) = NBRC 13317(T)). The INSDC accession number is HF970584.

Deep sequencing analysis of the Kineococcus radiotolerans transcriptome in response to ionizing radiation.

Kineococcus radiotolerans is a gram-positive, radiation-resistant bacterium that was isolated from a radioactive environment. The synergy of several groups of genes is thought to contribute to the radio-resistance of this species of bacteria. Sequencing of the transcriptome, RNA sequencing (RNA-seq), using deep sequencing technology can reveal the genes that are differentially expressed in response to radiation in this bacterial strain. In this study, the transcriptomes of two samples (with and without irradiation treatment) were sequencing by deep sequencing technology. After the bioinformatics process, 143 genes were screened out by the differential expression (DE) analysis. In all 143 differentially expressed genes, 20 genes were annotated to be related to the radio-resistance based on the cluster analysis by the cluster of orthologous groups of proteins (COG) annotation which were validated by the quantitative RT-PCR. The pathway analysis revealed that these 20 validated genes were related to DNA damage repair, including recA, ruvA and ruvB, which were considered to be the key genes in DNA damage repair. This study provides the foundation to investigate the regulatory mechanism of these genes.

The cellulolytic system of Thermobifida fusca.

The process of bioethanol production from biomass comprises pretreatments and enzyme-mediated hydrolysis to convert lignocellulose into fermentable sugars. Because of the recalcitrant character of cellulose, the enzymatic hydrolysis is considered the major challenge in this process to be economically competitive. These technical difficulties highlight the need for the discovery of new enzymes to optimize and lower the cost of current technologies. Microorganisms have developed efficient systems for cellulose degradation. Among cellulolytic microbes, Thermobifida fusca possesses great physiological and cellulolytic characteristics (thermostability, high activity and tolerance to a broad pH range) making it an interesting organism to be studied from an applied perspective. In this review we describe the main enzymes/proteins produced by T.fusca (cellulases, xylanases, mannanase, manosidase, CBM33 and CelR), the effect of substrate on T. fusca proteome, enzyme improvement approaches, synergism between enzymes/proteins and artificial cellulosomes.

The effect of microdosimetric 12C6+ heavy ion irradiation and Mg2+ on canthaxanthin production in a novel strain of Dietzia natronolimnaea.

BACKGROUND: Dietzia natronolimnaea is one of the most important bacterial bioresources for high efficiency canthaxanthin production. It produces the robust and stable pigment canthaxanthin, which is of special interest for the development of integrated biorefineries. Mutagenesis employing 12C6+ irradiation is a novel technique commonly used to improve microorganism productivity. This study presents a promising route to obtaining the highest feasible levels of biomass dry weight (BDW), and total canthaxanthin by using a microdosimetric model of 12C6+ irradiation mutation in combination with the optimization of nutrient medium components. RESULTS: This work characterized the rate of both lethal and non-lethal dose mutations for 12C6+ irradiation and the microdosimetric kinetic model using the model organism, D. natronolimnaea svgcc1.2736. Irradiation with 12C6+ ions resulted in enhanced production of canthaxanthin, and is therefore an effective method for strain improvement of D. natronolimnaea svgcc1.2736. Based on these results an optimal dose of 0.5-4.5 Gy, Linear energy transfer (LET) of 80 keV µm-1and energy of 60 MeV u-1 for 12C6+ irradiation are ideal for optimum and specific production of canthaxanthin in the bacterium. Second-order empirical calculations displaying high R-squared (0.996) values between the responses and independent variables were derived from validation experiments using response surface methodology. The highest canthaxanthin yield (8.14 mg) was obtained with an optimized growth medium containing 21.5 g L-1 D-glucose, 23.5 g L-1 mannose and 25 ppm Mg2+ in 1 L with an irradiation dose of 4.5 Gy. CONCLUSIONS: The microdosimetric 12C6+ irradiation model was an effective mutagenic technique for the strain improvement of D. natronolimnaea svgcc1.2736 specifically for enhanced canthaxanthin production. At the very least, random mutagenesis methods using 12C6+ions can be used as a first step in a combined approach with long-term continuous fermentation processes. Central composite design-response surface methodologies (CCD-RSM) were carried out to optimize the conditions for canthaxanthin yield. It was discovered D-glucose, Mg2+ and mannose have significant influence on canthaxanthin biosynthesis and growth of the mutant strain.

