Paenibacillus phoenicis sp. nov., isolated from the Phoenix Lander assembly facility and a subsurface molybdenum mine

Ultraviolet and biological effective dose observations at Gale Crater, Mars

The incident ultraviolet (UV) irradiance on the surface of Mars is strongly sterilizing and plays a critical role in atmospheric and near-surface photochemistry. The Rover Environmental Monitoring Station (REMS) instrument, which includes the first UV sensor sent to Mars on board the Curiosity rover, has been measuring the UV irradiance at Gale Crater since 2012, providing ground-truth data regarding seasonal and short-term variability of the UV radiation at the surface of another planet. Here, we analyze the REMS UV measurements for a period of >5 Martian years to retrieve biological effective doses and other UV radiation quantities on the planetary surface that are key for different physicochemical processes. Our results reveal a previously unidentified complex UV radiation environment on the Martian surface, with dramatic short-term fluctuations capable of changing UV radiation doses by >30% in a few sols. We assess the viability of terrestrial microorganisms exposed to this UV radiation field and dispersed through the Martian atmosphere from a robotic spacecraft or human habitat. Our findings show that reducing microbial viability by 99% would require several hours of exposure to the Martian environment including during the daytime, a finding that may call for a reinforcement of planetary protection policies.

Whole-genome sequencing of Paenibacillus phoenicis isolated from the Phoenix Mars Lander spacecraft assembly facility

The genome of Paenibacillus phoenicis, a spore-forming bacterium isolated from the spacecraft assembly facility of the Phoenix mission, was generated via hybrid assembly by merging short and long reads. Examining this genome may shed light on strategies to minimize the risk of contaminating extraterrestrial environments with Earth-based microorganisms.

Paenibacillus caui sp. nov., a nitrogen-fixing species isolated from the rhizosphere soil of a peach tree

A nitrogen-fixing, endospore-forming, motile, rod-shaped, facultative aerobic bacterium, designated 81-11T, was isolated from rhizosphere soil of a peach tree collected from Handan, Hebei, PR China. From the comparison of 16S rRNA gene sequence, the strain is most closely related to Paenibacillus phoenicis DSM 27463T (96.9 %) and Paenibacillus faecis DSM 23593T (96.7 %). The genome size of strain 81-11T was 4.4 Mb, comprising 4879 predicted genes with a DNA G+C content of 50.0 mol%. The average nucleotide identity values of genome sequences between the novel isolate and the type strains of related species P. phoenicis DSM 27463T and P. faecis DSM 23593T were 71.8 and 72.1 %, respectively. The major cellular fatty acids were anteiso-C15 : 0(47.8 %), iso-C16 : 0 (15.5 %) and iso-C15 : 0 (13.0 %). Menaquinone-7 was the major respiratory quinone. The polar lipids contained phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, aminophospholipid, aminoglycopid, unknown polar lipids and unidentified aminophosphoglycolipid. Based on phylogenetic, genomic and phenotypic characteristics, strain 81-11T was classified as a novel species within the genus Paenibacillus , for which the name Paenibacillus caui sp. nov. is proposed. The type strain of Paenibacillus caui is 81-11T (=JCM 34618T=CGMCC 1.18907T).

Paenibacillus ottowii sp. nov. isolated from a fermentation system processing bovine manure

Strain MS2379^T was isolated from a pasteurized solution sample from a predominantly anaerobic fermentation system processing bovine manure in Pilot Point, Texas. Phylogenetic analyses based on both 16S rRNA gene and rpoB gene sequences showed that MS2379^T was most closely related to Paenibacillus polymyxa (DSM 36^T), P. jamilae (DSM 13815^T), and P. peoriae (DSM 8320^T), yet DNA-DNA relatedness through DNA-DNA hybridization revealed only 22.6, 32.0 and 24.7 % relatedness to these three species respectively. Rod-shaped cells of strain MS2379^T are Gram-stain variable with sub-terminal, ellipsoidal, deforming endospores. The peptidoglycan contains meso-diaminopimelic acid (mDAP) and the predominant fatty acids are anteiso-C_15 : 0 (61.9 %) and anteiso-C_17 : 0 (11.6 %), confirming that strain MS2379^T has diagnostic features of other Paenibacillus species. The G+C content of MS2379^T is 45.9 mol%. Fermentation of glucose yields acid and gas end-products. The polar lipids found were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, and glycolipids, but also included some unidentified lipids, aminolipids, aminoglycolipid, and phosphatidylmethylethanolamine. The growth range of MS2379^T was observed from 10-45 °C with optimal growth temperature at 30 °C. Growth was observed between pH 6-10 and up to 3 % NaCl. Unlike the most closely related Paenibacillus species, strain MS2379^T was negative in the Voges-Proskauer reaction. Nucleic acid, chemotaxonomic and biochemical features support the distinctiveness of strain MS2379^T. Thus, strain MS2379^T represents a novel species of the genus Paenibacillus for which the name Paenibacillus ottowii sp. nov. is proposed with the type strain MS2379^T (=DSM 107750^T=ATCC TSD-165^T).

