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Pedraza-Reyes M, Abundiz-Yañez K, Rangel-Mendoza A, Martínez LE, Barajas-Ornelas RC, Cuéllar-Cruz M, Leyva-Sánchez HC, Ayala-García VM, Valenzuela-García LI, Robleto EA. Bacillus subtilis stress-associated mutagenesis and developmental DNA repair. Microbiol Mol Biol Rev 2024:e0015823. [PMID: 38551349 DOI: 10.1128/mmbr.00158-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/04/2024] Open
Abstract
SUMMARYThe metabolic conditions that prevail during bacterial growth have evolved with the faithful operation of repair systems that recognize and eliminate DNA lesions caused by intracellular and exogenous agents. This idea is supported by the low rate of spontaneous mutations (10-9) that occur in replicating cells, maintaining genome integrity. In contrast, when growth and/or replication cease, bacteria frequently process DNA lesions in an error-prone manner. DNA repairs provide cells with the tools needed for maintaining homeostasis during stressful conditions and depend on the developmental context in which repair events occur. Thus, different physiological scenarios can be anticipated. In nutritionally stressed bacteria, different components of the base excision repair pathway may process damaged DNA in an error-prone approach, promoting genetic variability. Interestingly, suppressing the mismatch repair machinery and activating specific DNA glycosylases promote stationary-phase mutations. Current evidence also suggests that in resting cells, coupling repair processes to actively transcribed genes may promote multiple genetic transactions that are advantageous for stressed cells. DNA repair during sporulation is of interest as a model to understand how transcriptional processes influence the formation of mutations in conditions where replication is halted. Current reports indicate that transcriptional coupling repair-dependent and -independent processes operate in differentiating cells to process spontaneous and induced DNA damage and that error-prone synthesis of DNA is involved in these events. These and other noncanonical ways of DNA repair that contribute to mutagenesis, survival, and evolution are reviewed in this manuscript.
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Affiliation(s)
- Mario Pedraza-Reyes
- Department of Biology, Division of Natural and Exact Sciences, University of Guanajuato, Guanajuato, Mexico
| | - Karen Abundiz-Yañez
- Department of Biology, Division of Natural and Exact Sciences, University of Guanajuato, Guanajuato, Mexico
| | - Alejandra Rangel-Mendoza
- Department of Biology, Division of Natural and Exact Sciences, University of Guanajuato, Guanajuato, Mexico
| | - Lissett E Martínez
- Department of Biology, Division of Natural and Exact Sciences, University of Guanajuato, Guanajuato, Mexico
| | - Rocío C Barajas-Ornelas
- Department of Biology, Division of Natural and Exact Sciences, University of Guanajuato, Guanajuato, Mexico
| | - Mayra Cuéllar-Cruz
- Department of Biology, Division of Natural and Exact Sciences, University of Guanajuato, Guanajuato, Mexico
| | | | | | - Luz I Valenzuela-García
- Department of Sustainable Engineering, Advanced Materials Research Center (CIMAV), Arroyo Seco, Durango, Mexico
| | - Eduardo A Robleto
- School of Life Sciences, University of Nevada, Las Vegas, Nevada, USA
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Ichikawa S, Okazaki M, Okamura M, Nishimura N, Miyake H. Rare UV-resistant cells in clonal populations of Escherichia coli. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 2022; 231:112448. [PMID: 35490545 DOI: 10.1016/j.jphotobiol.2022.112448] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 04/11/2022] [Accepted: 04/21/2022] [Indexed: 06/14/2023]
Abstract
Water disinfection is one of the most important applications of ultraviolet light-emitting diodes (UV-LEDs), though bacterial regrowth remains a serious problem. In this study, we showed that UV-resistant cells, though rare, exist in an Escherichia coli clonal population. The UV-resistance of stationary phase cells was higher than that of exponential phase cells. Regrowth cell populations showed identical UV sensitivity before and after UV treatment, indicating that UV resistance is not acquired genetically, but is generated stochastically. The characteristics of these UV-resistant cells are similar to those of non-heritable antibiotic-resistant cells, termed persisters. The induction of persister formation increased the number of viable cells after UV treatment. The toxin-antitoxin system gene hipA (high persistence A) is a key factor in persister cell formation. We observed that hipA was strongly expressed in the stationary phase cells, while regrowth cells after UV treatment lost hipA expression, suggesting that the regrowth cells lost their persistence. Compared to UV batch radiation, we demonstrated that intermittent UV irradiation, which included the induction of regrowth between UV treatments, significantly reduced the number of viable E. coli cells.
