Histopathology of the Shoot Apex of Sugarcane Colonized by Leifsonia xyli subsp. xyli.

Colonization of the xylem of sugarcane by Leifsonia xyli subsp. xyli results in the occlusion of the vessels by a gum-like compound and compromises the elongation of the stalk leading to stunted plants. However, no study has been performed in the apical tissue where the elongation of the stalks initiates at the intercalary meristem (IM). Microscopic and histochemical analyses were performed in plants with lower and higher bacterial titers and revealed that in both cases L. xyli subsp. xyli is present in this tissue and colonizes the forming xylem vessels in a similar way as observed in developed internodes. In both cases, it was observed adhering to the secondary walls, but only in plants with higher titers were a mild degradation of the walls and a granular material filling the vessels observed. The mixed composition of lipids, proteins, and pectin indicates that the filling is not a bacterial extracellular polymeric substance. Plants with higher bacterial populations also presented lower starch content in the ground parenchyma at the node elements, possibly resulting from the reported downregulation of photosynthesis and increased accumulation of phenolics. Their second and third IMs presented fewer cells and reduced expression of genes related to the cell cycle and to the synthesis of ABA in the apical tissue. These results indicate that increased L. xyli subsp. xyli colonization affects the development of the IM, which ultimately would reduce the length of the internodes, resulting in the main symptom of the disease.

Glaciibacter flavus sp. nov., isolated from a lichen sample.

A novel Actinobacterium strain YIM 131861 T, was isolated from lichen collected from the South Bank Forest of the Baltic Sea, Germany. It was Gram-stain-positive, strictly aerobic, catalase positive and oxidase negative, yellow pigmented. Cells were motile with a polar flagellum, irregular rod shaped and did not display spore formation. The strain grew at 15 - 30 °C (optimum 25 °C), at pH 6.0 - 10.0 (optimum pH 7.0) and in the presence of 0 - 1.5% (w/v) NaCl (optimum 1%). Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain YIM 131861 T belonged to the genus Glaciibacter, and exhibited a high sequence similarity (96.4%) with Glaciibacter superstes NBRC 104264 T. The genomic DNA G + C content of strain YIM 131861 T was 68.2 mol%. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between strain YIM 131861 T and Glaciibacter superstes NBRC 104264 T were 73.2 and 19.9% based on the draft genome sequence. The cell-wall peptidoglycan type was B2γ and contained the 2, 4-diaminobutyric acid as the diagnostic amino acid. Whole cell sugars were galactose, rhamnose, ribose and glucose. It contained MK-12 and MK-13 as the predominant menaquinones. The major cellular fatty acids (> 10%) were identified as anteiso-C15:0, iso-C16:0 and anteiso-C17:0. The polar lipids were diphosphatidylglycerol, phosphatidylglycerol and two unknown glycolipids. Based on the results of phenotypic, chemotaxonomic and phylogenetic analyses, strain YIM 131861 T should belong to the genus Glaciibacter and represents a novel species of the genus Glaciibacter, for which the name Glaciibacter flavus sp. nov. is proposed. The type strain is YIM 131861 T (= CGMCC 1.16588 T = NBRC 113572 T).

Agromyces laixinhei sp. nov. isolated from bat feces in China.

Three rod-shaped, Gram-stain-positive, and catalase-positive, phenotypically closely related isolates (HY052T, HY050, and HY045) were obtained from fecal samples collected from bats in Guangxi province and Chongqing city of China. Circular, smooth, light-yellow colonies appeared on brain heart infusion plate after 24-48 h incubation at 28°C. The optimal pH for growth was between 6.0 and 7.5. Based on 16S rRNA, the three isolates were phylogenetically related to Agromyces terreus DS-10T, Agromyces aureus AR33T, Agromyces salentinus 20-5T, Agromyces allii UMS-62T, Agromyces lapidis CD55T, and Agromyces italicus CD1T. Moreover, based on 296 core genes, the phylogenomic tree indicated that the three isolates clustered together, closest to Agromyces cerinus VKM Ac-1340T and Agromyces fucosus VKM Ac-1345T but separated distantly from other Agromyces species. The average nucleotide identity values between strain HY052T and other Agromyces species ranged from 79.3% to 87.9%, lower than the 95-96% threshold. Furthermore, the genome of strain HY052T contains a circular chromosome of 3,437,203 bp with G + C content of 69.0 mol%. Main fatty acids were anteiso-C15:0 and anteiso-C17:0. The polar lipids comprised diphosphatidylglycerol, phosphatidylglycerol, and unidentified glycolipids. Rhamnose, ribose, and glucose were the primary cell wall sugars. The major peptidoglycan amino acids included alanine, glutamic acid, glycine, and 2,4-diaminobutyric acid. An additional remarkable difference from other Agromyces species is that MK-12 was the sole menaquinone in strain HY052T. Based on results from the polyphasic characterizations performed in this study, our isolates are proposed to be members of a novel species in genus Agromyces, named Agromyces laixinhei. The type strain is HY052T (= CGMCC 1.17175T = JCM 33695T).