Bacillus glennii sp. nov. and Bacillus saganii sp. nov., isolated from the vehicle assembly building at Kennedy Space Center where the Viking spacecraft were assembled

Two Gram-stain-positive, motile, endospore-forming, aerobic strains, designated V44-8^T and V47-23a^T, were isolated from environmental air sampling at the vehicle assembly building at Cape Canaveral, Florida, where the Viking spacecraft were assembled. Growth was observed at pH 7-9 (optimum, pH 9) for strain V44-8^T, and pH 5-10 (pH 9) for strain V47-23a^T. Both strains displayed growth in 0-5 % NaCl with an optimum at 1 % for strain V44-8^T; 0 % for strain V47-23a^T. Strains V44-8^T and V47-23a^T grew optimally at 32 °C, (15-32 °C) and 25 °C (20-45 °C), respectively. The cell wall of both strains contained meso-diaminopimelic acid as the diagnostic diamino acid. Both strains contained phosphatidylglycerol, phosphatidylethanolamine and diphosphatidylglycerol. The predominant cellular fatty acids were anteiso-C_15 : 0, iso-C_14 : 0 and iso-C_15 : 0. Strain V47.23a^T shared its highest 16S rRNA sequence similarity with Bacillus cavernae DSM-105484^T at 96.9%, and V44.8^T with Bacillus zeae DSM-103964^T at 96.6 %. Based on their phenotypic characteristics and phylogenetic position inferred from 16S rRNA gene sequence analyses, the isolates were identified as being a members of the genus Bacillus that forms a separate clade when compared to close relatives. Average nucleotide identity and average amino acid identity values between strains V44-8^T and DSM-103964^T were 72.1% and 67.5 %; V47-23a^T and DSM-105484^T were 62.4% and 69.1%, respectively. Based on the phenotypic, genomic and biochemical data, strains V44-8^T and V47-23a^T represent two novel species in the genus Bacillus for which the names Bacillus glennii sp. nov. [type strain, V44-8^T (=ATCC BAA-2860^T =DSM 105192^T)], and Bacillus saganii sp. nov. [V47-23a^T (=ATCC BAA-2861^T=DSM 105190^T)] are proposed.

Biological Contamination Prevention for Outer Solar System Moons of Astrobiological Interest: What Do We Need to Know?

To ensure that scientific investments in space exploration are not compromised by terrestrial contamination of celestial bodies, special care needs to be taken to preserve planetary conditions for future astrobiological exploration. Significant effort has been made and is being taken to address planetary protection in the context of inner Solar System exploration. In particular for missions to Mars, detailed internationally accepted guidelines have been established. For missions to the icy moons in the outer Solar System, Europa and Enceladus, the planetary protection requirements are so far based on a probabilistic approach and a conservative estimate of poorly known parameters. One objective of the European Commission-funded project, Planetary Protection of Outer Solar System, was to assess the existing planetary protection approach, to identify inherent knowledge gaps, and to recommend scientific investigations necessary to update the requirements for missions to the icy moons.