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Affiliation(s)
- Shunsuke Ichikawa
- Faculty of Education, Mie University, 1577 Kurimamachiya-cho Tsu, Mie 514-8507, Japan.
| | - Mika Okazaki
- Strategic Planning Office for Regional Revitalization, Mie University, 1577 Kurimamachiya-cho Tsu, Mie 514-8507, Japan
| | - Mina Okamura
- Strategic Planning Office for Regional Revitalization, Mie University, 1577 Kurimamachiya-cho Tsu, Mie 514-8507, Japan
| | - Norihiro Nishimura
- Graduate School of Regional Innovation Studies, Mie University, 1577 Kurimamachiya-cho Tsu, Mie 514-8507, Japan
| | - Hideto Miyake
- Graduate School of Regional Innovation Studies, Mie University, 1577 Kurimamachiya-cho Tsu, Mie 514-8507, Japan
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He Y, Wang Y, Qin C, Xu Y, Cheng K, Xu H, Tian B, Zhao Y, Wang L, Hua Y. Structural and Functional Characterization of a Unique AP Endonuclease From Deinococcus radiodurans. Front Microbiol 2020; 11:1178. [PMID: 33117296 PMCID: PMC7548837 DOI: 10.3389/fmicb.2020.01178] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Accepted: 05/08/2020] [Indexed: 11/13/2022] Open
Abstract
Various endogenous and exogenous agents cause DNA damage, including apurinic/apyrimidinic (AP) sites. Due to their cytotoxic effects, AP sites are usually cleaved by AP endonuclease through the base excision repair (BER) pathway. Deinococcus radiodurans, an extraordinary radiation-resistant bacterium, is known as an ideal model organism for elucidating DNA repair processes. Here, we have investigated a unique AP endonuclease (DrXth) from D. radiodurans and found that it possesses AP endonuclease, 3'-phosphodiesterase, 3'-phosphatase, and 3'-5' exonuclease but has no nucleotide incision repair (NIR) activity. We also found that Mg2+ and Mn2+ were the preferred divalent metals for endonuclease and exonuclease activities, respectively. In addition, DrXth were crystallized and the crystals diffracted to 1.5 Å. Structural and biochemical analyses demonstrated that residue Gly198 is the key residue involved in the substrate DNA binding and cleavage. Deletion of the drxth gene in D. radiodurans caused elevated sensitivity to DNA damage agents and increased spontaneous mutation frequency. Overall, our results indicate that DrXth is an important AP endonuclease involved in BER pathway and functions in conjunction with other DNA repair enzymes to maintain the genome stability.
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Affiliation(s)
- Yuan He
- MOE Key Laboratory of Biosystems Homeostasis and Protection, College of Life Sciences, Institute of Biophysics, Zhejiang University, Hangzhou, China
| | - Yiyi Wang
- MOE Key Laboratory of Biosystems Homeostasis and Protection, College of Life Sciences, Institute of Biophysics, Zhejiang University, Hangzhou, China
| | - Chen Qin
- MOE Key Laboratory of Biosystems Homeostasis and Protection, College of Life Sciences, Institute of Biophysics, Zhejiang University, Hangzhou, China
| | - Ying Xu
- MOE Key Laboratory of Biosystems Homeostasis and Protection, College of Life Sciences, Institute of Biophysics, Zhejiang University, Hangzhou, China
| | - Kaiying Cheng
- MOE Key Laboratory of Biosystems Homeostasis and Protection, College of Life Sciences, Institute of Biophysics, Zhejiang University, Hangzhou, China
