Serratia silvae sp. nov., Isolated from Forest Soil

The Gram-negative, oxidase-negative, catalase-positive, rod-shaped strain Arafor3^T was isolated from forest soil (France). Comparative 16S rRNA gene analysis and phylogenetic analysis based on (1) multilocus sequence analysis (MLSA) with four housekeeping genes (atpD, gyrB, infB and rpoB) and (2) genomes indicated that strain Arafor3^T shared 98.83% 16S rRNA gene sequence similarity with the type strain of Serratia fonticola DSM 4576^T and was closely related to this same strain in the MLSA and in the phylogenomic tree reconstruction. Average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) comparisons of strain Arafor3^T with its nearest neighbor S. fonticola DSM 4576^T showed 93.5% identity and 55.7% sequence similarity, respectively, and were lower than the 96% and 70% species-level cut-off values relating to these analyses (Logan et al. in Int J Syst Evol Microbiol 59:2114-21, 2009, https://doi.org/10.1099/ijs.0.013649-0 ). The strain differed from S. fonticola in that it was urease and arginine dihydrolase negative. The major fatty acids of strain Arafor3^T are C_16:0, C_16:1 ω7c/C_16:1 ω6c, _C14:0, C_14:0 3-OH/_16:1 isoI, and C_18:1 ω7c. The major respiratory quinone is Q8. The polar lipid profile consisted of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, and 6 unknown lipids. The mol G + C% content of the genomic DNA of strain Arafor3^T was 53.49%. Hence, Arafor3^T represents a novel species within the genus Serratia, for which the name Serratia silvae sp. nov. is proposed. The type strain is Arafor3^T (=LMG 32338^T = CIP 111939^T).

Wound swabs versus biopsies to detect methicillin resistant Staphylococcus aureus in experimental equine wounds

OBJECTIVE

To compare: (1) the load and diversity of cultivatable bacterial species isolated from tissue biopsies with cultures from surface swabs, and (2) the ability of each technique to detect methicillin-resistant Staphylococcus aureus (MRSA) in a model of MRSA-infected equine wounds.

STUDY DESIGN

Experimental in vivo study.

ANIMALS

Three light-breed adult horses.

METHODS

Four 2.5 × 2.5 cm full-thickness skin wounds were created on the dorsolateral aspect of each forelimb. Five days later, each wound was inoculated with a pure culture of MRSA (ATCC 43300). One hundred microlitres of 0, 5 × 108 , 5 × 109 or 5 × 1010 colony forming units (CFU)/ml was used to inoculate each wound. Surface swabs (Levine technique) and tissue biopsy samples (3 mm punch biopsy) were obtained at 2, 7, 14, and 21 days after inoculation. Quantitative aerobic culture was performed using routine clinical techniques.

RESULTS

A similar bacterial profile was identified from the culture of each wound-sampling technique and there was moderate correlation (R = 0.49, P < .001) between the bacterial bioburdens. Agreement was fair (κ = 0.31; 95% CI, 0.129-0.505) between the sampling techniques in identification of MRSA. Methicillin-resistant Staphylococcus aureus was isolated more frequently (P = .016) from cultures of tissue biopsies (79%; 76/96) than from surface swabs (62%; 60/96).

CONCLUSION

Bacterial load and diversity did not differ between sampling techniques but MRSA was detected more often from the cultures of tissue biopsies.

CLINICAL SIGNIFICANCE

Tissue biopsy should be preferred to culture swab in wounds where MRSA is suspected.

Facility-specific 'house' microbiome ensures the maintenance of functional microbial communities into coffee beans fermentation: implications for source tracking

This work aimed at studying the unconfirmed hypothesis predicting the existence of a connection between coffee farm microbiome and the resulting spontaneous fermentation process. Using Illumina-based amplicon sequencing, 360 prokaryotes and 397 eukaryotes were identified from coffee fruits and leaves, over-ripe fruits, water used for coffee de-pulping, depulped coffee beans, soil, and temporal fermentation samples at an experimental farm in Honduras. Coffee fruits and leaves were mainly associated with high incidence of Enterobacteriaceae, Pseudomonas, Colletotrichum, and Cladosporium. The proportion of Enterobacteriaceae was increased when leaves and fruits were collected on the ground compared to those from the coffee tree. Coffee farm soil showed the richest microbial diversity with marked presence of Bacillus. Following the fermentation process, microorganisms present in depulped coffee beans (Leuconostoc, Gluconobater, Pichia, Hanseniaspora, and Candida) represented more than 90% of the total microbial community, which produced lactic acid, ethanol, and several volatile compounds. The community ecology connections described in this study showed that coffee fruit provides beneficial microorganisms for the fermentation process. Enterobacteria, Colletotrichum, and other microbial groups present in leaves, fruit surface, over-ripe fruits, and soil may transfer unwanted aromas to coffee beans, so they should be avoided from having access to the fermentation tank.

