In vitro activity of bedaquiline against rapidly growing nontuberculous mycobacteria

Bedaquiline (BDQ) has been proven to be effective in the treatment of multidrug-resistant tuberculosis. We hypothesized that BDQ could be a potential agent to treat nontuberculous mycobacterial (NTM) infection. The objective of this study was to evaluate the in vitro activity of BDQ against rapidly growing mycobacteria by assessing the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) against 18 NTM strains. For MIC determination we performed the resazurin microtitre assay broth dilution, and for the MBC the c.f.u. was determined. BDQ exhibited a strong inhibitory effect against most NTM tested; however, for some NTM strains the MBC was significantly higher than the MIC. A new finding is that Mycobacterium flavescens has a mutation in the gene atpE associated with natural resistance to BDQ. These preliminary promising results demonstrate that BDQ could be potentially useful for the treatment of NTM

Dysbiosis of the faecal microbiota in patients with Crohn's disease and their unaffected relatives

Background and aims A general dysbiosis of the intestinal microbiota has been established in patients with Crohn's disease (CD), but a systematic characterisation of this dysbiosis is lacking. Therefore the composition of the predominant faecal microbiota of patients with CD was studied in comparison with the predominant composition in unaffected controls. Whether dysbiosis is present in relatives of patients CD was also examined. Methods Focusing on families with at least three members affected with CD, faecal samples of 68 patients with CD, 84 of their unaffected relatives and 55 matched controls were subjected to community fingerprinting of the predominant microbiota using denaturing gradient gel electrophoresis (DGGE). To analyse the DGGE profiles, BioNumerics software and non-parametric statistical analyses (SPSS V. 17.0) were used. Observed differences in the predominant microbiota were subsequently confirmed and quantified with real-time PCR. Results Five bacterial species characterised dysbiosis in CD, namely a decrease in Dialister invisus (p = 0.04), an uncharacterised species of Clostridium cluster XIVa (p = 0.03), Faecalibacterium prausnitzii (p<1.3x10(-5)) and Bifidobacterium adolescentis (p = 5.4x10(-6)), and an increase in Ruminococcus gnavus (p = 2.1x10(-7)). Unaffected relatives of patients with CD had less Collinsella aerofaciens (p = 0.004) and a member of the Escherichia coli-Shigella group (p = 0.01) and more Ruminococcus torques (p = 0.02) in their predominant microbiota as compared with healthy subjects. Conclusion Unaffected relatives of patients with CD have a different composition of their microbiota compared with healthy controls. This dysbiosis is not characterised by lack of butyrate producing-bacteria as observed in CD but suggests a role for microorganisms with mucin degradation capacity

Caenibacterium thermophilum is a later synonym of Schlegelella thermodepolymerans

Recently, two strains of Schlegelella thermodepolymerans Elbanna et al. 2003 and an independently isolated bacterium, Caenibacterium thermophilum Manaia et al. 2003, were described in parallel as gen. nov., sp. nov. Analysis of the 16S rRNA genes revealed similarity between C. thermophilum and the two strains of S. thermodepolymerans of 99?8 and 99?6%, respectively. DNA–DNA hybridization experiments revealed mean DNA reassociation levels of 97–98% among C. thermophilum and the two strains of S. thermodepolymerans, thereby confirming the close relationship and indicating that C. thermophilum is a later synonym of S. thermodepolymerans.info:eu-repo/semantics/publishedVersio

Introducing SPeDE : high-throughput dereplication and accurate determination of microbial diversity from matrix-assisted laser desorption-ionization time of flight mass spectrometry data