| | - Hong Xu
- MOE Key Laboratory of Biosystems Homeostasis and Protection, College of Life Sciences, Institute of Biophysics, Zhejiang University, Hangzhou, China
| | - Bing Tian
- MOE Key Laboratory of Biosystems Homeostasis and Protection, College of Life Sciences, Institute of Biophysics, Zhejiang University, Hangzhou, China
| | - Ye Zhao
- MOE Key Laboratory of Biosystems Homeostasis and Protection, College of Life Sciences, Institute of Biophysics, Zhejiang University, Hangzhou, China
| | - Liangyan Wang
- MOE Key Laboratory of Biosystems Homeostasis and Protection, College of Life Sciences, Institute of Biophysics, Zhejiang University, Hangzhou, China
| | - Yuejin Hua
- MOE Key Laboratory of Biosystems Homeostasis and Protection, College of Life Sciences, Institute of Biophysics, Zhejiang University, Hangzhou, China
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Cortesão M, Fuchs FM, Commichau FM, Eichenberger P, Schuerger AC, Nicholson WL, Setlow P, Moeller R. Bacillus subtilis Spore Resistance to Simulated Mars Surface Conditions. Front Microbiol 2019; 10:333. [PMID: 30863384 PMCID: PMC6399134 DOI: 10.3389/fmicb.2019.00333] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Accepted: 02/08/2019] [Indexed: 11/13/2022] Open
Abstract
In a Mars exploration scenario, knowing if and how highly resistant Bacillus subtilis spores would survive on the Martian surface is crucial to design planetary protection measures and avoid false positives in life-detection experiments. Therefore, in this study a systematic screening was performed to determine whether B. subtilis spores could survive an average day on Mars. For that, spores from two comprehensive sets of isogenic B. subtilis mutant strains, defective in DNA protection or repair genes, were exposed to 24 h of simulated Martian atmospheric environment with or without 8 h of Martian UV radiation [M(+)UV and M(-)UV, respectively]. When exposed to M(+)UV, spore survival was dependent on: (1) core dehydration maintenance, (2) protection of DNA by α/β-type small acid soluble proteins (SASP), and (3) removal and repair of the major UV photoproduct (SP) in spore DNA. In turn, when exposed to M(-)UV, spore survival was mainly dependent on protection by the multilayered spore coat, and DNA double-strand breaks represent the main lesion accumulated. Bacillus subtilis spores were able to survive for at least a limited time in a simulated Martian environment, both with or without solar UV radiation. Moreover, M(-)UV-treated spores exhibited survival rates significantly higher than the M(+)UV-treated spores. This suggests that on a real Martian surface, radiation shielding of spores (e.g., by dust, rocks, or spacecraft surface irregularities) might significantly extend survival rates. Mutagenesis were strongly dependent on the functionality of all structural components with small acid-soluble spore proteins, coat layers and dipicolinic acid as key protectants and efficiency DNA damage removal by AP endonucleases (ExoA and Nfo), non-homologous end joining (NHEJ), mismatch repair (MMR) and error-prone translesion synthesis (TLS). Thus, future efforts should focus on: (1) determining the DNA damage in wild-type spores exposed to M(+/-)UV and (2) assessing spore survival and viability with shielding of spores via Mars regolith and other relevant materials.