Zinc- and cadmium-tolerant endophytic bacteria from Murdannia spectabilis (Kurz) Faden. studied for plant growth-promoting properties, in vitro inoculation, and antagonism.

This research aims to isolate and identify Zn- and Cd-tolerant endophytic bacteria from Murdannia spectabilis, identify their properties with and without Zn and Cd stress, and to investigate the effect of bacterial inoculation in an in vitro system. Twenty-four isolates could survive on trypticase soya agar (TSA) supplemented with Zn (250-500 mg L-1) and/or Cd (20-50 mg L-1) that belonged to the genera Bacillus, Pantoea, Microbacterium, Curtobacterium, Chryseobacterium, Cupriavidus, Siphonobacter, and Pseudomonas. Each strain had different indole-3-acetic acid (IAA), 1-aminocyclopropane-1-carboxylate (ACC) deaminase and siderophore production, nitrogen fixation, phosphate solubilization, and lignocellulosic enzyme characteristics. Cupriavidus plantarum MDR5 and Chryseobacterium sp. MDR7 were selected for inoculation into plantlets that were already occupied by Curtobacterium sp. TMIL due to them have a high tolerance for Zn and Cd while showing no pathogenicity. As determined via an in vitro system, Cupriavidus plantarum MDR5 remained in the plants to a greater extent than Chryseobacterium sp. MDR7, while Curtobacterium sp. TMIL was the dominant species. The Zn plus Cd treatment supported the persistence of Cupriavidus plantarum MDR5. Dual and mixed cultivation showed no antagonistic effects between the endophytes. Although the plant growth and Zn/Cd accumulation were not significantly affected by the Zn-/Cd-tolerant endophytes, the inoculation did not weaken the plants. Therefore, Cupriavidus plantarum MDR5 could be applied in a bioaugmentation process.

Morphological and physiological characterization of filamentous Lentzea aerocolonigenes: Comparison of biopellets by microscopy and flow cytometry.

Cell morphology of filamentous microorganisms is highly interesting during cultivations as it is often linked to productivity and can be influenced by process conditions. Hence, the characterization of cell morphology is of major importance to improve the understanding of industrial processes with filamentous microorganisms. For this purpose, reliable and robust methods are necessary. In this study, pellet morphology and physiology of the rebeccamycin producing filamentous actinomycete Lentzea aerocolonigenes were investigated by microscopy and flow cytometry. Both methods were compared regarding their applicability. To achieve different morphologies, a cultivation with glass bead addition (Ø = 969 µm, 100 g L-1) was compared to an unsupplemented cultivation. This led to two different macro-morphologies. Furthermore, glass bead addition increased rebeccamycin titers after 10 days of cultivation (95 mg L-1 with glass beads, 38 mg L-1 without glass beads). Macro-morphology and viability were investigated through microscopy and flow cytometry. For viability assessment fluorescent staining was used additionally. Smaller, more regular pellets were found for glass bead addition. Pellet diameters resulting from microscopy followed by image analysis were 172 µm without and 106 µm with glass beads, diameters from flow cytometry were 170 and 100 µm, respectively. These results show excellent agreement of both methods, each considering several thousand pellets. Furthermore, the pellet viability obtained from both methods suggested an enhanced metabolic activity in glass bead treated pellets during the exponential production phase. However, total viability values differ for flow cytometry (0.32 without and 0.41 with glass beads) and confocal laser scanning microscopy of single stained pellet slices (life ratio in production phase of 0.10 without and 0.22 with glass beads), which is probably caused by the different numbers of investigated pellets. In confocal laser scanning microscopy only one pellet per sample could be investigated while flow cytometry considered at least 50 pellets per sample, resulting in an increased statistical reliability.