Genomic diversity of Serratia proteamaculans and Serratia liquefaciens predominant in seafood products and spoilage potential analyses

Serratia sp. cause food losses and waste due to spoilage; it is noteworthy that they represent a dominant population in seafood. The main spoilage associated species comprise S. liquefaciens, S. grimesii, S. proteamaculans and S. quinivorans, also known as S. liquefaciens-like strains. These species are difficult to discriminate since classical 16S rRNA gene-based sequences do not possess sufficient resolution. In this study, a phylogeny based on the short-length luxS gene was able to speciate 47 Serratia isolates from seafood, with S. proteamaculans being the main species from fresh salmon and tuna, cold-smoked salmon, and cooked shrimp while S. liquefaciens was only found in cold-smoked salmon. The genome of the first S. proteamaculans strain isolated from the seafood matrix (CD3406 strain) was sequenced. Pangenome analyses of S. proteamaculans and S. liquefaciens indicated high adaptation potential. Biosynthetic pathways involved in antimicrobial compounds production and in the main seafood spoilage compounds were also identified. The genetic equipment highlighted in this study contributed to gain further insights into the predominance of Serratia in seafood products and their capacity to spoil.

Bruguierivorax albus gen. nov. sp. nov. Isolated from Mangrove Sediment and Proposal of Bruguierivoracaceae fam. nov

A novel Gram-negative, motile, aerobic rod-shaped bacterium designated BGMRC 2031^T was isolated from mangrove sediment collected from Guangxi Province, China. Optimal growth occurred at 28 °C and pH 7.0-8.0 in the presence of 1% (w/v) NaCl. Alignment based on 16S rRNA gene sequences indicated that strain BGMRC 2031^T is most closely related to Sodalis praecaptivus HS1^T (95.6%, sequence similarity), followed by Biostraticola tofi DSM 19580^T (95.5%), Sodalis glossinidius DSM 16929^T (95.4%), and Brenneria goodwinii FRB141^T (94.9%) sequence similarity. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain BGMRC 2031^T formed a distinct branch in a robust cluster and revealed that strain BGMRC 2031^T, genera Biostraticola and Sodalis, formed a novel family-level clade in the order Enterobacterales. The novel strain showed an average nucleotide similarity of 74.7%, 74.2%, and 73.1% for S. praecaptivus HS1^T, S. glossinidius DSM 16929^T, and B. tofi DSM 19580^T, respectively. The genomes of the BGMRC 2031^T shared the presence of a riboflavin synthesis gene cluster. The menaquinones of strain BGMRC 2031^T were MK-8 and Q-8, which were similar to those of genus Biostraticola. The major fatty acids (> 10%) were C_16:0 (19.9%), summed feature 2 (iso-C_16:1 and/or C_14:0 3-OH, 18.10%), summed feature 3 (C_16:1 ω7c and/or C_16:1 ω6c, 15.3%), C_12:0 (13.9%), C_17:0 cyclo (11.4%), and C_14:0 (10.4%). The main polar lipids were phosphatidyl methylethanolamine, phosphatidyl glycerol, diphosphatidyl glycerol, phosphatidyl inositol, one unidentified phospholipid, and one unknown polar lipid. The G+C content of strain BGMRC 2031^T was 55.4%. Strain BGMRC 2031^T could extend the mean lifespan and maximum lifespan of Caenorhabditis elegans by 4.5% and 12.5%, respectively. Overall, the results of this study indicate that BGMRC 2031^T is a novel species in a new genus, for which the name Bruguierivorax albus gen. nov. sp. nov. is proposed, and the type of strain is designated as BGMRC 2031^T (= NBRC 111907^T = KCTC 52119^T). In addition, a novel family, Bruguierivoracaceae fam. nov., is proposed to accommodate the genera Bruguierivorax, Biostraticola, and Sodalis.

Complete genome sequence of the biocontrol agent Serratia marcescens strain N4-5 uncovers an assembly artefact

Serratia marcescens are gram-negative bacteria found in several environmental niches, including the plant rhizosphere and patients in hospitals. Here, we present the genome of Serratia marcescens strain N4-5 (=NRRL B-65519), which has a size of 5,074,473 bp (664-fold coverage) and contains 4840 protein coding genes, 21 RNA genes, and an average G + C content of 59.7%. N4-5 harbours a plasmid of 11,089 bp and 43.5% G + C content that encodes six unique CDS repeated 2.5× times totalling 13 CDS. Our genome assembly and manual curation uncovered the insertion of two extra copies of the 5S rRNA gene in the assembled sequence, which was confirmed by PCR and Sanger sequencing to be a misassembly. This artefact was subsequently removed from the final assembly. The occurrence of extra copies of the 5S rRNA gene was also observed in most complete genomes of Serratia spp. deposited in public databases in our comparative analysis. These elements, which also occur naturally, can easily be confused with true genetic variation. Efforts to discover and correct assembly artefacts should be made in order to generate genome sequences that represent the biological truth underlying the studied organism. We present the genome of N4-5 and discuss genes potentially involved in biological control activity against plant pathogens and also the possible mechanisms responsible for the artefact we observed in our initial assembly. This report raises awareness about the extra copies of the 5S rRNA gene in sequenced bacterial genomes as they may represent misassemblies and therefore should be verified experimentally.