Paenibacillus mobilis sp. nov., a Gram-stain-negative bacterium isolated from soil

A novel Gram-stain-negative bacterium, designated strain S8^T, was isolated from a soil sample obtained in Gyeonggi Province, Republic of Korea. Cells of strain S8^T were endospore-forming, motile by means of peritrichous flagella, and rod-shaped. S8^T colonies were round, convex, wavy and white. Strain S8^T grew optimally at 37 °C, pH 6-8, and up to 2.0 % (w/v) NaCl. Based on 16S rRNA gene sequence similarity, strain S8^T was affiliated with the genus Paenibacillus in the family Paenibacillaceae and was most closely related to Paenibacillus yonginensis DCY84^T and Paenibacillus physcomitrellae XB^T (98.8 and 97.1 % sequence similarity). The DNA G+C content of the novel strain was 53.1±0.3 mol%. Strain S8^T contained diphosphatidylglycerol, phosphatidylglycerol, two phospholipids, four aminophospholipids, an aminolipid and three unidentified lipids. The major fatty acid was anteiso-branched C15 : 0. The quinone was menaquinone MK-7. The peptidoglycan of strain S8^T contained meso-diaminopimelic acid. The DNA-DNA hybridization values of strain S8^T with P. yonginensis KCTC 33428^T and P. physcomitrellae DSM 29851^T were 44 % and 32 %, respectively. Data from the DNA-DNA hybridization, biochemical, phylogenetic and physiological analyses indicate that strain S8^T (=KCTC 33848^T=JCM 31672^T) represents a novel species of the genus Paenibacillus, for which the name Paenibacillus mobilis sp. nov. is proposed.

Non-Toxin-Producing Bacillus cereus Strains Belonging to the B. anthracis Clade Isolated from the International Space Station

The International Space Station Microbial Observatory (Microbial Tracking-1) study is generating a microbial census of the space station’s surfaces and atmosphere by using advanced molecular microbial community analysis techniques supported by traditional culture-based methods and modern bioinformatic computational modeling. This approach will lead to long-term, multigenerational studies of microbial population dynamics in a closed environment and address key questions, including whether microgravity influences the evolution and genetic modification of microorganisms. The spore-forming Bacillus cereus sensu lato group consists of pathogenic (B. anthracis), food poisoning (B. cereus), and biotechnologically useful (B. thuringiensis) microorganisms; their presence in a closed system such as the ISS might be a concern for the health of crew members. A detailed characterization of these potential pathogens would lead to the development of suitable countermeasures that are needed for long-term future missions and a better understanding of microorganisms associated with space missions.

In an ongoing Microbial Observatory investigation of the International Space Station (ISS), 11 Bacillus strains (2 from the Kibo Japanese experimental module, 4 from the U.S. segment, and 5 from the Russian module) were isolated and their whole genomes were sequenced. A comparative analysis of the 16S rRNA gene sequences of these isolates showed the highest similarity (>99%) to the Bacillus anthracis-B. cereus-B. thuringiensis group. The fatty acid composition, polar lipid profile, peptidoglycan type, and matrix-assisted laser desorption ionization–time of flight profiles were consistent with the B. cereus sensu lato group. The phenotypic traits such as motile rods, enterotoxin production, lack of capsule, and resistance to gamma phage/penicillin observed in ISS isolates were not characteristics of B. anthracis. Whole-genome sequence characterizations showed that ISS strains had the plcR non-B. anthracis ancestral “C” allele and lacked anthrax toxin-encoding plasmids pXO1 and pXO2, excluding their identification as B. anthracis. The genetic identities of all 11 ISS isolates characterized via gyrB analyses arbitrarily identified them as members of the B. cereus group, but traditional DNA-DNA hybridization (DDH) showed that the ISS isolates are similar to B. anthracis (88% to 90%) but distant from the B. cereus (42%) and B. thuringiensis (48%) type strains. The DDH results were supported by average nucleotide identity (>98.5%) and digital DDH (>86%) analyses. However, the collective phenotypic traits and genomic evidence were the reasons to exclude the ISS isolates from B. anthracis. Nevertheless, multilocus sequence typing and whole-genome single nucleotide polymorphism analyses placed these isolates in a clade that is distinct from previously described members of the B. cereus sensu lato group but closely related to B. anthracis.