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Affiliation(s)
- Marta Cortesão
- Space Microbiology Research Group, Radiation Biology Department, Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany
| | - Felix M Fuchs
- Space Microbiology Research Group, Radiation Biology Department, Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany
| | - Fabian M Commichau
- Department of General Microbiology, Institute for Microbiology and Genetics, University of Göttingen, Göttingen, Germany
| | - Patrick Eichenberger
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY, United States
| | - Andrew C Schuerger
- Department of Plant Pathology, Space Life Sciences Laboratory, University of Florida, Merritt Island, FL, United States
| | - Wayne L Nicholson
- Department of Microbiology and Cell Science, Space Life Sciences Laboratory, University of Florida, Merritt Island, FL, United States
| | - Peter Setlow
- Department of Molecular Biology and Biophysics, University of Connecticut Health Center, Farmington, CT, United States
| | - Ralf Moeller
- Space Microbiology Research Group, Radiation Biology Department, Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany
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Role of DNA Repair and Protective Components in Bacillus subtilis Spore Resistance to Inactivation by 400-nm-Wavelength Blue Light. Appl Environ Microbiol 2018; 84:AEM.01604-18. [PMID: 30054368 DOI: 10.1128/aem.01604-18] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2018] [Accepted: 07/24/2018] [Indexed: 11/20/2022] Open
Abstract
The high intrinsic decontamination resistance of Firmicutes spores is important medically (disease) and commercially (food spoilage). Effective methods of spore eradication would be of considerable interest in the health care and medical product industries, particularly if the decontamination method effectively killed spores while remaining benign to both humans and sensitive equipment. Intense blue light at a ∼400 nm wavelength is one such treatment that has drawn significant interest. This work has determined the resistance of spores to blue light in an extensive panel of Bacillus subtilis strains, including wild-type strains and mutants that (i) lack protective components such as the spore coat and its pigment(s) or the DNA protective α/β-type small, acid-soluble spore proteins (SASP); (ii) have an elevated spore core water content; or (iii) lack enzymes involved in DNA repair, including those for homologous recombination and nonhomologous end joining (HR and NHEJ), apurinic/apyrimidinic endonucleases, nucleotide and base excision repair (NER and BER), translesion synthesis (TLS) by Y-family DNA polymerases, and spore photoproduct (SP) removal by SP lyase (SPL). The most important factors in spore blue light resistance were determined to be spore coats/pigmentation, α/β-type SASP, NER, BER, TLS, and SP repair. A major conclusion from this work is that blue light kills spores by DNA damage, and the results in this work indicate at least some of the specific DNA damage. It appears that high-intensity blue light could be a significant addition to the agents used to kill bacterial spores in applied settings.IMPORTANCE Effective methods of spore inactivation would be of considerable interest in the health care and medical products industries, particularly if the decontamination method effectively killed spores while remaining benign to both humans and sensitive equipment. Intense blue light radiation is one such treatment that has drawn significant interest. In this work, all known spore-protective features, as well as universal and spore-specific DNA repair mechanisms, were tested in a systematic fashion for their contribution to the resistance of spores to blue light radiation.
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Structural comparison of AP endonucleases from the exonuclease III family reveals new amino acid residues in human AP endonuclease 1 that are involved in incision of damaged DNA. Biochimie 2016; 128-129:20-33. [PMID: 27343627 DOI: 10.1016/j.biochi.2016.06.011] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 06/20/2016] [Indexed: 12/21/2022]
Abstract
Oxidatively damaged DNA bases are substrates for two overlapping repair pathways: DNA glycosylase-initiated base excision repair (BER) and apurinic/apyrimidinic (AP) endonuclease-initiated nucleotide incision repair (NIR). In the BER pathway, an AP endonuclease cleaves DNA at AP sites and 3'-blocking moieties generated by DNA glycosylases, whereas in the NIR pathway, the same AP endonuclease incises DNA 5' to an oxidized base. The majority of characterized AP endonucleases possess classic BER activities, and approximately a half of them can also have a NIR activity. At present, the molecular mechanism underlying DNA substrate specificity of AP endonucleases remains unclear mainly due to the absence of a published structure of the enzyme in complex with a damaged base. To identify critical residues involved in the NIR function, we performed biochemical and structural characterization of Bacillus subtilis AP endonuclease ExoA and compared its crystal structure with the structures of other AP endonucleases: Escherichia coli exonuclease III (Xth), human APE1, and archaeal Mth212. We found conserved amino acid residues in the NIR-specific enzymes APE1, Mth212, and ExoA. Four of these positions were studied by means of point mutations in APE1: we applied substitution with the corresponding residue found in NIR-deficient E. coli Xth (Y128H, N174Q, G231S, and T268D). The APE1-T268D mutant showed a drastically decreased NIR activity and an inverted Mg(2+) dependence of the AP site cleavage activity, which is in line with the presence of an aspartic residue at the equivalent position among other known NIR-deficient AP endonucleases. Taken together, these data show that NIR is an evolutionarily conserved function in the Xth family of AP endonucleases.