Geodermatophilus tzadiensis sp. nov., a UV radiation-resistant bacterium isolated from sand of the Saharan desert.

Three novel Gram-positive, aerobic, actinobacterial strains, CF5/2(T), CF5/1 and CF7/1, were isolated in 2007 during environmental screening of arid desert soil in the Sahara desert, Chad. Results from riboprinting, MALDI-TOF protein spectra and 16S rRNA sequence analysis confirmed that all three strains belonged to the same species. Phylogenetic analysis of 16S rRNA sequences with the strains' closest relatives indicated that they represented a distinct species. The three novel strains also shared a number of physiological and biochemical characteristics distinct from previously named Geodermatophilus species. The novel strains' peptidoglycan contained meso-diaminopimelic acid; their main phospholipids were phosphatidylcholine, phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylinositol and a small amount of phosphatidylglycerol; MK-9(H4) was the dominant menaquinone. The major cellular fatty acids were the branched-chain saturated acids iso-C16:0 and iso-C15:0. Galactose was detected as diagnostic sugar. Based on these chemotaxonomic results, 16S rRNA gene sequence analysis and DNA-DNA hybridization between strain CF5/2(T) and the type strains of Geodermatophilus saharensis, Geodermatophilus arenarius, Geodermatophilus nigrescens, Geodermatophilus telluris and Geodermatophilus siccatus, the isolates CF5/2(T), CF5/1 and CF7/1 are proposed to represent a novel species, Geodermatophilus tzadiensis, with type strain CF5/2(T)=DSM 45416=MTCC 11411 and two reference strains, CF5/1 (DSM 45415) and CF7/1 (DSM 45420).

Metabolic roles of carotenoid produced by non-photosynthetic bacterium Gordonia alkanivorans SKF120101.

Carotenoids produced by non-photosynthetic bacteria protect organisms against lethal photodynamic reactions and scavenge oxygenic radicals. However, the carotenoid produced by Gordonia alkanivorans SKF120101 is coupled to reducing power generation. SKF120101 selectively produces carotenoid under light conditions. The growth yield of SKF120101 cultivated under light conditions was higher than that under dark condition. In the cyclic voltammetry, both upper and lower voltammograms for neutral red (NR) immobilized in intact cells of SKF120101 were not shifted in the condition without external redox sources but were commonly shifted downward by glucose addition and light. Electric current generation in a biofuel cell system (BFCS) catalyzed by harvested cells of SKF120101 was higher under light than dark condition. The ratio of electricity generation to glucose consumption by SKF120101 cultivated in BFCS was higher under light than dark condition. The carotenoid produced by SKF120101 catalyzes production of reducing power from light energy, first evaluated by the electrochemical technique used in this research.

Contrasted resistance of stone-dwelling Geodermatophilaceae species to stresses known to give rise to reactive oxygen species.