IMPORTANCE The International Space Station Microbial Observatory (Microbial Tracking-1) study is generating a microbial census of the space station’s surfaces and atmosphere by using advanced molecular microbial community analysis techniques supported by traditional culture-based methods and modern bioinformatic computational modeling. This approach will lead to long-term, multigenerational studies of microbial population dynamics in a closed environment and address key questions, including whether microgravity influences the evolution and genetic modification of microorganisms. The spore-forming Bacillus cereus sensu lato group consists of pathogenic (B. anthracis), food poisoning (B. cereus), and biotechnologically useful (B. thuringiensis) microorganisms; their presence in a closed system such as the ISS might be a concern for the health of crew members. A detailed characterization of these potential pathogens would lead to the development of suitable countermeasures that are needed for long-term future missions and a better understanding of microorganisms associated with space missions.

Paenibacillus spp. isolated from human and environmental samples in Spain: detection of 11 new species

One hundred thirty-six isolates, 88 human and 48 environmental, that met the requirements to belong to the genus Paenibacillus were identified using a polyphasic taxonomic approach known as 16S rRNA plus phenotypic traits. Thirty-seven Paenibacillus species were identified; some had not been previously reported from clinical samples. The main species were P. pabuli (13 isolates), P. provencensis (11), P. phoenicis (9) and P. lautus (8). P. pabuli (11/13) and P. provencensis (8/11) were mainly environmental isolates, while P. phoenicis (9/9) and P. lautus (6/8) were mainly human isolates. Despite the difficulties in assigning to human Paenibacillus isolates a role as a pathogen or contaminant, here 25% of the isolates were involved in true infections, especially in those cases that affected abscesses, wound exudates, ocular infections and diverse fluids. In addition, 15 isolates were identified as 11 'Candidatus' to a new species, all of them from human specimens except one that was obtained from laboratory air. The antimicrobial susceptibility testing showed 95.6% of isolates were resistant to ampicillin, 44% were resistant to cotrimoxazole, 20 to 30% were resistant to cefotaxime and vancomycin and 13% were resistant to rifampicin and erythromycin.

Paenibacillus phocaensis sp. nov., isolated from the gut microbiota of a healthy infant

Paenibacillus phocaensis sp. nov. strain mt24T (= CSUR P2238 = DSM 101777) is a Gram-negative, facultative anaerobic, spore-forming and motile bacilli. This strain was isolated from the stool sample of a healthy infant from Niger. Its genome was estimated to a size of 5 521 415 bp with a 53.54% GC content. It contains 4835 protein-coding genes and 89 RNAs, among which two were 16S rRNA genes. There were also 101 genes (2.09%) identified as ORFans.

Paenibacillus cathormii sp. nov., isolated from tree bark

A Gram-stain-positive, facultatively anaerobic, rod-shaped and endospore-forming bacterium, strain BK114-2^T isolated from tree bark in Thailand was characterized taxonomically using a polyphasic approach. Analysis based on comparison of 16S rRNA gene sequences indicated that strain BK114-2^T was affiliated to the genus Paenibacillus, and was closely related to Paenibacillus timonensis 2301032^T (96.7 % 16S rRNA gene sequence similarity), Paenibacillus phoenicis 3PO2SA^T (96.6 %) and Paenibacillus barengoltzii SAFN-016^T (96.4 %). Strain BK114-2^T contained meso-diaminopimelic acid in its cell-wall peptidoglycan. The polar lipids were composed of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, two unknown phospholipids, five unknown aminophospholipids and six unknown lipids. The only menaquinone detected was MK-7 and the dominant cellular fatty acids were C_16 : 0 (22.9 %), anteiso-C_15 : 0 (22.6 %), iso-C_16 : 0 (19.4 %) and anteiso-C_17 : 0 (14.7 %). The DNA G+C content was 52.0 mol%. Based on these results, strain BK114-2^T repreesents a novel species of the genus Paenibacillus, for which the name Paenibacillus cathormii sp. nov. is proposed. The type strain is BK114-2^T ( = KCTC 33251^T = TISTR 2282^T).

