AidP, a novel N-Acyl Homoserine Lactonase gene from Antarctic Planococcus sp.

Planococcus is a Gram-positive halotolerant bacterial genus in the phylum Firmicutes, commonly found in various habitats in Antarctica. Quorum quenching (QQ) is the disruption of bacterial cell-to-cell communication (known as quorum sensing), which has previously been described in mesophilic bacteria. This study demonstrated the QQ activity of a psychrotolerant strain, Planococcus versutus strain L10.15T, isolated from a soil sample obtained near an elephant seal wallow in Antarctica. Whole genome analysis of this bacterial strain revealed the presence of an N-acyl homoserine lactonase, an enzyme that hydrolyzes the ester bond of the homoserine lactone of N-acyl homoserine lactone (AHLs). Heterologous gene expression in E. coli confirmed its functions for hydrolysis of AHLs, and the gene was designated as aidP (autoinducer degrading gene from Planococcus sp.). The low temperature activity of this enzyme suggested that it is a novel and uncharacterized class of AHL lactonase. This study is the first report on QQ activity of bacteria isolated from the polar regions

Complete genome of Planococcus rifietoensis M8T, a halotolerant and potentially plant growth promoting bacterium

Planococcus rifietoensis M8T (=DSM 15069T = ATCC BAA-790T) is a halotolerant bacterium with potential plant growth promoting properties isolated from an algal mat collected from a sulfurous spring in Campania (Italy). This paper presents the first complete genome of P. rifietoensis M8T. Genes coding for various potentially plant growth promoting properties were identified within its genome

Complete genome of Pseudomonas sp. strain L10.10, a psychrotolerant biofertilizer that could promote plant growth

Pseudomonas sp. strain L10.10 (=DSM 101070) is a psychrotolerant bacterium which was isolated from Lagoon Island, Antarctica. Analysis of its complete genome sequence indicates its possible role as a plant-growth promoting bacterium, including nitrogen-fixing ability and indole acetic acid (IAA)-producing trait, with additional suggestion of plant disease prevention attributes via hydrogen cyanide production

Pseudomonas versuta sp. nov., isolated from Antarctic soil

In this study we used a polyphasic taxonomy approach to analyse three bacterial strains coded L10.10T, A4R1.5 and A4R1.12, isolated in the course of a study of quorum-quenching bacteria occurring Antarctic soil. The 16S rRNA gene sequence was identical in the three strains and showed 99.7% pairwise similarity with respect to the closest related species Pseudomonas weihenstephanensis WS4993T, and the next closest related species were P. deceptionensis M1T (99.5%), P. psychrophila E-3T, P. endophytica BSTT44T and P. fragi ATCC 4973T (99.2%). Therefore, the three strains were classified within the genus Pseudomonas. Analysis of housekeeping genes (rpoB, rpoD and gyrB) sequences showed similarities of 84-95% with respect to the closest relatives, confirming its phylogenetic affiliation. The whole genome average nucleotide identity (ANI) values were more than 99% similar among the three strains, and less than 86% to the closest related species type strains. The respiratory quinone is Q9. The major fatty acids are C16:0, C16:1 ω7c/C16:1 ω6c in summed feature 3 and C18:1 ω7c/C18:1 ω6c in summed feature 8. The strains are oxidase- and catalase-positive. The arginine dihydrolase and urease tests are positive. Growth occurs at 4–30 °C with an optimum at 28 °C, and at pH 4.0–10. The DNA G + C content is 58.2–58.3 mol %. The combined genotypic, phenotypic and chemotaxonomic data support the classification of strains L10.10T, A4R1.5 and A4R1.12 into a novel species of Pseudomonas, for which the name P. versuta sp. nov. is proposed. The type strain is L10.10T (LMG 29628T, DSM 101070T)

Planococcus versutus sp. nov., isolated from soil

A taxonomic study was performed on a novel Gram-stain-positive, coccus-shaped, orange-pigmented motile bacterium, designated as strain L10.15T. The organism was isolated from a soil sample collected in Lagoon Island (close to Adelaide Island, western Antarctic Peninsula) using a quorum-quenching enrichment medium. Growth occurred at 4–30 °C, pH 6–11 and at moderately high salinity (0–15 %, w/v, NaCl), with optimal growth at 26 °C, at pH 7–8 and with 6 % (w/v) NaCl. 16S rRNA gene sequence analysis showed that strain L10.15T belonged to the genus Planococcus and was closely related to Planococcus halocryophilus Or1T (99.3 % similarity), Planococcus donghaensis JH1T (99.0 %), Planococcus antarcticus DSM 14505T (98.3 %), Planococcus plakortidis AS/ASP6 (II)T (97.6 %), Planococcus maritimus TF-9T (97.5 %), Planococcus salinarum ISL-6T (97.5 %) and Planococcus kocurii NCIMB 629T (97.5 %). However, the average nucleotide identity-MUMmer analysis showed low genomic relatedness values of 71.1–81.7 % to the type strains of these closely related species of the genus Planococcus . The principal fatty acids were anteiso-C15 : 0, C16 : 1ω7c and anteiso-C17 :  0, and the major menaquinones of strain L10.15T were MK-5 (48 %), MK-6 (6 %) and MK-7 (44 %). Polar lipid analysis revealed the presence of phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol and aminophospholipid. The DNA G+C content was 39.4 mol%. The phenotypic and genotypic data indicate that strain L10.15T represents a novel species of the genus Planococcus , for which the name Planococcus versutus sp. nov. is proposed. The type strain is L10.15T (=DSM 101994T=KACC 18918T)