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Abstract
Spores of various Bacillus and Clostridium species are among the most resistant life forms known. Since the spores of some species are causative agents of much food spoilage, food poisoning, and human disease, and the spores of Bacillus anthracis are a major bioweapon, there is much interest in the mechanisms of spore resistance and how these spores can be killed. This article will discuss the factors involved in spore resistance to agents such as wet and dry heat, desiccation, UV and γ-radiation, enzymes that hydrolyze bacterial cell walls, and a variety of toxic chemicals, including genotoxic agents, oxidizing agents, aldehydes, acid, and alkali. These resistance factors include the outer layers of the spore, such as the thick proteinaceous coat that detoxifies reactive chemicals; the relatively impermeable inner spore membrane that restricts access of toxic chemicals to the spore core containing the spore's DNA and most enzymes; the low water content and high level of dipicolinic acid in the spore core that protect core macromolecules from the effects of heat and desiccation; the saturation of spore DNA with a novel group of proteins that protect the DNA against heat, genotoxic chemicals, and radiation; and the repair of radiation damage to DNA when spores germinate and return to life. Despite their extreme resistance, spores can be killed, including by damage to DNA, crucial spore proteins, the spore's inner membrane, and one or more components of the spore germination apparatus.
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Interaction of apurinic/apyrimidinic endonucleases Nfo and ExoA with the DNA integrity scanning protein DisA in the processing of oxidative DNA damage during Bacillus subtilis spore outgrowth. J Bacteriol 2013; 196:568-78. [PMID: 24244006 DOI: 10.1128/jb.01259-13] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Oxidative stress-induced damage, including 8-oxo-guanine and apurinic/apyrimidinic (AP) DNA lesions, were detected in dormant and outgrowing Bacillus subtilis spores lacking the AP endonucleases Nfo and ExoA. Spores of the Δnfo exoA strain exhibited slightly slowed germination and greatly slowed outgrowth that drastically slowed the spores' return to vegetative growth. A null mutation in the disA gene, encoding a DNA integrity scanning protein (DisA), suppressed this phenotype, as spores lacking Nfo, ExoA, and DisA exhibited germination and outgrowth kinetics very similar to those of wild-type spores. Overexpression of DisA also restored the slow germination and outgrowth phenotype to nfo exoA disA spores. A disA-lacZ fusion was expressed during sporulation but not in the forespore compartment. However, disA-lacZ was expressed during spore germination/outgrowth, as was a DisA-green fluorescent protein (GFP) fusion protein. Fluorescence microscopy revealed that, as previously shown in sporulating cells, DisA-GFP formed discrete globular foci that colocalized with the nucleoid of germinating and outgrowing spores and remained located primarily in a single cell during early vegetative growth. Finally, the slow-outgrowth phenotype of nfo exoA spores was accompanied by a delay in DNA synthesis to repair AP and 8-oxo-guanine lesions, and these effects were suppressed following disA disruption. We postulate that a DisA-dependent checkpoint arrests DNA replication during B. subtilis spore outgrowth until the germinating spore's genome is free of damage.
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Moeller R, Reitz G, Li Z, Klein S, Nicholson WL. Multifactorial resistance of Bacillus subtilis spores to high-energy proton radiation: role of spore structural components and the homologous recombination and non-homologous end joining DNA repair pathways. ASTROBIOLOGY 2012; 12:1069-77. [PMID: 23088412 PMCID: PMC3491616 DOI: 10.1089/ast.2012.0890] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
The space environment contains high-energy charged particles (e.g., protons, neutrons, electrons, α-particles, heavy ions) emitted by the Sun and galactic sources or trapped in the radiation belts. Protons constitute the majority (87%) of high-energy charged particles. Spores of Bacillus species are one of the model systems used for astro- and radiobiological studies. In this study, spores of different Bacillus subtilis strains were used to study the effects of high energetic proton irradiation on spore survival. Spores of the wild-type B. subtilis strain [mutants deficient in the homologous recombination (HR) and non-homologous end joining (NHEJ) DNA repair pathways and mutants deficient in various spore structural components such as dipicolinic acid (DPA), α/β-type small, acid-soluble spore protein (SASP) formation, spore coats, pigmentation, or spore core water content] were irradiated as air-dried multilayers on spacecraft-qualified aluminum coupons with 218 MeV protons [with a linear energy transfer (LET) of 0.4 keV/μm] to various final doses up to 2500 Gy. Spores deficient in NHEJ- and HR-mediated DNA repair were significantly more sensitive to proton radiation than wild-type spores, indicating that both HR and NHEJ DNA repair pathways are needed for spore survival. Spores lacking DPA, α/β-type SASP, or with increased core water content were also significantly more sensitive to proton radiation, whereas the resistance of spores lacking pigmentation or spore coats was essentially identical to that of the wild-type spores. Our results indicate that α/β-type SASP, core water content, and DPA play an important role in spore resistance to high-energy proton irradiation, suggesting their essential function as radioprotectants of the spore interior.