Phenotypic divergence of thermotolerance: Molecular basis and cold adaptive evolution related to intrinsic DNA flexibility of glacier-inhabiting Cryobacterium strains.

The link between guanine-cytosine (GC) content and thermal adaptation is controversial. Here, we compared maximum growth temperature (TMGT ) and genomics of 78 Cryobacterium strains to avoid unreliable conclusions resulting from distantly phylogenetic groups. Phylogenomic analysis revealed this taxon had much higher diversification than we knew. Interestingly, these strains showed thermotolerance divergence with phylogenetic cohesion. A significant difference was found between TMGT ≤ 20°C strains and TMGT > 20°C strains in genomic GC content which mainly caused by variation of GC3. TMGT ≤ 20°C strains tended to use synonymous codons ended with A/U, but TMGT > 20°C strains tended to use G/C. Lower GC content at synonymous sites (≈GC3) of TMGT ≤ 20°C strains could provide lower intrinsic DNA flexibility which strongly associated with optimal molecular dynamics, and then guarantee DNA function at lower growth temperatures. This analysis of codon bias revealed close relationships for thermal adaptation, GC content at synonymous sites (≈GC3), intrinsic DNA flexibility and optimal DNA dynamics. Natural selection was main force driving this codon bias; strains with lower TMGT endured stronger natural selection. Therefore, this study provided molecular basis for bacterial adaptive evolution from moderate temperature to low temperature.

Activities of key enzymes in the C4 pathway and anatomy of sugarcane infected by Leifsonia xyli subsp. xyli.

AIMS: Ratoon stunting disease caused by Leifsonia xyli subsp. xyli (Lxx) is a bacterial disease that has plagued sugarcane-planting countries for a long time. This study mainly analysed Lxx localization and its effects on sugarcane leaf. METHODS AND RESULTS: Badila were inocultated by bacteria of Lxx. It was noted that the number of Lxx cells were rapidly enriched in sugarcane leaves from the 150th to the 210th days of post inoculation (dpi). Lxx infection disrupted the integrity of vascular bundle sheath cells (BSC) in the 'Kranz anatomy' of leaves, resulting in irregular accumulation of starch in vascular BSC of leaves. In situ PCR showed that the Lxx localized in the xylem vessels, mesophyll cell (MC) and BSC as described before in sugarcane leaf, a new niche within the host tissues in the phloem of sugarcane stem. The gene expression and activities of phosphoenolpyruvate carboxylase (PEPC), pyruvate, orthophosphate dikinase (PPDK) and NADP-malic enzyme (NADP-ME) enzymes were lower in Lxx-inoculated sugarcane plants as compared to the MI group. CONCLUSION: Lxx infection not only disrupted the structure of vascular BSC in the C4 'Kranz anatomy' of sugarcane leaves, but also affected the activities and gene expression of the key enzymes PEPC, PPDK and NADP-ME in the C4 cycle of sugarcane suggesting a reduction in CO2 fixation. SIGNIFICANCE AND IMPACT OF THE STUDY: The effect of Leifsonia xyli subsp. xyli (Lxx) infection on the photosynthetic physiology of sugarcane is currently limited to the evaluation of photosynthetic parameters. This study assessed the impact of Lxx infection on the mechanism of C4 cycle CO2 fixation and to accompanying plant anatomy.

New Caledonian ultramafic conditions structure the features of Curtobacterium citreum strains that play a role in plant adaptation.