Stones in arid environments are inhabited by actinobacteria of the family Geodermatophilaceae like the genera Blastococcus and Modestobacter frequently isolated from altered calcarenites. Their habitat requires adaptation to light-induced and other stresses that generate reactive oxygen species. Here, we show that representative members of the species Blastococcus saxobsidens, Geodermatophilus obscurus, and Modestobacter multiseptatus are differentially adapted to stresses associated with arid environments. Whereas B. saxobsidens was found to be sensitive to gamma radiation (D(10)  = 900 Gy; 10% survival at 900 Gy), M. multiseptatus was moderately (D(10)  = 6000 Gy) and G. obscurus was highly tolerant (D(10)  = 9000 Gy). A difference in resistance to high-frequency (λ value = 254 nm) UV was shown by B. saxobsidens, M. multiseptatus, and G. obscurus, being sensitive, tolerant, and highly tolerant (D(10) of 6, 900, and > 3500 kJ m(-2) , respectively). Tolerance to desiccation, mitomycin C and hydrogen peroxide correlated with the ionizing radiation and UV resistance profiles of the three species and were correlated with the pigments synthesized. Resistance to heavy metals/metalloids did not follow the same pattern, with resistance to Ag(2+) and Pb(2+) being similar for B. saxobsidens, M. multiseptatus, and G. obscurus, whereas resistance to AsO4 3-, Cr(2+) , or Cu(2+) was greater for B. saxobsidens than for the other two species. The stress resistance profiles of M. multiseptatus and B. saxobsidens were reflected in different calcarenite colonization patterns. While M. multiseptatus was predominantly isolated from the first two millimeters of stone surface, B. saxobsidens was predominantly isolated from the deeper part of the stone where it is better protected from sun irradiation, suggesting that the response to light- and desiccation-induced oxidative stress is an important driver for niche colonization in the stone biotope.

Colonization of tomato seedlings by bioluminescent Clavibacter michiganensis subsp. michiganensis under different humidity regimes.

Tomato bacterial canker, caused by Clavibacter michiganensis subsp. michiganensis, is transmitted by infected or infested seed and mechanically from plant to plant. Wounds occurring during seedling production and crop maintenance facilitate the dissemination of the pathogen. However, the effects of environmental factors on C. michiganensis subsp. michiganensis translocation and growth as an endophyte have not been fully elucidated. A virulent, stable, constitutively bioluminescent C. michiganensis subsp. michiganensis strain BL-Cmm 17 coupled with an in vivo imaging system allowed visualization of the C. michiganensis subsp. michiganensis colonization process in tomato seedlings in real time. The dynamics of bacterial infection in seedlings through wounds were compared under low (45%) and high (83%) relative humidity. Bacteria multiplied rapidly in cotyledon petioles remaining after clip inoculation and moved in the stem toward both root and shoot. Luminescent signals were also observed in tomato seedling roots over time, and root development was reduced in inoculated plants maintained under both humidity regimes. Wilting was more severe in seedlings under high-humidity regimes. A strong positive correlation between light intensity and bacterial population in planta suggests that bioluminescent C. michiganensis subsp. michiganensis strains will be useful in evaluating the efficacy of bactericides and host resistance.

Ultraviolet-radiation-resistant isolates revealed cellulose-degrading species of Cellulosimicrobium cellulans (UVP1) and Bacillus pumilus (UVP4).

Among extremophiles, microorganisms resistant to ultraviolet radiation (UVR) have been known to produce a variety of metabolites (i.e., extremolytes). We hypothesized that natural microbial flora on elevated land (hills) would reveal a variety of UVR-resistant extremophiles and polyextremophiles with modulated proteins and enzymes that had biotechnological implications. Microorganisms Cellulosimicrobium cellulans UVP1 and Bacillus pumilus UVP4 were isolated and identified using 16S rRNA sequencing, and showed extreme UV resistance (1.03 × 106 and 1.71 × 105 J/m², respectively) from elevated land soil samples along with unique patterns of protein expression under UVR and non-UVR. A broad range of cellulolytic activity on carboxymethyl cellulose agar plates in C. cellulans UVP1 and B. pumilus UVP4 was revealed at varying pH, temperature, and inorganic salt concentration. Further, the microbial strain B. pumilus UVP4 showed the basic characteristics of a novel group: polyextremophiles with significance in bioenergy.

Microbacterium radiodurans sp. nov., a UV radiation-resistant bacterium isolated from soil.