The isolation of microorganisms from microbial community samples often yields a large number of conspecific isolates. Increasing the diversity covered by an isolate collection entails the implementation of methods and protocols to minimize the number of redundant isolates. Matrix-assisted laser desorption-ionization time-of-flight (MALDI-TOF) mass spectrometry methods are ideally suited to this dereplication problem because of their low cost and high throughput. However, the available software tools are cumbersome and rely either on the prior development of reference databases or on global similarity analyses, which are inconvenient and offer low taxonomic resolution. We introduce SPeDE, a user-friendly spectral data analysis tool for the dereplication of MALDI-TOF mass spectra. Rather than relying on global similarity approaches to classify spectra, SPeDE determines the number of unique spectral features by a mix of global and local peak comparisons. This approach allows the identification of a set of nonredundant spectra linked to operational isolation units. We evaluated SPeDE on a data set of 5,228 spectra representing 167 bacterial strains belonging to 132 genera across six phyla and on a data set of 312 spectra of 78 strains measured before and after lyophilization and subculturing. SPeDE was able to dereplicate with high efficiency by identifying redundant spectra while retrieving reference spectra for all strains in a sample. SPeDE can identify distinguishing features between spectra, and its performance exceeds that of established methods in speed and precision. SPeDE is open source under the MIT license and is available from https://github.com/LM-UGent/SPeDE. IMPORTANCE Estimation of the operational isolation units present in a MALDI-TOF mass spectral data set involves an essential dereplication step to identify redundant spectra in a rapid manner and without sacrificing biological resolution. We describe SPeDE, a new algorithm which facilitates culture-dependent clinical or environmental studies. SPeDE enables the rapid analysis and dereplication of isolates, a critical feature when long-term storage of cultures is limited or not feasible. We show that SPeDE can efficiently identify sets of similar spectra at the level of the species or strain, exceeding the taxonomic resolution of other methods. The high-throughput capacity, speed, and low cost of MALDI-TOF mass spectrometry and SPeDE dereplication over traditional gene marker-based sequencing approaches should facilitate adoption of the culturomics approach to bacterial isolation campaigns

Optimization of culture conditions for gamma-aminobutyric acid production by newly identified Pediococcus pentosaceus MN12 isolated from 'mam nem', a fermented fish sauce

This study was aimed to identify and optimize the culture conditions for gamma-aminobutyric acid (GABA) production by a lactic acid bacterium strain isolated from mam nem, a fermented fish sauce. Among the six isolates obtained from mam nem, the MN12 had the most potent GABA-producing capability. The strain was then identified to be Pedioccocus pentosaceus by employing MALDI-TOF-MS and phenylalanyl-tRNA synthase sequencing methods. The initial cell density of 5.10(6) CFU/mL, monosodium glutamate concentration of 60 mM, initial pH of 7, temperature of 45 degrees C and cultivation time of 72 h were found to be the optimal culture conditions for highest production of GABA, reaching 27.9 +/- 0.42 mM, by this strain. The cultivation conditions for GABA production by P. pentosaceus MN12 have been successfully optimized, providing a foundation for the development of fermented foods enriched with GABA

NGHIÊN CỨU QUẦN XÃ VI KHUẨN TRONG NEM CHUA BẰNG PHƯƠNG PHÁP KHÔNG PHỤ THUỘC VÀO NUÔI CẤY

Phương pháp điện di trên gel với dải nồng độ chất biến (PCR –DGGE) đang được ứng dụng trong thời gian gần đây ở nhiều phòng thí nghiệm trên thế giới để xác định và quan sát hệ vi sinh vật trong thực phẩm. Trong nghiên cứu này PCR – DGGE được dùng để đánh giá sự đa dạng vi khuẩn trong nem chua và đặc biệt quan tâm tới chủng vi khuẩn hay gặp, góp phần nghiên cứu chọn, tạo chủng khởi động cho sản xuất nem chua có chất lượng tốt và an toàn. DNA tổng số được tách chiết trực tiếp từ 10 mẫu nem chua. PCR của vùng biến đổi V3 16S rDNA được sử dụng cho phân tích DGGE. Kết quả nghiên cứu chỉ ra trong nem chua Hà Nội và Thanh Hóa thu được các băng khác nhau liên quan đến các loài vi sinh vật trong nem chua, 53 băng được thu nhận. Sau đó, 53 băng này được cắt, tinh sạch, xác định trình tự và so sánh với trình tự đã biết trong ngân hàng gene EMBL. Kết quả đã chỉ ra hầu hết vi khuẩn trong nem chua Hà Nội và Thanh Hóa là vi khuẩn lactic trong đó có các chi là Lactobacillus, Lactococcus, Pediococcus, Leuconostoc, Vagococcus, Enterococcus, Weissella chỉ có hai chi Macrococcus, Psychrobacter không thuộc vi khuẩn lactic. Kết quả cũng chỉ ra ràng trong các chi vi khuẩn lactic thì Lactobacillus có số lượng lớn nhất, chúng có vai trò đặc biệt quan trọng trong tạo hương, bacteriocin để đảm bảo chất lượng cũng như trong việc bảo quản nem chua

