1
|
Torres R, Solsona C, Viñas I, Usall J, Plaza P, Teixidó N. Optimization of packaging and storage conditions of a freeze-dried Pantoea agglomerans
formulation for controlling postharvest diseases in fruit. J Appl Microbiol 2014; 117:173-84. [DOI: 10.1111/jam.12511] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2014] [Revised: 03/24/2014] [Accepted: 03/26/2014] [Indexed: 11/30/2022]
Affiliation(s)
- R. Torres
- IRTA; XaRTA-Postharvest; Lleida Catalonia Spain
| | - C. Solsona
- IRTA; XaRTA-Postharvest; Lleida Catalonia Spain
| | - I. Viñas
- Food Technology Department; Lleida University; XaRTA-Postharvest; Agrotecnio Center; Lleida Catalonia Spain
| | - J. Usall
- IRTA; XaRTA-Postharvest; Lleida Catalonia Spain
| | - P. Plaza
- IRTA; XaRTA-Postharvest; Lleida Catalonia Spain
| | - N. Teixidó
- IRTA; XaRTA-Postharvest; Lleida Catalonia Spain
| |
Collapse
|
2
|
Piskorska M, Soule T, Gosse JL, Milliken C, Flickinger MC, Smith GW, Yeager CM. Preservation of H₂ production activity in nanoporous latex coatings of Rhodopseudomonas palustris CGA009 during dry storage at ambient temperatures. Microb Biotechnol 2013; 6:515-25. [PMID: 23331993 PMCID: PMC3918154 DOI: 10.1111/1751-7915.12032] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Revised: 12/07/2012] [Accepted: 12/08/2012] [Indexed: 11/30/2022] Open
Abstract
To assess the applicability of latex cell coatings as an ‘off-the-shelf’ biocatalyst, the effect of osmoprotectants, temperature, humidity and O2 on preservation of H2 production in Rhodopseudomonas palustris coatings was evaluated. Immediately following latex coating coalescence (24 h) and for up to 2 weeks of dry storage, rehydrated coatings containing different osmoprotectants displayed similar rates of H2 production. Beyond 2 weeks of storage, sorbitol-treated coatings lost all H2 production activity, whereas considerable H2 production was still detected in sucrose- and trehalose-stabilized coatings. The relative humidity level at which the coatings were stored had a significant impact on the recovery and subsequent rates of H2 production. After 4 weeks storage under air at 60% humidity, coatings produced only trace amounts of H2 (0–0.1% headspace accumulation), whereas those stored at < 5% humidity retained 27–53% of their H2 production activity after 8 weeks of storage. When stored in argon at < 5% humidity and room temperature, R. palustris coatings retained full H2 production activity for 3 months, implicating oxidative damage as a key factor limiting coating storage. Overall, the results demonstrate that biocatalytic latex coatings are an attractive cell immobilization platform for preservation of bioactivity in the dry state.
Collapse
Affiliation(s)
- M Piskorska
- University of South Carolina, Aiken, Aiken, SC 29801, USA
| | | | | | | | | | | | | |
Collapse
|
3
|
Improving the storage stability of Bifidobacterium breve in low pH fruit juice. Int J Food Microbiol 2010; 149:106-10. [PMID: 21195496 DOI: 10.1016/j.ijfoodmicro.2010.12.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2010] [Revised: 12/01/2010] [Accepted: 12/02/2010] [Indexed: 11/21/2022]
Abstract
Bifidobacterial food applications are limited since bifidobacteria are sensitive to e.g. acidic conditions prevalent in many food matrices. The aim of the present study was to investigate whether a low pH selection step alone or combined to UV mutagenesis could improve the viability of an acid sensitive Bifidobacterium strain, B. breve 99, in low pH food matrices. Furthermore, the potential of carriers and an oat fibre preparation to further improve the stability was studied. The best performing low pH tolerant variants in the present study were generated by UV-mutagenesis with 70-700μJ/cm(2) followed by incubation in growth medium at pH 4.5. The most promising variants regarding the low pH tolerance showed, in repeated tests with cells grown without pH control, about one Log-value better survival in pH 3.8 fruit juice after one week storage at 4°C compared to wild-type B. breve 99. Cells grown with pH control, PDX formulated and then frozen showed poorer viability in low pH fruit juice than cells grown with no pH control. For frozen concentrates pH 3.8 was too stressful and no or small differences between the variants and the wild-type strain were seen. The differences detected at pH 3.8 with the cells grown without pH control were also seen with the frozen concentrates at pH 4.5. Some improvement in the stability could be achieved by using a combination of trehalose, vitamin C and PDX as a freezing carrier material, whereas a significant improvement in the stability was seen when oat fibre was added into the fruit juice together with the frozen cells. Due to the initial very poor fruit juice tolerance of B. breve 99 the obtained improvement in the stability was not enough for commercial applications. However, the same methods could be applied to initially better performing strains to further improve their stability in the fruit juice.