Strain GIMN 1.002(T), a UV radiation-tolerant bacterium, was isolated from the upper sand layers of the Gobi desert, Xinjiang, China and characterized in order to determine its taxonomic position. Cells were Gram-reaction-positive, heterotrophic, strictly aerobic, short rods. 16S rRNA gene sequence analysis revealed that strain GIMN 1.002(T) belonged to the genus Microbacterium and was closely related to Microbacterium arborescens DSM 20754(T) (98.8 % 16S rRNA gene sequence similarity) and Microbacterium imperiale DSM 20530(T) (98.7 %). However, strain GIMN 1.002(T) had low DNA-DNA relatedness with M. arborescens DSM 20754(T) (17.1 %) and M. imperiale DSM 20530(T) (12.89 %). Strain GIMN 1.002(T) possessed chemotaxonomic markers that were consistent with its classification in the genus Microbacterium, i.e. MK-11, MK-12 and MK-10 as major menaquinones and anteiso-C(15 : 0) (38.67 %), iso-C(16 : 0) (18.16 %) and iso-C(15 : 0) (17.46 %) as predominant cellular fatty acids. The DNA G+C content was 67.74 mol%. The cell-wall sugar was rhamnose. On the basis of the data from this study, strain GIMN 1.002(T) represents a novel species of the genus Microbacterium, for which the name Microbacterium radiodurans sp. nov. is proposed. The type strain is GIMN 1.002(T) (=CCTCC M208212(T) =NRRL B-24799(T)).

Survival in nuclear waste, extreme resistance, and potential applications gleaned from the genome sequence of Kineococcus radiotolerans SRS30216.

Kineococcus radiotolerans SRS30216 was isolated from a high-level radioactive environment at the Savannah River Site (SRS) and exhibits gamma-radiation resistance approaching that of Deinococcus radiodurans. The genome was sequenced by the U.S. Department of Energy's Joint Genome Institute which suggested the existence of three replicons, a 4.76 Mb linear chromosome, a 0.18 Mb linear plasmid, and a 12.92 Kb circular plasmid. Southern hybridization confirmed that the chromosome is linear. The K. radiotolerans genome sequence was examined to learn about the physiology of the organism with regard to ionizing radiation resistance, the potential for bioremediation of nuclear waste, and the dimorphic life cycle. K. radiotolerans may have a unique genetic toolbox for radiation protection as it lacks many of the genes known to confer radiation resistance in D. radiodurans. Additionally, genes involved in the detoxification of reactive oxygen species and the excision repair pathway are overrepresented. K. radiotolerans appears to lack degradation pathways for pervasive soil and groundwater pollutants. However, it can respire on two organic acids found in SRS high-level nuclear waste, formate and oxalate, which promote the survival of cells during prolonged periods of starvation. The dimorphic life cycle involves the production of motile zoospores. The flagellar biosynthesis genes are located on a motility island, though its regulation could not be fully discerned. These results highlight the remarkable ability of K radiotolerans to withstand environmental extremes and suggest that in situ bioremediation of organic complexants from high level radioactive waste may be feasible.

Basal DNA repair machinery is subject to positive selection in ionizing-radiation-resistant bacteria.

BACKGROUND: Ionizing-radiation-resistant bacteria (IRRB) show a surprising capacity for adaptation to ionizing radiation and desiccation. Positive Darwinian selection is expected to play an important role in this trait, but no data are currently available regarding the role of positive adaptive selection in resistance to ionizing-radiation and tolerance of desiccation. We analyzed the four known genome sequences of IRRB (Deinococcus geothermalis, Deinococcus radiodurans, Kineococcus radiotolerans, and Rubrobacter xylanophilus) to determine the role of positive Darwinian selection in the evolution of resistance to ionizing radiation and tolerance of desiccation. RESULTS: We used the programs MultiParanoid and DnaSP to deduce the sets of orthologs that potentially evolved due to positive Darwinian selection in IRRB. We find that positive selection targets 689 ortholog sets of IRRB. Among these, 58 ortholog sets are absent in ionizing-radiation-sensitive bacteria (IRSB: Escherichia coli and Thermus thermophilus). The most striking finding is that all basal DNA repair genes in IRRB, unlike many of their orthologs in IRSB, are subject to positive selection. CONCLUSION: Our results provide the first in silico prediction of positively selected genes with potential roles in the molecular basis of resistance to gamma-radiation and tolerance of desiccation in IRRB. Identification of these genes provides a basis for future experimental work aimed at understanding the metabolic networks in which they participate.