Burkholderia cepacia complex taxon K : where to split?

The objective of the present study was to provide an updated classification for Burkholderia cepacia complex (Bcc) taxon K isolates. A representative set of 39 taxon K isolates were analyzed through multilocus sequence typing (MLST) and phylogenomic analyses. MLST analysis revealed the presence of at least six clusters of sequence types (STs) within taxon K, two of which contain the type strains of Burkholderia contaminans (ST-102) and Burkholderia lata (ST-101), and four corresponding to the previously defined taxa Other Bcc groups C, G, H and M. This clustering was largely supported by a phylogenomic tree which revealed three main clades. Isolates of B. contaminans and of Other Bcc groups C, G, and H represented a first clade which generally shared average nucleotide identity (ANI) and average digital DNA-DNA hybridization (dDDH) values at or above the 95–96% ANI and 70% dDDH thresholds for species delineation. A second clade consisted of Other Bcc group M bacteria and of four B. lata isolates and was supported by average ANI and dDDH values of 97.2 and 76.1% within this clade and average ANI and dDDH values of 94.5 and 57.2% toward the remaining B. lata isolates (including the type strain), which represented a third clade. We therefore concluded that isolates known as Other Bcc groups C, G, and H should be classified as B. contaminans, and propose a novel species, Burkholderia aenigmatica sp. nov., to accommodate Other Bcc M and B. lata ST-98, ST-103, and ST-119 isolates. Optimized MALDI-TOF MS databases for the identification of clinical Burkholderia isolates may provide correct species-level identification for some of these bacteria but would identify most of them as B. cepacia complex. MLST facilitates species-level identification of many taxon K strains but some may require comparative genomics for accurate species-level assignment. Finally, the inclusion of Other Bcc groups C, G, and H into B. contaminans affects the phenotype of this species minimally and the proposal to classify Other Bcc group M and B. lata ST-98, ST-103, and ST-119 strains as a novel Burkholderia species is supported by a distinctive phenotype, i.e., growth at 42°C and lysine decarboxylase activity

Comparative genomics of Pandoraea, a genus enriched in xenobiotic biodegradation and metabolism