Collapse
|
4
|
Miyamoto-Shinohara Y, Nozawa F, Sukenobe J, Imaizumi T. Survival of yeasts stored after freeze-drying or liquid-drying. J GEN APPL MICROBIOL 2010; 56:107-19. [DOI: 10.2323/jgam.56.107] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
|
5
|
Kurtmann L, Skibsted LH, Carlsen CU. Browning of freeze-dried probiotic bacteria cultures in relation to loss of viability during storage. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2009; 57:6736-6741. [PMID: 19591471 DOI: 10.1021/jf901044u] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Freeze-dried cultures of Lactobacillus acidophilus (La-5) showed visible brown discoloration even after a short storage at relatively mild conditions (a(w) = 0.22 and 30 degrees C), and the browning processes were found to coincide with bacteria inactivation. It was demonstrated, by using high-pressure treatment for obtaining bacteria samples with different ratios of live/dead bacteria, that death of bacteria is not a prerequisite for the browning processes. Furthermore, it was shown that hydroxymethylfurfural (HMF) (or condensation products of HMF) introduces accelerated viability loss when HMF is added to the freeze-drying medium. Discoloration of bacteria cultures containing only sucrose/maltodextrin or lactose/maltodextrin in the freeze-drying matrices is suggested to be related to various types of nonenzymatic browning reactions, including carbonyl-protein (or carbonyl-DNA) interactions and carbohydrate condensation/polymerization (without involvement of proteins), the latter proceeding at low a(w) following hydrolysis of the peptidoglycan layer in the bacteria cell wall. More than one single type of browning reaction is accordingly concluded to be related to bacteria death, and the loss of viability in freeze-dried bacteria seems to be influenced by oxidation reactions, browning reactions, and the physical instability of the bacteria membrane/cell wall.
Collapse
Affiliation(s)
- Lone Kurtmann
- Department of Food Science, Faculty of Life Sciences, University of Copenhagen, Rolighedsvej 30, DK-1958 Frederiksberg C, Denmark
| | | | | |
Collapse
|
6
|
Investigation of oxidation in freeze-dried membranes using the fluorescent probe C11-BODIPY581/591. Cryobiology 2009; 58:262-7. [DOI: 10.1016/j.cryobiol.2009.01.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
|
7
|
Seetharam C, Soundarajan S, Udas AC, Rao AS, Apte SK. Lyophilized, non-viable, recombinant E. coli cells for cadmium bioprecipitation and recovery. Process Biochem 2009. [DOI: 10.1016/j.procbio.2008.10.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
|
8
|
Santivarangkna C, Kulozik U, Foerst P. Inactivation mechanisms of lactic acid starter cultures preserved by drying processes. J Appl Microbiol 2008; 105:1-13. [DOI: 10.1111/j.1365-2672.2008.03744.x] [Citation(s) in RCA: 173] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
9
|
Miyamoto-Shinohara Y, Sukenobe J, Imaizumi T, Nakahara T. Survival of freeze-dried bacteria. J GEN APPL MICROBIOL 2008; 54:9-24. [DOI: 10.2323/jgam.54.9] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
|
10
|
Higl B, Kurtmann L, Carlsen CU, Ratjen J, Först P, Skibsted LH, Kulozik U, Risbo J. Impact of Water Activity, Temperature, and Physical State on the Storage Stability ofLactobacillus paracaseissp.paracaseiFreeze-Dried in a Lactose Matrix. Biotechnol Prog 2007. [DOI: 10.1002/bp070089d] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
11
|
Guijarro B, Melgarejo P, De Cal A. Effect of stabilizers on the shelf-life of Penicillium frequentans conidia and their efficacy as a biological agent against peach brown rot. Int J Food Microbiol 2006; 113:117-24. [PMID: 16860898 DOI: 10.1016/j.ijfoodmicro.2006.06.024] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2005] [Revised: 04/27/2006] [Accepted: 06/02/2006] [Indexed: 11/15/2022]
Abstract