Intracellular copper accumulation enhances the growth of Kineococcus radiotolerans during chronic irradiation.

The actinobacterium Kineococcus radiotolerans is highly resistant to ionizing radiation, desiccation, and oxidative stress, though the underlying biochemical mechanisms are unknown. The purpose of this study was to explore a possible linkage between the uptake of transition metals and extreme resistance to ionizing radiation and oxidative stress. The effects of six different divalent cationic metals on growth were examined in the absence of ionizing radiation. None of the metals tested were stimulatory, though cobalt was inhibitory to growth. In contrast, copper supplementation dramatically increased colony formation during chronic irradiation. K. radiotolerans exhibited specific uptake and intracellular accumulation of copper, compared to only a weak response to both iron and manganese supplementation. Copper accumulation sensitized cells to hydrogen peroxide. Acute-irradiation-induced DNA damage levels were similar in the copper-loaded culture and the age-synchronized no-copper control culture, though low-molecular-weight DNA was more persistent during postirradiation recovery in the Cu-loaded culture. Still, the estimated times for genome restoration differed by only 2 h between treatments. While we cannot discount the possibility that copper fulfills an unexpectedly important biochemical role in a low-radioactivity environment, K. radiotolerans has a high capacity for intracellular copper sequestration and presumably efficiently coordinated oxidative stress defenses and detoxification systems, which confers cross-protection from the damaging effects of ionizing radiation.

Effects of Ultraviolet Radiation on the Gram-positive marine bacterium Microbacterium maritypicum.

Although extensive information is available on the effect ultraviolet (UV) radiation has on Gram-negative marine bacteria, there is a scarcity of data concerning UV radiation and Gram-positive marine bacteria. The focus of this paper is on Microbacterium maritypicum, with the Gram-negative Vibrio natriegens being used as a standard of comparison. M. maritypicum exhibited growth over a NaCl range of 0-1000 mM: , with optimum growth occurring between 0 and 400 mM: NaCl. In contrast, V. natriegens grew over a NaCl span of 250-1000 mM: , with best growth being observed between 250 and 600 mM: NaCl. UV radiation experiments were done using the medium with 250 mM: NaCl. For solar (UV-A and B) radiation and log-phase cells, M. maritypicum was determined to be three times more resistant than V. natriegens. For germicidal (UV-C) radiation, the pattern of resistance of the log-phase cells to the lethal effects of the radiation was even more pronounced, with the Gram-positive bacterium being more than 12 to 13 times more resistant. Similar data to the solar and germicidal log-phase UV kill curves were obtained for stationary-phase cells of both organisms. Photoreactivation was observed for both types of cells exposed to UV-C but none for cells treated with UV-A and B. When log phase cells of M.maritypicum were grown at 0.0 and 0.6 M: NaCl and exposed to UV-C radiation, no difference in survivorship patterns was noted from that of 0.25 M: NaCl grown cells. Although this study has only focused on two marine bacteria, our results indicate that the Gram-positive M. maritypicum could have a built-in advantage for survival in some marine ecosystems.

Viability of fungal and actinomycetal spores after microwave radiation of building materials.

The effects of microwave radiation on viability of fungal and actinomycetal spores growing on agar (medium optimal for growth) as well as on wooden panel and drywall (common building construction/finishing materials) were studied. All materials were incubated at high (97-99%) and low (32-33%) relative humidity to mimic "wet" and "dry" environmental conditions. Two microwave power densities (10 and 60 mW/cm2) and three times of exposure (5, 30, and 60 min) were tested to find the most effective parameters of radiation which could be applied to non-invasive reduction or cleaning of building materials from microbial contaminants. Additionally, a control of the surface temperature during the experiments allowed differentiation between thermal and microwave effect of such radiation. The results showed that the viability of studied microorganisms differed depending on their strains, growth conditions, power density of microwave radiation, time of exposure, and varied according to the applied combination of the two latter elements. The effect of radiation resulting in a decrease of spore viability on "wet" wooden panel and drywall was generally observed at 60 min exposure. Shorter exposure times decreased the viability of fungal spores only, while in actinomycetes colonizing the studied building materials, such radiation caused an opposite (supporting growth) effect.