The present study focused on the characterization of 10 Curtobacterium citreum strains isolated from the rhizosphere of pioneer plants growing on ultramafic soils from New Caledonia. Taxonomic status was investigated using a polyphasic approach. Three strains (BE, BB, and AM) were selected in terms of multiple-metal resistance and plant-growth-promoting traits. They were tested on sorghum growing on ultramafic soil and compared with the reference strain C. citreum DSM20528T. To better understand the bacterial mechanisms involved, biosorption, bioaccumulation, and biofilm formation were investigated for the representative strain of the ultramafic cluster (strain BE) versus C. citreum DSM20528T. The polyphasic approach confirmed that all native isolates belong to the same cluster and are C. citreum. The inoculation of sorghum with strains BE and BB significantly reduced Ni content in shoots compared with inoculation with C. citreum DSM20528T and control values. This result was related to the higher Ni tolerance of the ultramafic strains compared with C. citreum DSM20528T. Ni biosorption and bioaccumulation showed that BE exhibited a lower Ni content, which is explained by the ability of this strain to produce exopolysaccharides involved in Ni chelation. We suggested that ultramafic C. citreum strains are more adapted to this substrate than is C. citreum DSM20528T, and their features allow them to enhance plant metal tolerance.

Rhizospheric Microbacterium sp. P27 Showing Potential of Lindane Degradation and Plant Growth Promoting Traits.

Lindane is an organochlorine pesticide that is highly persistent in the environment. The amassing of lindane has been identified worldwide and has been found to be very toxic to the environment, human, and animal health. Therefore, urgent consideration and management of the problem is necessary. The current study intends to isolate and identify lindane degrading rhizospheric bacteria from Phragmites karka and to study its degradation kinetics. Also, plant growth promoting potential of the bacterium was evaluated in the presence and absence of studied pesticide. Rhizospheric bacteria were isolated by standard enrichment technique in Mineral Salt Medium. Microbacterium sp. P27 showed the highest degradation percentage, 82.7 ± 1.79% for 50 mg l-1 lindane, after 15 days. Degradation was also studied at different concentrations of lindane. Maximum degradation was achieved at 10 mg l-1 followed by 50 mg l-1 and 100 mg l-1 lindane. Microbacterium sp. P27 showed positive result for Indole-3-acetic acid production, ammonia production, and 1-aminocyclopropane-1-carboxylate deaminase activity. Presence of lindane revealed a concentration-dependent decrease in plant growth promoting activity. Since the isolated bacterial strain possesses lindane degrading capacity and also other characters that help in plant growth promotion, the isolate can be an important candidate for the progress of bioremediation strategy.

Transcriptome analysis of Valsa mali reveals its response mechanism to the biocontrol actinomycete Saccharothrix yanglingensis Hhs.015.

BACKGROUND: Apple canker is a devastating branch disease caused by Valsa mali (Vm). The endophytic actinomycete Saccharothrix yanglingensis Hhs.015 (Sy Hhs.015) can effectively inhibit the growth of Vm. To reveal the mechanism, by which Vm respond to Sy Hhs.015, the transcriptome of Vm was analyzed using RNA-seq technology. RESULTS: Compared with normal growing Vm in the control group, 1476 genes were significantly differentially expressed in the Sy Hhs.015's treatment group, of which 851 genes were up-regulated and 625 genes were down-regulated. Combined gene function and pathway analysis of differentially expressed genes (DEGs) revealed that Sy Hhs.015 affected the carbohydrate metabolic pathway, which is utilized by Vm for energy production. Approximately 82% of the glycoside hydrolase genes were down-regulated, including three pectinase genes (PGs), which are key pathogenic factors. The cell wall structure of Vm was disrupted by Sy Hhs.015 and cell wall-related genes were found to be down-regulated. Of the peroxisome associated genes, those encoding catalase (CAT) and superoxide dismutase (SOD) which scavenge reactive oxygen species (ROS), as well as those encoding AMACR and ACAA1 which are related to the ß-oxidation of fatty acids, were down-regulated. MS and ICL, key genes in glyoxylate cycle, were also down-regulated. In response to the stress of Sy Hhs.015 exposure, Vm increased amino acid metabolism to synthesize the required nitrogenous compounds, while alpha-keto acids, which involved in the TCA cycle, could be used to produce energy by deamination or transamination. Retinol dehydrogenase, associated with cell wall dextran synthesis, and sterol 24-C-methyltransferase, related to cell membrane ergosterol synthesis, were up-regulated. The genes encoding glutathione S-transferase, (GST), which has antioxidant activity and ABC transporters which have an efflux function, were also up-regulated. CONCLUSION: These results show that the response of Vm to Sy Hhs.015 exposure is a complicated and highly regulated process, and provide a theoretical basis for both clarifying the biocontrol mechanism of Sy Hhs.015 and the response of Vm to stress.