Comparative analysis of partial gyrB, recA, and gltB gene sequences of 84 Pandoraea reference strains and field isolates revealed several clusters that included no taxonomic reference strains. The gyrB, recA, and gltB phylogenetic trees were used to select 27 strains for whole-genome sequence analysis and for a comparative genomics study that also included 41 publicly available Pandoraea genome sequences. The phylogenomic analyses included a Genome BLAST Distance Phylogeny approach to calculate pairwise digital DNA-DNA hybridization values and their confidence intervals, average nucleotide identity analyses using the OrthoANIu algorithm, and a whole-genome phylogeny reconstruction based on 107 single-copy core genes using bcgTree. These analyses, along with subsequent chemotaxonomic and traditional phenotypic analyses, revealed the presence of 17 novel Pandoraea species among the strains analyzed, and allowed the identification of several unclassified Pandoraea strains reported in the literature. The genus Pandoraea has an open pan genome that includes many orthogroups in the 'Xenobiotics biodegradation and metabolism' KEGG pathway, which likely explains the enrichment of these species in polluted soils and participation in the biodegradation of complex organic substances. We propose to formally classify the 17 novel Pandoraea species as P. anapnoica sp. nov. (type strain LMG 31117(T) = CCUG 73385(T)), P. anhela sp. nov. (type strain LMG 31108(T) = CCUG 73386(T)), P. aquatica sp. nov. (type strain LMG 31011(T) = CCUG 73384(T)), P. bronchicola sp. nov. (type strain LMG 20603(T) = ATCC BAA-110(T)), P. capi sp. nov. (type strain LMG 20602(T) = ATCC BAA-109(T)), P. captiosa sp. nov. (type strain LMG 31118(T) = CCUG 73387(T)), P. cepalis sp. nov. (type strain LMG 31106(T) = CCUG 39680(T)), P. commovens sp. nov. (type strain LMG 31010(T) = CCUG 73378(T)), P. communis sp. nov. (type strain LMG 31110(T) = CCUG 73383(T)), P. eparura sp. nov. (type strain LMG 31012(T) = CCUG 73380(T)), P. horticolens sp. nov. (type strain LMG 31112(T) = CCUG 73379(T)), P. iniqua sp. nov. (type strain LMG 31009(T) = CCUG 73377(T)), P. morbifera sp. nov. (type strain LMG 31116(T) = CCUG 73389(T)), P. nosoerga sp. nov. (type strain LMG 31109(T) = CCUG 73390(T)), P. pneumonica sp. nov. (type strain LMG 31114(T) = CCUG 73388(T)), P. soli sp. nov. (type strain LMG 31014(T) = CCUG 73382(T)), and P. terrigena sp. nov. (type strain LMG 31013(T) = CCUG 73381(T))

Lactobacillus porcinae sp. nov. isolated from traditional Vietnamese nem chua

A species diversity study of lactic acid bacteria occurring in traditional Vietnamese nem chua yielded an isolate, LMG 26767T, that could not be assigned to a validly named species. The isolate was initially investigated by 16S rRNA gene sequence analysis, which revealed that it belonged to the genus Lactobacillus, with Lactobacillus manihotivorans and Lactobacillus camelliae as the closest relatives (98.9% and 96.9% gene sequence similarity towards the type strains, respectively). Comparative (GTG)5-PCR genomic fingerprinting confirmed the unique taxonomic status of the novel strain. DNA-DNA hybridization experiments, DNA G+C content determination, sequence analysis of the phenylalanyl-tRNA synthase (pheS) gene, and physiological and biochemical characterization demonstrated that strain LMG 26767T (= CCUG 62266T) represents a novel species, for which the name Lactobacillus porcinae sp. nov. is proposed. Biochemically, Lb. porcinae can be distinguished from Lb. manihotivorans and Lb. camelliae by its carbohydrate fermentation profile, absence of growth at 45°C, and production of D- and L- lactate as end products of glucose metabolism

Characterization of Mycobacterium chelonae-like strains by comparative genomics

Isolates of the Mycobacterium chelonae-M. abscessus complex are subdivided into four clusters (CHI to CHIV) in the INNO-LiPA (R) Mycobacterium spp DNA strip assay. A considerable phenotypic variability was observed among isolates of the CHII cluster. In this study, we examined the diversity of 26 CHII cluster isolates by phenotypic analysis, drug susceptibility testing, whole genome sequencing and single-gene analysis. Pairwise genome comparisons were performed using several approaches, including average nucleotide identity (ANI) and genome-to-genome distance (GGD) among others. Based on ANI and GGD the isolates were identified as M. chelonae (14 isolates), M. franklinii (2 isolates) and M. salmoniphium (1 isolate). The remaining 9 isolates were subdivided into three novel putative genomospecies. Phenotypic analyses including drug susceptibility testing, as well as whole genome comparison by TETRA and delta differences, were not helpful in separating the groups revealed by ANI and GGD. The analysis of standard four conserved genomic regions showed that rpoB alone and the concatenated sequences clearly distinguished the taxonomic groups delimited by whole genome analyses. In conclusion, the CHII INNO-LiPa is not a homogeneous cluster; on the contrary, it is composed of closely related different species belonging to the M. chelonae-M. abscessus complex and also several unidentified isolates. The detection of these isolates, putatively novel species, indicates a wider inner variability than the presently known in this complex