Paenibacillus wenxiniae sp. nov., a nifH gene -harbouring endophytic bacterium isolated from maize

A novel Gram-positive, aerobic, motile, endospore-forming, rod-shaped bacterium, designated 373(T) was isolated from surface-sterilised root tissue of a maize planted in Fangshan District of Beijing, Peopole's Republic of China. A polyphasic taxonomic study was performed on the new isolate. On the basis of 16S rRNA gene sequence similarity studies, this isolate belongs to the genus Paenibacillus. The highest 16S rRNA gene sequence similarity was found between strain 373(T) and Paenibacillus hunanensis (98.1%), meanwhile the 16S rRNA gene sequence similarity between strain 373(T) and the type strains of other recognised members of the genus Paenibacillus were all below 95.6%. However, the DNA-DNA hybridization values between strain 373(T) and the type strain P. hunanensis DSM 22170(T) was 30.2%. The DNA G+C content of strain 373(T) was determined to be 46.0 mol%. The predominant respiratory quinone was identified as menaquinone-7 and the polar lipid profile was found to be composed of the major lipids diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. The major fatty acids were found to consist of anteiso-C15: 0 (59.6%), anteiso-C17: 0 (12.8%) and C16: 0 (6.7%). The results of physiological and biochemical tests and minor differences in the fatty acid profiles allowed a clear phenotypic differentiation of strain 373(T) from the closely related species in this genus Paenibacillus. Strain 373(T) is concluded to represent a novel species within the genus Paenibacillus, for which the name Paenibacillus wenxiniae sp. nov. is proposed, with the type strain 373(T) (= CGMCC 1.15007 (T) = DSM100576 ).

Paenibacillus guangzhouensis sp. nov., an Fe(III)- and humus-reducing bacterium from a forest soil

A Gram-reaction-variable, rod-shaped, motile, facultatively aerobic and endospore-forming bacterium, designated strain GSS02T, was isolated from a forest soil. Strain GSS02T was capable of reducing humic substances and Fe(III) oxides. Strain GSS02T grew optimally at 35 °C, at pH 78 and in the presence of 1 % NaCl. The predominant menaquinone was MK-7. The major cellular fatty acids were anteiso-C15 : 0 and iso-C16 : 0 and the polar lipid profile contained mainly phosphatidylethanolamine, diphosphatidylglycerol and phosphatidylglycerol, with moderate amounts of two unknown aminophospholipids and a minor amount of one unknown lipid. The DNA G+C content was 53.4 mol%. Comparative 16S rRNA gene sequence analysis showed that strain GSS02T was related most closely to Paenibacillus terrigena JCM 21741T (98.1 % similarity). Mean DNA–DNA relatedness between strain GSS02T and P. terrigena JCM 21741T was 58.8±0.5 %. The phylogenetic, chemotaxonomic and phenotypic results clearly demonstrated that strain GSS02T belongs to the genus Paenibacillus and represents a novel species, for which the name Paenibacillus guangzhouensis sp. nov. is proposed. The type strain is GSS02T ( = KCTC 33171T = CCTCC AB 2013236T).

Paenibacillus yonginensis sp. nov., a potential plant growth promoting bacterium isolated from humus soil of Yongin forest

Strain DCY84(T), a Gram-stain positive, rod-shaped, aerobic, spore-forming bacterium, motile by means of peritrichous flagella, was isolated from humus soil from Yongin forest in Gyeonggi province, South Korea. Strain DCY84(T) shared the highest sequence similarity with Paenibacillus barengoltzii KACC 15270(T) (96.86 %), followed by Paenibacillus timonensis KACC 11491(T) (96.49 %) and Paenibacillus phoenicis NBRC 106274(T) (95.77 %). Strain DCY84(T) was found to able to grow best in TSA at temperature 30 °C, at pH 8 and at 0.5 % NaCl. MK-7 menaquinone was identified as the isoprenoid quinone. The major polar lipids were identified as phosphatidylethanolamine, an unidentified aminophospholipid, two unidentified aminolipids and an unidentified polar lipid. The peptidoglycan was found to contain the amino acids meso-diaminopimelic acid, alanine and D-glutamic acid. The major fatty acids of strain DCY84(T) were identified as branched chain anteiso-C15:0, saturated C16:0 and branched chain anteiso-C17:0. The cell wall sugars of strain DCY84(T) were found to comprise of ribose, galactose and xylose. The major polyamine was identified as spermidine. The DNA G+C content was determined to be 62.6 mol%. After 6 days of incubation, strain DCY84(T) produced 52.96 ± 1.85 and 72.83 ± 2.86 µg/ml L-indole-3-acetic acid, using media without L-tryptophan and supplemented with L-tryptophan, respectively. Strain DCY84(T) was also found to be able to solubilize phosphate and produce siderophores. On the basis of the phenotypic characteristics, genotypic analysis and chemotaxonomic characteristics, strain DCY84(T) is considered to represent a novel species of the genus Paenibacillus, for which the name Paenibacillus yonginensis sp. nov. is proposed. The type strain is DCY84(T) (=KCTC 33428(T) = JCM 19885(T)).