Novel Insights Into the Early Stages of Ratoon Stunting Disease of Sugarcane Inferred from Transcript and Protein Analysis.

Despite of the importance of ratoon stunting disease, little is known on the responses of sugarcane to its causal agent, the vascular bacterial endophyte Leifsonia xyli subsp. xyli. The transcriptome and proteome of young plants of a susceptible cultivar with no symptoms of stunting but with relative low and high bacterial titers were compared at 30 and 60 days after inoculation. Increased bacterial titers were associated with alterations in the expression of 267 cDNAs and in the abundance of 150 proteins involved in plant growth, hormone metabolism, signal transduction and defense responses. Some alterations are predicted to benefit the pathogen, such as the up-regulation of genes involved in the synthesis of methionine. Also, genes and proteins of the cell division cycle were all down-regulated in plants with higher titers at both times. It is hypothesized that the negative effects on cell division related to increased bacterial titers is cumulative over time and its modulation by other host and environmental factors results in the stunting symptom.

Neuronal and non-neuronal signals regulate Caernorhabditis elegans avoidance of contaminated food.

One way in which animals minimize the risk of infection is to reduce their contact with contaminated food. Here, we establish a model of pathogen-contaminated food avoidance using the nematode worm Caernorhabditis elegans We find that avoidance of pathogen-contaminated food protects C. elegans from the deleterious effects of infection and, using genetic approaches, demonstrate that multiple sensory neurons are required for this avoidance behaviour. In addition, our results reveal that the avoidance of contaminated food requires bacterial adherence to non-neuronal cells in the tail of C. elegans that are also required for the cellular immune response. Previous studies in C. elegans have contributed significantly to our understanding of molecular and cellular basis of host-pathogen interactions and our model provides a unique opportunity to gain basic insights into how animals avoid contaminated food.This article is part of the Theo Murphy meeting issue 'Evolution of pathogen and parasite avoidance behaviours'.

Turning a Blind Eye to Ratoon Stunting Disease of Sugarcane in Australia.

The Australian sugar industry has never pursued genetic resistance to ratoon stunting disease (RSD), despite it being widely considered to be one of the most important diseases of sugarcane (Saccharum interspecific hybrids). This is because of a prevailing view that the disease is economically managed, and that no further action needs to take place. However, there is a range of epidemiological evidence that suggests that RSD is having a more significant impact than what is generally recognized. This review traces the factors that have led to an industry stance that is apparently without any scientific justification, and which has tended to downplay the significance of RSD on Australian sugarcane productivity, and thus has led to significant lost production. The consequences of this position are that RSD may be influencing broad but poorly explained issues such as commercial ratooning performance of existing varieties and the "yield decline" that has been subject to much scrutiny, if not much success in resolving the issue. Based on the available information, this review calls on the Australian sugar industry to prioritize selection for RSD resistance in the plant improvement program.

Subtercola vilae sp. nov., a novel actinobacterium from an extremely high-altitude cold volcano lake in Chile.

A novel actinobacterium, strain DB165T, was isolated from cold waters of Llullaillaco Volcano Lake (6170 m asl) in Chile. Phylogenetic analysis based on 16S rRNA gene sequences identified strain DB165T as belonging to the genus Subtercola in the family Microbacteriaceae, sharing 97.4% of sequence similarity with Subtercola frigoramans DSM 13057T, 96.7% with Subtercola lobariae DSM 103962T, and 96.1% with Subtercola boreus DSM 13056T. The cells were observed to be Gram-positive, form rods with irregular morphology, and to grow best at 10-15 °C, pH 7 and in the absence of NaCl. The cross-linkage between the amino acids in its peptidoglycan is type B2γ; 2,4-diaminobutyric acid is the diagnostic diamino acid; the major respiratory quinones are MK-9 and MK-10; and the polar lipids consist of phosphatidylglycerol, diphosphatidylglycerol, 5 glycolipids, 2 phospholipids and 5 additional polar lipids. The fatty acid profile of DB165T (5% >) contains iso-C14:0, iso-C16:0, anteiso-C15:0, anteiso-C17:0, and the dimethylacetal iso-C16:0 DMA. The genomic DNA G+C content of strain DB165T was determined to be 65 mol%. Based on the phylogenetic, phenotypic, and chemotaxonomic analyses presented in this study, strain DB165T (= DSM 105013T = JCM 32044T) represents a new species in the genus Subtercola, for which the name Subtercola vilae sp. nov. is proposed.