Stabilizers were added to conidia of Penicillium frequentans at two different points of the production-formulation process to improve shelf-life of conidia stored at different temperatures. Effects were also tested on conidial germination and production. Germination of conidia without additives was 90.2%; sodium chloride, potassium chloride, triton TX100, dimethyl sulphoxide, peroxidase, 0.375% and 0.075% ascorbic acid, 7.5% and 3.75% sucrose, and 7.5% and 3.75% d-sorbitol reduced significantly (P=0.05) conidial germination, while no effect was observed with glucose, lactose, maltose, sodium glutamate, glycerol, peptone, sodium alginate, carboximethylcellulose, Tween 80, and gelatine. Production of P. frequentans conidia in solid-state fermentation without additives was 1.07 conidia x 10(8) g(-1) of dry substrate. The highest tested doses of glucose, lactose, maltose, sodium glutamate, and glycerol enhanced production of P. frequentans, while the lowest tested doses of d-sorbitol and ascorbic acid reduced it. No significant effect was observed with sucrose, peptone, sodium alginate, carboximethylcellulose, gelatine and Tween 80. Conidial germinability after one year of storage at different temperatures was studied in some formulations. It was lower than 18% after 365 days of storage at room temperature in control samples (without any additive), being enhanced when 7.5% glucose, 7.5% glycerol, or 1.5% sodium alginate was added to the substrate in bags before fermentation; or when 7.5% glucose, 7.5% sodium glutamate, or 1.5% sodium alginate was added to conidia before drying. Germinability of conidia produced without any additive and stored at 4 degrees C was significantly higher (38%) than at room temperature, being enhanced when 7.5% glycerol or 1.5% sodium alginate was added to the substrate in bags before fermentation; and when 7.5% glucose, or 1.5% sodium alginate was added to conidia before drying. No effect was observed with the presence or absence of light or high vacuum. Four formulations of P. frequentans conidia reduced disease incidence by more than 55%. The relationship of the disease control with the viability of P. frequentans was discussed.
Collapse
Affiliation(s)
- B Guijarro
- Department of Plant Protection, INIA, Ctra. de La Coruña km. 7, 28040 Madrid, Spain
| | | | | |
Collapse
|
12
|
Miyamoto-Shinohara Y, Sukenobe J, Imaizumi T, Nakahara T. Survival curves for microbial species stored by freeze-drying. Cryobiology 2006; 52:27-32. [PMID: 16271358 DOI: 10.1016/j.cryobiol.2005.09.002] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2005] [Revised: 05/31/2005] [Accepted: 09/08/2005] [Indexed: 11/26/2022]
Abstract
The survival of a variety of species of microorganism following storage for up to 20 years has been analyzed. The organisms were freeze-dried, sealed in ampoules under vacuum (<1 Pa) and stored in the dark at 5 degrees C. The yeast that was tested, Saccharomyces cerevisiae, showed only 8% survival when recovered shortly after freeze-drying, but subsequent loss during storage was the least among all the tested microorganisms. The decrease in the logarithm of survival per year (log survival) was -0.010, which corresponds to a survival rate of 97.7% per year. The Gram-negative bacteria tested, Escherichia coli, Pseudomonas putida, and Enterobacter cloacae, showed 42.6, 33.5, and 50.8% survival shortly after freeze-drying, which was higher than the corresponding survival of S. cerevisiae, but the subsequent loss during storage was greater than S. cerevisiae, the log survival figures being -0.041, -0.058, and -0.073 per year. These values correspond to survival rates of 91.0, 87.5, and 84.5% each year. The Gram-positive bacteria tested, Lactobacillus acidophilus and Enteroccoccus faecium, showed 62.5 and 85.2% survival shortly after freeze-drying, which was even higher than that of the Gram-negative species, and these organisms also showed better survival during storage than Gram-negative bacteria; their log survival rates were -0.018 and -0.016 per year, which corresponded to survival rates of almost 96% per year. Comparison of these results with other published data for different drying conditions suggests that survival during storage is strongly influenced by the degree of vacuum under which the ampoules were sealed. The excellent survival after freeze-drying of each species might be attributable to the high level of desiccation and to sealing under vacuum.