Serratia inhibens sp. nov., a new antifungal species isolated from potato (Solanum tuberosum)

A novel bacterial strain, S40T, with strong antifungal activity was isolated from the rhizosphere of green potato collected from Zealand, Denmark. Polyphasic analysis with a combined phenotypic, phylogenetic and genomic approach was used to characterize S40T. Phylogenetic analysis based on the 16S rRNA gene and MLSA (concatenated gyrB, rpoD, infB and atpD sequences) showed that strain S40T was affiliated with the genus Serratia and with Serratia plymuthica PRI-2C as the closest related strain [average nucleotide identity (ANI), 99.26 %; DNA–DNA hybridization (dDDH), 99.20%]. However, whole genome sequence analyses revealed that S40T and S. plymuthica PRI-2C genomes displayed lower similarities when compared to all other S. plymuthica strains (ANI ≤94.34 %; dDDH ≤57.6 % relatedness). The DNA G+C content of strain S40T was determined to be 55.9 mol%. Cells of the strain were Gram-negative, rod-shaped, facultative anaerobic and displayed growth at 10–37 °C (optimum, 25–30 °C) and at pH 6–9 (optimum, pH 6–7). Major fatty acids were C16 : 0 (27.9 %), summed feature (C16 : 1  ω6c/C16 : 1 ω7c; 18.0 %) and C17 : 0 cyclo (15.1 %). The respiratory quinone was determined to be Q8 (94 %) and MK8 (95 %) and the major polar lipids were phosphatidylethanolamine and phosphatidylglycerol. The results of phenotypic, phylogenetic and genomic analyses support the hypothesis that strain S40T represents a novel species of the genus Serratia , for which the name Serratia inhibens sp. nov. is proposed. The type strain is S40T (=LMG 31467T=NCIMB 15235T). In addition, we propose that S. plymuthica PRI-2C is reclassified and transferred to the species S. inhibens as S. inhibens PRI-2C.

Genomic characterization of a pectinolytic isolate of Serratia oryzae isolated from lake water

Only one isolate of Serratia oryzae, the type strain J11-6T has been characterized up to now. This strain was found in the endophytic bacterial flora of rice. As part of an ongoing investigation into pectinolytic bacteria present in lake water in France, a few Serratia strains were isolated, including S32 and J9 identified as new strains of S. oryzae. The genome of strain S32 consists of a circular chromosome of 4,810,389 bp that contains 4,584 protein-coding genes. The genome of S32, as well as those of the type strain J11-6T, contains several genes involved in pectin degradation and in the intracellular assimilation of pectin oligomers. The specific detection of enzyme activities confirmed that strain S32 secretes functional pectinases and that it also produces extracellular cellulase and protease activities. The ability to produce plant cell wall degrading enzymes shows that S. oryzae shares characteristics of plant associated bacteria, including phytopathogens.

An Update on the Novel Genera and Species and Revised Taxonomic Status of Bacterial Organisms Described in 2016 and 2017

Recognition and acknowledgment of novel bacterial taxonomy and nomenclature revisions can impact clinical practice, disease epidemiology, and routine clinical microbiology laboratory operations. The Journal of Clinical Microbiology (JCM) herein presents its biannual report summarizing such changes published in the years 2016 and 2017, as published and added by the International Journal of Systematic and Evolutionary Microbiology Noteworthy discussion centers around descriptions of novel Corynebacteriaceae and an anaerobic mycolic acid-producing bacterium in the suborder Corynebacterineae; revisions within the Propionibacterium, Clostridium, Borrelia, and Enterobacter genera; and a major reorganization of the family Enterobacteriaceae. JCM intends to sustain this series of reports as advancements in molecular genetics, whole-genome sequencing, and studies of the human microbiome continue to produce novel taxa and clearer understandings of bacterial relatedness.

Taxonomy and systematics of plant probiotic bacteria in the genomic era

Recent decades have predicted significant changes within our concept of plant endophytes, from only a small number specific microorganisms being able to colonize plant tissues, to whole communities that live and interact with their hosts and each other. Many of these microorganisms are responsible for health status of the plant, and have become known in recent years as plant probiotics. Contrary to human probiotics, they belong to many different phyla and have usually had each genus analysed independently, which has resulted in lack of a complete taxonomic analysis as a group. This review scrutinizes the plant probiotic concept, and the taxonomic status of plant probiotic bacteria, based on both traditional and more recent approaches. Phylogenomic studies and genes with implications in plant-beneficial effects are discussed. This report covers some representative probiotic bacteria of the phylum Proteobacteria, Actinobacteria, Firmicutes and Bacteroidetes, but also includes minor representatives and less studied groups within these phyla which have been identified as plant probiotics.