Kribbella podocarpi sp. nov., isolated from the leaves of a yellowwood tree (Podocarpus latifolius).

An endophytic actinobacterial strain was isolated from a yellowwood tree growing on the slope of Devil's Peak, Cape Town, South Africa. Analysis of the 16S rRNA gene showed that the strain belongs to the genus Kribbella. Phylogenetic analyses using the 16S rRNA gene and multilocus sequence analysis using the concatenated gene sequences of the gyrB, rpoB, relA, recA and atpD genes showed that strain YPL1T is closely related to the type strains of Kribbella karoonensis and Kribbella shirazensis. DDH experiments showed that strain YPL1T is a distinct genomic species from its close phylogenetic relative, K. karoonensis Q41T. Physiological comparisons further showed that strain YPL1T is phenotypically distinct from the type strains of Kribbella jejuensis, Kribbella aluminosa, K. karoonensis, K. shirazensis and Kribbella swartbergensis. Strain YPL1T is thus presented as the type strain of a novel species, for which the name Kribbella podocarpi sp. nov. (= DSM 29424T = NRRL B-65063T), is proposed.

Isolation, biochemical and molecular identification of Nocardia species among TB suspects in northeastern, Tanzania; a forgotten or neglected threat?

BACKGROUND: Pulmonary nocardiosis mimic pulmonary tuberculosis in most clinical and radiological manifestations. In Tanzania, where tuberculosis is one of the major public health threat clinical impact of nocardiosis as the cause of the human disease remains unknown. The objective of the present study was to isolate and identify Nocardia isolates recovered from TB suspects in Northeastern, Tanzania by using biochemical and molecular methods. METHODS: The study involved 744 sputum samples collected from 372 TB suspects from four periphery diagnostic centers in Northeastern, Tanzania. Twenty patients were diagnosed as having presumptively Nocardia infections based on microscopic, cultural characteristics and biomèrieux ID 32C Yeast Identification system and confirmed using 16S rRNA and hsp65 gene specific primers for Nocardia species and sequencing. RESULTS: Biochemically, the majority of the isolates were N. asteroides (n = 8/20, 40%), N. brasiliensis (n = 4/20, 20%), N. farcinica (n = 3/20, 15%), N. nova (n = 1/20, 5%). Other aerobic actinomycetales included Streptomyces cyanescens (n = 2/20, 10%), Streptomyces griseus, Actinomadura madurae each (n = 1/20, 5%). Results of 16S rRNA and hsp65 sequencing were concordant in 15/17 (88. 2%) isolates and discordant in 2/17 (11.8%) isolates. Majority of the isolates belonged to N. cyriacigeorgica and N. farcinica, four (23.5%) each. CONCLUSIONS: Our findings suggest that Nocardia species may be an important cause of pulmonary nocardiosis that is underdiagnosed or ignored. This underscores needs to consider pulmonary nocardiosis as a differential diagnosis when there is a failure of anti-TB therapy and as a possible cause of human infections.

Molecular Detection of Diverse Leifsonia Strains Associated With Sugarcane.

Leifsonia xyli subsp. xyli, causal agent of ratoon stunting disease (RSD) of sugarcane (Saccharum interspecific hybrids), is the most well-known member of the Microbacteriaceae genus Leifsonia. However, the presence of other Leifsonia strains associated with sugarcane has not been reported. A total of 697 Australian and 40 Indonesian sugarcane fields were screened by leaf sheath biopsy (LSB) PCR using primers specific for L. xyli subsp. xyli, in addition to primers designed to amplify DNA from other members of the genus Leifsonia. While L. xyli subsp. xyli was detected in 126 fields, a total of 37 distinct and novel Leifsonia and non-Leifsonia strains were detected in 116 fields. Representatives of these strains were also detected in multiple samples of expressed xylem sap. Sequencing and phylogenetic analyses demonstrated the presence of a broad complex of novel Leifsonia strains, in addition to strains closely related to the recently erected Cnuibacter genus. Attempts to isolate Leifsonia strains were unsuccessful; however, one strain related to Cnuibacter was recovered from expressed xylem sap. Among the genetically diverse lineages discovered, identical genotypes were present in multiple sugarcane varieties growing in disparate regions in different years, strongly suggesting an ongoing association with sugarcane. The epidemiological significance of these strains is unknown, but there is evidence that they can interfere with serological and microscopic RSD diagnostics, and there is the potential that they may represent new and distinct pathologies of sugarcane.