The role of pigmentation, ultraviolet radiation tolerance, and leaf colonization strategies in the epiphytic survival of phyllosphere bacteria.

Phenotypic mechanisms that enhance bacterial UVR survival typically include pigmentation and DNA repair mechanisms which provide protection from UVA and UVB wavelengths, respectively. In this study, we examined the contribution of pigmentation to field survival in Clavibacter michiganensis and evaluated differences in population dynamics and leaf colonization strategies. Two C. michiganensis pigment-deficient mutants were significantly reduced in UVA radiation survival in vitro; one of these mutants also exhibited reduced field populations on peanut when compared to the wild-type strain over the course of replicate 25-day experiments. The UVR-tolerant C. michiganensis strains G7.1 and G11.1 maintained larger epiphytic field populations on peanut compared to the UVR-sensitive C. michiganensis T5.1. Epiphytic field populations of C. michiganensis utilized the strategy of solar UVR avoidance during leaf colonization resulting in increased strain survival on leaves after UVC irradiation. These results further demonstrate the importance of UVR tolerance in the ability of bacterial strains to maintain population size in the phyllosphere. However, an examination of several bacterial species from the peanut phyllosphere and a collection of environmental Pseudomonas spp. revealed that sensitivity to UVA and UVC radiation was correlated in some but not all of these bacteria. These results underscore a need to further understand the biological effects of different solar wavelength groups on microbial ecology.

Kineococcus radiotolerans sp. nov., a radiation-resistant, gram-positive bacterium.

A gram-type positive, motile, coccus-shaped organism was isolated from a radioactive work area. Strain SRS30216T is an orange-pigmented bacterium that is catalase-positive, oxidase-negative and urease-negative. The orange pigment is most likely a carotenoid with absorption peaks at approximately 444, 471 and 501 nm. Cells normally grew in clusters, but individual, motile, flagellated cells were also observed. Growth of strain SRS30216T occurred at temperatures between 11 and 41 degrees C, between pH 5 and 9 and at NaCl concentrations up to and including 5%. Fatty acid composition was limited, with >90% of the fatty acids being anteiso 15:0. Alkenes of 19-24 carbons in length were detected during examination of the neutral lipids. Strain SRS30216T demonstrated high levels of resistance to gamma-radiation and desiccation. The most closely related recognized species is Kineococcus aurantiacus RA 333T, which is 93% similar in 16S rDNA sequence. DNA-DNA hybridization revealed only 31% similarity between these two organisms. It is proposed that SRS30216T (= ATCC BAA-149T = DSM 14245T) represents the type strain of a novel species in the genus Kineococcus, Kineococcus radiotolerans sp. nov..

[Increase in eremomycin production by regeneration and UV-irradiation of Amycolatopsis orientalis subsp. eremomycini protoplasts]. / Uvelichenie produktsii éremomitsina v rezul'tate regeneratsii i UF-oblucheniia protoplastov Amycolatopsis orientalis subsp. eremomycini.

Protoplast regeneration of Amycolatopsis orientalis subsp. eremomycini producing eremomycin leads to the change of cultural and morphological properties as well as synthesis of secondary metabolites. Formation of plus-variants with enchanced antibiotic production was promoted by UV-irradiation of protoplasts. These plus-variants can be successfully used for repeating protoplasting--UV-irradiation of protoplasts with further increasing of the strain productivity. Finally activity of the initial A. orientalis culture was increased 7-8 times. Proposed method is recommended for the improvement of actinomycetes strains producing antibiotics especially in the case of cultures with poor sporulation.