De novo assembly of complete genome sequence of Planococcus kocurii ATCC 43650T, a potential plant growth-promoting bacterium

Planococcus kocurii ATCC 43650T is a halotolerant and psychrotolerant bacterium isolated from the skin of a North sea cod. Here, we present the first complete genome and annotation of P. kocurii ATCC 43650T, identifying its potential as a plant growth promoting bacterium and its capability in the biosynthesis of butanol

Complete genome sequence of Planococcus donghaensis JH1T, a pectin-degrading bacterium

The type strain Planococcus donghaensis JH1T is a psychrotolerant and halotolerant bacterium with starch-degrading ability. Here, we determine the carbon utilization profile of P. donghaensis JH1T and report the first complete genome of the strain. This study revealed the strain’s ability to utilize pectin and d-galacturonic acid, and identified genes responsible for degradation of the polysaccharides. The genomic information provided may serve as a fundamental resource for full exploration of the biotechnological potential of P. donghaensis JH1T

Genomic and phylogenomic insights into the family Streptomycetaceae lead to the proposal of six novel genera

The family Streptomycetaceae is a large and diverse family within the phylum Actinomycetota . The members of the family are known for their ability to produce medically important secondary metabolites, notably antibiotics. In this study, 19 type strains showing low 16S rRNA gene similarity (<97.3 %) to other members of the family Streptomycetaceae were identified and their high genetic diversity was reflected in a phylogenomic analysis using conserved universal proteins. This analysis resulted in the identification of six distinct genus-level clades, with two separated from the genus Streptacidiphilus and four separated from the genus Streptomyces . Compared with members of the genera Streptacidiphilus and Streptomyces , average amino acid identity (AAI) analysis of the novel genera identified gave values within the range of 63.9–71.3 %, as has been previously observed for comparisons of related but distinct bacterial genera. The whole-genome phylogeny was reconstructed using PhyloPhlAn 3.0 based on an optimized subset of conserved universal proteins, the results of AAI and percentage of conserved proteins (POCP) analyses indicated that these phylogenetically distinct taxa may be assigned to six novel genera, namely Actinacidiphila gen. nov., Mangrovactinospora gen. nov., Peterkaempfera gen. nov., Phaeacidiphilus gen. nov., Streptantibioticus gen. nov. and Wenjunlia gen. nov

Quorum sensing and quorum quenching abilities of selected bacteria isolated from antarctic / See-Too Wah Seng

Quorum sensing (QS) is a phenomenon which refers to bacterial cell-to-cell communication in a population manner. QS regulates diverse activities in bacteria. Bacteria that possess QS activity communicate through secreted signal molecules or autoinducer. The Gram-negative bacteria and archaeon use acyl homoserine lactones (AHLs) as a QS signal to achieve regulation through the luxI-luxR homolog system, wheareas Gram-positive bacteria use small peptides as autoinducers. Some of the Proteobacteria use quinolone compound as signaling molecules. Quorum quenching (QQ) on the other hand refers to interference of QS that inactivates the signaling molecules. Even though QS and QQ were extensively studied in mesophilic bacteria, much less studies were conducted on bacteria that live in extreme environments. So far, there is no reported studies on QS and QQ in Antarctic bacteria. This study aimed to isolate N-acyl homoserine lactone producing and degrading bacteria from soil samples that were collected at different sites in Antarctica. The present work had successfully isolated 36 bacteria which produced N-acyl homoserine lactone, and 22 bacteria which degraded a variety of N-acyl homoserine lactone or quinolone signaling molecules. A few bacterial isolates including Flavobacterium sp., Poloromonas sp., Simplicispira sp., Planococcus sp. and Psychrobacter sp. has not been reported to possess any QS or QQ activity. To the best of our knowledge, this thesis is the first report of QS and QQ activities in Antarctic bacteria. Other N-acyl homoserine lactone producing bacterial isolates were Pseudomonas sp., and Acinetobacter sp., and they were found to produce long chain AHLs including C12-HSL and 3-oxo-C15-HSL through the use of liquid chromatography mass spectrometry (LCMS). QQ activity was also found in the N-acyl homoserine lactone producing Pseudomonas sp., Acinetobacter sp., and in Gram-positive bacterial isolates, Bacillus sp. and Athrobacter sp. All the bacteria with QQ abilities degraded a different range of AHLs, confirmed through the use of rapid resolution liquid chromatography (RRLC). A few bacteria including Psychrobacteria, Planococcus and some of the Pseudomonas spp. were found to produce homoserine lactonase enzyme(s) that degraded the homoserine lactone ring of the signaling compound