Collapse
Affiliation(s)
- Yukie Miyamoto-Shinohara
- International Patent Organism Depository, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8566, Japan.
| | | | | | | |
Collapse
|
13
|
Larena I, De Cal A, Liñán M, Melgarejo P. Drying of Epicoccum nigrum conidia for obtaining a shelf-stable biological product against brown rot disease. J Appl Microbiol 2003; 94:508-14. [PMID: 12588560 DOI: 10.1046/j.1365-2672.2003.01860.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
AIMS The effects of freeze-drying, spray-drying and fluidized bed-drying on survival of Epicoccum nigrum conidia were compared. METHODS AND RESULTS Viability of E. nigrum conidia (estimated by measuring its germination) was 100% after fluidized bed-drying and freeze-drying, but it was determined that skimmed milk must be added in the case of freeze-drying conidia. Addition of other protectants (Tween-20, peptone, sucrose, glucose, starch and peptone + starch) to skimmed milk before freeze-drying did not improve the conidial viability which was obtained with skimmed milk alone. Glycerol had a negative effect on the lyophilization of E. nigrum conidia. Epicoccum nigrum conidia freeze-dried with skimmed milk, or fluidized bed-dried alone maintained an initial viability for 30 and 90 days, respectively, for storage at room temperature. Epicoccum nigrum conidial viability after spray-drying was lower than 10%. CONCLUSIONS The best method to dry E. nigrum conidia was fluidized bed-drying. Conidia without protectants dried by this method had 100% viability and survived for 90 days at room temperature. SIGNIFICANCE AND IMPACT OF STUDY This paper deals with methods for the potential formulation of a biocontrol agent which is being tested for eventual commercialization.
Collapse
Affiliation(s)
- I Larena
- Department of Plant Protection, INIA, Carretera de La Coruña Km 7, Madrid, Spain
| | | | | | | |
Collapse
|
14
|
Abadias M, Teixidó N, Usall J, Benabarre A, Viñas I. Viability, efficacy, and storage stability of freeze-dried biocontrol agent Candida sake using different protective and rehydration media. J Food Prot 2001; 64:856-61. [PMID: 11403138 DOI: 10.4315/0362-028x-64.6.856] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Viability, efficacy against Penicillium expansum on Golden Delicious apples, and storage stability of freeze-dried Candida sake strain CPA-1 were studied. The effect of several protective agents and rehydration media was investigated in the freeze drying of C. sake. Skimmed milk at 10% concentration was a good rehydration medium for all protectants tested. In general, good viability results were obtained when the same solution was used as a protectant and as a rehydration medium. The best survival was obtained when C. sake cells were protected with 10% lactose + 10% skimmed milk and rehydrated with skimmed milk (85% viability). The potential for biocontrol of the best freeze-dried treatments against P. expansum on apples was compared with that of fresh cells. Freeze-dried treatments at 1 x 10(7) CFU/ml reduced the incidence of decay by 45 to 66%. The best biocontrol effect was obtained with cells that had been freeze dried using 10% lactose + 10% skimmed milk as a protectant and 1% peptone as a rehydration medium, with a 66% reduction in rot incidence. However, in all treatments, the efficacy of freeze-dried cells was significantly lower than fresh cells. The stability of freeze-dried samples decreased during storage and was influenced by storage temperature. In the best treatment, storage of C. sake cells for 60 days at 4 degrees C resulte in final concentrations of 2.5 x 10(8) CFU/ml, which was a 10-fold reduction in relation to the initial starting concentration of cells prior to freeze drying.