Paenibacillus selenii sp. nov., isolated from selenium mineral soil

Strain W126(T), a Gram-reaction-positive, spore-forming, rod-shaped, facultatively anaerobic bacterium, motile by means of peritrichous flagella, was isolated from selenium mineral soil in Hubei province of China. 16S rRNA gene sequence analysis demonstrated that this isolate belonged to the genus Paenibacillus, with 97.9 % sequence similarity to Paenibacillus anaericanus MH21(T), while compared with the other species of the genus Paenibacillus, the 16S rRNA gene sequence similarities were less than 96.0%. DNA-DNA hybridization between strain W126(T) and Paenibacillus anaericanus DSM 15890(T) was 24%. The major isoprenoid menaquinone was menaquinone-7. Anteiso-C(15 : 0) was the major fatty acid. The DNA G+C content was 42.3 mol%. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, three unknown aminophospholipids and an unknown lipid. Strain W126(T) contained A1γ-meso-diaminopimelic acid in the cell-wall peptidoglycan. The phenotypic, chemotaxonomic and genotypic data indicate that strain W126(T) represents a novel species of the genus Paenibacillus, for which the name Paenibacillus selenii sp. nov. is proposed. The type strain is W126(T) ( = KCTC 33420(T) = CCTCC AB 2014003(T)).

Paenibacillus doosanensis sp. nov., isolated from soil

A Gram-stain-positive, aerobic, endospore-forming bacterium, designated CAU 1055T, was isolated from soil and its taxonomic position was investigated using a polyphasic approach. Phylogenetic analysis based on 16S rRNA gene sequence comparison revealed that the strain formed a distinct lineage within the genus Paenibacillus and was most closely related to Paenibacillus contaminans CKOBP-6T (similarity, 95.2 %) and Paenibacillus terrigena A35T (similarity, 95.2 %). The levels of 16S rRNA gene sequence similarity with other species of the genus Paenibacillus , including the type species of the genus, Paenibacillus polymyxa IAM 13419T (similarity, 91.7 %), were all <94.6 %. Strain CAU 1055T contained MK-7 as the only isoprenoid quinone and anteiso-C15 : 0 and iso-C16 : 0 as the major fatty acids. The cell-wall peptidoglycan of strain CAU 1055T contained meso-diaminopimelic acid. The polar lipids were composed of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, lysyl-phospatidylglycerol and three unidentified aminophospholipids. The DNA G+C content was 48.3 mol%. The results of physiological and biochemical tests allowed phenotypic differentiation of strain CAU 1055T from closely related recognized species. On the basis of phenotypic data and phylogenetic inference, strain CAU 1055T should be classified in the genus Paenibacillus , as a member of a novel species, for which the name Paenibacillus doosanensis sp. nov. is proposed. The type strain is CAU 1055T ( = KCTC 33036T = CCUG 63270T).

Deposition of extreme-tolerant bacterial strains isolated during different phases of Phoenix spacecraft assembly in a public culture collection

Extreme-tolerant bacteria (82 strains; 67 species) isolated during various assembly phases of the Phoenix spacecraft were permanently archived within the U.S. Department of Agriculture's Agricultural Research Service Culture Collection in Peoria, Illinois. This represents the first microbial collection of spacecraft-associated surfaces within the United States to be deposited into a freely available, government-funded culture collection. Archiving extreme-tolerant microorganisms from NASA mission(s) will provide opportunities for scientists who are involved in exploring microbes that can tolerate extreme conditions.