The complete genome of Dietzia timorensis ID05-A0528T revealed the genetic basis for its saline-alkali tolerance.

The type strain Dietzia timorensis ID05-A0528T, was reported to be able to survive in the highly saline and alkaline environments with diverse carbon sources. In order to more pertinently understand the genetic mechanisms of its environmental tolerance and crude oil emulsification, we reported the complete genome sequence of the strain in the study. The genome contains only one circular chromosome, with the total size of 3,607,892 bps, and the G+C content of this strain is 65.58%, much lower than other type strains of this genus. It was found that strain ID05-A0528T contains genes involved in transportation and biosynthesis of compatible solutes, as well as genes encoding monovalent cation/proton antiporters, which could explain its abilities to tolerate high salinity and alkalinity. Various central metabolic routes and complete alkane hydroxylation pathway were also identified in the genome of strain ID05-A0528T, which is in accordance with its ability to use a wide spectrum of carbon sources and to degrade n-alkanes.

Blastococcus colisei sp. nov, isolated from an archaeological amphitheatre.

The taxonomic position of an actinobacterial isolate, designated strain BMG 822T, isolated from limestone from the Amphitheater of El Jem (Coliseum Thysdrus), Tunisia, was established using a polyphasic approach. Strain BMG 822T was found to grow well at 30 °C and pH 6.5-8.0, and to be coral-coloured, Gram-positive, catalase and oxidase negative. Whole cell hydrolysates contained meso-diaminopimelic acid as the diagnostic diamino acid, glucose, galactose and ribose. The phospholipids detected were diphosphatidylglycerol, phosphatidylcholine, phosphatidylinositol, phosphatidylethanolamine, hydroxy-phosphatidylethanolamine, an unidentified glycophospholipid and six unidentified phospholipids. MK-9(H4) was found to be the predominant menaquinone, followed by MK-9(H2) and MK-9. The major cellular fatty acids were identified as iso-C16:0, C18:1 ω9c, C17:1 ω8c and iso-H-C16:1. The G+C content of the DNA (73.2%) is typical of the genus. High degrees of 16S rRNA gene sequence similarity were found with the type strains of the genus Blastococcus (97.1-98.3%) followed by the type strains of Modestobacter (96.8-97.8%). Based on the above data and the phenotypic differences from the type strains of Blastococcus species, it is proposed that the isolate BMG 822T (=DSM 46837T=CECT 8823T) should be classified as the type strain of a novel species, Blastococcus colisei sp. nov.

Saccharothrix ghardaiensis sp. nov., an actinobacterium isolated from Saharan soil.

The taxonomic position of a new Saccharothrix strain, designated MB46T, isolated from a Saharan soil sample collected in Mzab region (Ghardaïa province, South Algeria) was established following a polyphasic approach. The novel microorganism has morphological and chemical characteristics typical of the members of the genus Saccharothrix and formed a phyletic line at the periphery of the Saccharothrix espanaensis subcluster in the 16S rRNA gene dendrograms. Results of the 16S rRNA gene sequence comparisons revealed that strain MB46T shares high degrees of similarity with S. espanaensis DSM 44229T (99.2%), Saccharothrix variisporea DSM 43911T (98.7%) and Saccharothrix texasensis NRRL B-16134T (98.6%). However, the new strain exhibited only 12.5-17.5% DNA relatedness to the neighbouring Saccharothrix spp. On the basis of phenotypic characteristics, 16S rRNA gene sequence comparisons and DNA-DNA hybridizations, strain MB46T is concluded to represent a novel species of the genus Saccharothrix, for which the name Saccharothrix ghardaiensis sp. nov. (type strain MB46T = DSM 46886T = CECT 9046T) is proposed.