Collapse
Affiliation(s)
- M Abadias
- Postharvest Unit, CeRTA, Centre UdL-IRTA, Lleida, Catalonia, Spain.
| | | | | | | | | |
Collapse
|
15
|
Andersen AB, Fog-Petersen MS, Larsen H, Skibsted LH. Storage Stability of Freeze-dried Starter Cultures (Streptococcus thermophilus) as Related to Physical State of Freezing Matrix. Lebensm Wiss Technol 1999. [DOI: 10.1006/fstl.1999.0594] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
|
16
|
Abstract
The removal of cell-bound water through air drying and the addition of water to air-dried cells are forces that have played a pivotal role in the evolution of the prokaryotes. In bacterial cells that have been subjected to air drying, the evaporation of free cytoplasmic water (Vf) can be instantaneous, and an equilibrium between cell-bound water (Vb) and the environmental water (vapor) potential (psi wv) may be achieved rapidly. In the air-dried state some bacteria survive only for seconds whereas others can tolerate desiccation for thousands, perhaps millions, of years. The desiccated (anhydrobiotic) cell is characterized by its singular lack of water--with contents as low as 0.02 g of H2O g (dry weight)-1. At these levels the monolayer coverage by water of macromolecules, including DNA and proteins, is disturbed. As a consequence the mechanisms that confer desiccation tolerance upon air-dried bacteria are markedly different from those, such as the mechanism of preferential exclusion of compatible solutes, that preserve the integrity of salt-, osmotically, and freeze-thaw-stressed cells. Desiccation tolerance reflects a complex array of interactions at the structural, physiological, and molecular levels. Many of the mechanisms remain cryptic, but it is clear that they involve interactions, such as those between proteins and co-solvents, that derive from the unique properties of the water molecule. A water replacement hypothesis accounts for how the nonreducing disaccharides trehalose and sucrose preserve the integrity of membranes and proteins. Nevertheless, we have virtually no insight into the state of the cytoplasm of an air-dried cell. There is no evidence for any obvious adaptations of proteins that can counter the effects of air drying or for the occurrence of any proteins that provide a direct and a tangible contribution to cell stability. Among the prokaryotes that can exist as anhydrobiotic cells, the cyanobacteria have a marked capacity to do so. One form, Nostoc commune, encompasses a number of the features that appear to be critical to the withstanding of a long-term water deficit, including the elaboration of a conspicuous extracellular glycan, synthesis of abundant UV-absorbing pigments, and maintenance of protein stability and structural integrity. There are indications of a growing technology for air-dried cells and enzymes. Paradoxically, desiccation tolerance of bacteria has virtually been ignored for the past quarter century. The present review considers what is known, and what is not known, about desiccation, a phenomenon that impinges upon every facet of the distributions and activities of prokaryotic cells.
Collapse
Affiliation(s)
- M Potts
- Department of Biochemistry and Anaerobic Microbiology, Virginia Polytechnic Institute and State University, Blacksburg 24061
| |
Collapse
|
17
|
Handley BA, Webster AJ. Some factors affecting airborne survival of Pseudomonas fluorescens indoors. THE JOURNAL OF APPLIED BACTERIOLOGY 1993; 75:35-42. [PMID: 8365952 DOI: 10.1111/j.1365-2672.1993.tb03404.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The effect of relative humidity (RH) on the airborne survival of a Pseudomonas fluorescens strain was studied at 20, 40, 60 and 80% RH indoors. The aero-stable spore of Bacillus subtilis subsp. niger, used as a tracer of physical losses was compared with a light scattering particle counter, as there were doubts about the reliability of the spore as tracer. The Rion counter was validated before use and found to give a good estimate of relative physical losses providing spray suspensions contained between 10(7) and 10(9) cfu ml-1 cells and that the humidity was not more than 80% RH. Pseudomonas fluorescens, strain P+S+, suspended in distilled water survived best at mid humidities and least at 80% RH. When suspended in 1% glycerol there was an apparent 'increase' in viability after an initial rapid reduction. This was thought to be due to delay in equilibration of glycerol in the cell membrane after concentration on dehydration. The cells were thought to be unstable and sensitive to the stress of rehydration before equilibration occurred. The findings are discussed in relation to Cox's theories of outer membrane damage on aerosolization.
Collapse
Affiliation(s)
- B A Handley
- Department of Animal Husbandry, University of Bristol, Langford, UK
| | | |
Collapse
|
18
|
Israeli E, Shaffer BT, Hoyt JA, Lighthart B, Ganio LM. Survival differences among freeze-dried genetically engineered and wild-type bacteria. Appl Environ Microbiol 1993; 59:594-8. [PMID: 8434925 PMCID: PMC202149 DOI: 10.1128/aem.59.2.594-598.1993] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Because the death mechanisms of freeze-dried and air-dried bacteria are thought to be similar, freeze-drying was used to investigate the survival differences between potentially airborne genetically engineered microorganisms and their wild types. To this end, engineered strains of Escherichia coli and Pseudomonas syringae were freeze-dried and exposed to air, visible light, or both. The death rates of all engineered strains were significantly higher than those of their parental strains. Light and air exposure were found to increase the death rates of all strains. Application of death rate models to freeze-dried engineered bacteria to be released into the environment is discussed.