Utilization of low-pressure plasma to inactivate bacterial spores on stainless steel screws

A special focus area of planetary protection is the monitoring, control, and reduction of microbial contaminations that are detected on spacecraft components and hardware during and after assembly. In this study, wild-type spores of Bacillus pumilus SAFR-032 (a persistent spacecraft assembly facility isolate) and the laboratory model organism B. subtilis 168 were used to study the effects of low-pressure plasma, with hydrogen alone and in combination with oxygen and evaporated hydrogen peroxide as a process gas, on spore survival, which was determined by a colony formation assay. Spores of B. pumilus SAFR-032 and B. subtilis 168 were deposited with an aseptic technique onto the surface of stainless steel screws to simulate a spore-contaminated spacecraft hardware component, and were subsequently exposed to different plasmas and hydrogen peroxide conditions in a very high frequency capacitively coupled plasma reactor (VHF-CCP) to reduce the spore burden. Spores of the spacecraft isolate B. pumilus SAFR-032 were significantly more resistant to plasma treatment than spores of B. subtilis 168. The use of low-pressure plasma with an additional treatment of evaporated hydrogen peroxide also led to an enhanced spore inactivation that surpassed either single treatment when applied alone, which indicates the potential application of this method as a fast and suitable way to reduce spore-contaminated spacecraft hardware components for planetary protection purposes.

Paenibacillus catalpae sp. nov., isolated from the rhizosphere soil of Catalpa speciosa

A bacterial strain, designated D75(T), was isolated from the rhizosphere soil of Catalpa speciosa. Phylogenetic analysis based on the complete 16S rRNA gene sequence revealed that strain D75(T) was a member of the genus Paenibacillus. High levels of 16S rRNA gene sequence similarity were found between strain D75(T) and Paenibacillus glycanilyticus DS-1(T) (99.2 %), Paenibacillus xinjiangensis B538(T) (97.5 %) and Paenibacillus castaneae Ch-32(T) (97.2 %). The chemotaxonomic properties of strain D75(T) were consistent with those of the genus Paenibacillus: the cell-wall peptidoglycan type was based on meso-diaminopimelic acid (A1γ), the predominant menaquinone was MK-7, and the major fatty acids were anteiso-C15 : 0, iso-C16 : 0 and C16 : 0. However, levels of DNA-DNA relatedness between strain D75(T) and P. glycanilyticus NBRC 16618(T), P. xinjiangensis DSM 16970(T) and P. castaneae DSM 19417(T) were 35, 20 and 18 %, respectively. On the basis of phenotypic and chemotaxonomic analyses, phylogenetic data and DNA-DNA relatedness values, strain D75(T) is considered to represent a novel species of the genus Paenibacillus, for which the name Paenibacillus catalpae sp. nov. is proposed. The type strain is D75(T) ( = DSM 24714(T) = CGMCC 1.10784(T)).

Mutagenesis in bacterial spores exposed to space and simulated martian conditions: data from the EXPOSE-E spaceflight experiment PROTECT

As part of the PROTECT experiment of the EXPOSE-E mission on board the International Space Station (ISS), the mutagenic efficiency of space was studied in spores of Bacillus subtilis 168. After 1.5 years' exposure to selected parameters of outer space or simulated martian conditions, the rates of induced mutations to rifampicin resistance (Rif(R)) and sporulation deficiency (Spo(-)) were quantified. In all flight samples, both mutations, Rif(R) and Spo(-), were induced and their rates increased by several orders of magnitude. Extraterrestrial solar UV radiation (>110 nm) as well as simulated martian UV radiation (>200 nm) led to the most pronounced increase (up to nearly 4 orders of magnitude); however, mutations were also induced in flight samples shielded from insolation, which were exposed to the same conditions except solar irradiation. Nucleotide sequencing located the Rif(R) mutations in the rpoB gene encoding the β-subunit of RNA polymerase. Mutations isolated from flight and parallel mission ground reference (MGR) samples were exclusively localized to Cluster I. The 21 Rif(R) mutations isolated from the flight experiment showed all a C to T transition and were all localized to one hotspot: H482Y. In mutants isolated from the MGR, the spectrum was wider with predicted amino acid changes at residues Q469K/L/R, H482D/P/R/Y, and S487L. The data show the unique mutagenic power of space and martian surface conditions as a consequence of DNA injuries induced by solar UV radiation and space vacuum or the low pressure of Mars.