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Affiliation(s)
- Ralf Moeller
- German Aerospace Center (DLR e.V.), Institute of Aerospace Medicine, Radiation Biology Department, Cologne, Germany.
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Protective role of spore structural components in determining Bacillus subtilis spore resistance to simulated mars surface conditions. Appl Environ Microbiol 2012; 78:8849-53. [PMID: 23064347 DOI: 10.1128/aem.02527-12] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Spores of wild-type and mutant Bacillus subtilis strains lacking various structural components were exposed to simulated Martian atmospheric and UV irradiation conditions. Spore survival and mutagenesis were strongly dependent on the functionality of all of the structural components, with small acid-soluble spore proteins, coat layers, and dipicolinic acid as key protectants.
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Moeller R, Vlašić I, Reitz G, Nicholson WL. Role of altered rpoB alleles in Bacillus subtilis sporulation and spore resistance to heat, hydrogen peroxide, formaldehyde, and glutaraldehyde. Arch Microbiol 2012; 194:759-67. [PMID: 22484477 DOI: 10.1007/s00203-012-0811-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2011] [Revised: 03/21/2012] [Accepted: 03/23/2012] [Indexed: 11/29/2022]
Abstract
Mutations in the RNA polymerase β-subunit gene rpoB causing resistance to rifampicin (Rif(R)) in Bacillus subtilis were previously shown to lead to alterations in the expression of a number of global phenotypes known to be under transcriptional control. To better understand the influence of rpoB mutations on sporulation and spore resistance to heat and chemicals, cells and spores of the wild-type and twelve distinct congenic Rif(R) mutant strains of B. subtilis were tested. Different levels of glucose catabolite repression during sporulation and spore resistance to heat and chemicals were observed in the Rif(R) mutants, indicating the important role played by the RNA polymerase β-subunit, not only in the catalytic aspect of transcription, but also in the initiation of sporulation and in the spore resistance properties of B. subtilis.
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Affiliation(s)
- Ralf Moeller
- Institute of Aerospace Medicine, German Aerospace Center, Linder Hoehe, 51147 Cologne, Germany.
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A comparative study of the bactericidal activity and daily disinfection housekeeping surfaces by a new portable pulsed UV radiation device. Curr Microbiol 2012; 64:581-7. [PMID: 22447288 DOI: 10.1007/s00284-012-0110-y] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Accepted: 03/05/2012] [Indexed: 10/28/2022]
Abstract
Daily cleaning and disinfecting of non-critical surfaces in the patient-care areas are known to reduce the occurrence of health care-associated infections. However, the conventional means for decontamination of housekeeping surfaces of sites of frequent hand contact such as manual disinfection using ethanol wipes are laborious and time-consuming in daily practice. This study evaluated a newly developed portable pulsed ultraviolet (UV) radiation device for its bactericidal activity in comparison with continuous UV-C, and investigated its effect on the labor burden when implemented in a hospital ward. Pseudomonas aeruginosa, Multidrug-resistant P. aeruginosa, Escherichia coli, Acinetobacter baumannii, Amikacin and Ciprofloxacin-resistant A. baumannii, Staphylococcus aureus, Methicillin-resistant S. aureus and Bacillus cereus were irradiated with pulsed UV or continuous UV-C. Pulsed UV and continuous UV-C required 5 and 30 s of irradiation, respectively, to attain bactericidal activity with more than 2Log growth inhibition of all the species. The use of pulsed UV in daily disinfection of housekeeping surfaces reduced the working hours by half in comparison to manual disinfection using ethanol wipes. The new portable pulsed UV radiation device was proven to have a bactericidal activity against critical nosocomial bacteria, including antimicrobial-resistant bacteria after short irradiation, and was thus found to be practical as a method for disinfecting housekeeping surfaces and decreasing the labor burden.
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