Collapse
Affiliation(s)
- E Israeli
- Environmental Research Laboratory, U.S. Environmental Protection Agency, Corvallis, Oregon
| | | | | | | | | |
Collapse
|
19
|
Fuchs P, Kohn A. Changes induced in cell membranes adsorbing animal viruses, bacteriophages, and colicins. Curr Top Microbiol Immunol 1983; 102:57-99. [PMID: 6301761 DOI: 10.1007/978-3-642-68906-2_2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
|
20
|
Wong GH, Steiner BM, Graves SR. Effects of anaerobic and microaerophilic conditions of extraction and incubation on the survival of Treponema pallidum in vitro. Br J Vener Dis 1982; 58:139-42. [PMID: 7044469 PMCID: PMC1046032 DOI: 10.1136/sti.58.3.139] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Treponema pallidum extracted from infected rabbit testes under anaerobic conditions survived longer in vitro than those extracted under aerobic conditions. Anaerobically extracted treponemes were incubated anaerobically for 0, 12, 24, 36, or 48 hours and then exposed to microaerophilic conditions (3% oxygen) for further incubation. Treponemes transferred to microaerophilic conditions after 36 or 48 hours' anaerobic incubation maintained significantly greater viability compared with those kept under constant microaerophilic conditions, although there was no difference after 12 or 24 hours. T pallidum incubated under constant anaerobic conditions, however, usually maintained greater viability than those kept under constant microaerophilic conditions. These results suggest that T pallidum is sensitive to oxygen toxicity both during initial extraction from orchitic rabbit testes and subsequent incubation in vitro. In the latter case, it can be partially protected by a period of anaerobic incubation in vitro, before exposure to microaerophilic conditions.
Collapse
|
21
|
Heckly RJ, Quay J. A brief review of lyophilization damage and repair in bacterial preparations. Cryobiology 1981; 18:592-7. [PMID: 7032851 DOI: 10.1016/0011-2240(81)90127-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
|
22
|
|
23
|
Frölander F, Carlsson J. Bactericidal effect of anaerobic broth exposed to atmospheric oxygen tested on Peptostreptococcus anaerobius. J Clin Microbiol 1977; 6:117-23. [PMID: 893657 PMCID: PMC274716 DOI: 10.1128/jcm.6.2.117-123.1977] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Peptostreptococcus anaerobius strain VPI 4330-1 was used as the test organism in an evaluation of the bactericidal effect of anaerobic broth exposed to air. The test organism, grown under anaerobic conditions in Trypticase soy broth, was diluted in buffered salt solution, and about 2 x 10(4) cells were suspended in 10 ml of an aerated broth. Ninety percent of the cells were killed within 15 min in actinomyces broth and within 50 min in Trypticase soy broth. All cells survived for 2 h in fluid thioglycolate medium. Addition of DABCO [1,4-diazabicyclo (2.2.2) octane] or mannitol to Trypticase soy broth did not influence the death rate of the organism, whereas superoxide dismutase decreased the death rate. Addition of catalase or manganese dioxide to the broth kept all the cells viable for 2 h. Of the three broth media tested, actinomyces broth reduced oxygen at the highest rate and Trypticase soy broth reduced it at the slowest rate. Hydrogen peroxide could be demonstrated in actinomyces broth and in Trypticase soy broth but not in fluid thioglycolate medium. In addition to catalase, manganese dioxide also removed all hydrogen peroxide from Trypticase soy broth, and superoxide dismutase significantly decreased the concentration of hydrogen peroxide in the broth. The results suggest that hydrogen peroxide mediated the toxic effect of atmospheric oxygen in these broth media.
Collapse
|
24
|
Morris JG. Fifth Stenhous-Williams memorial lecture. Oxygen and the obligate anaerobe. THE JOURNAL OF APPLIED BACTERIOLOGY 1976; 40:229-44. [PMID: 181358 DOI: 10.1111/j.1365-2672.1976.tb04171.x] [Citation(s) in RCA: 63] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
|