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1.
Gisela S. Alvarez María L. Foglia Guillermo J. Copello Martín F. Desimone Luis E. Diaz 《Applied microbiology and biotechnology》2009,82(4):639-646
Immobilized bacteria are being extensively used for metabolite production, biocatalysts, and biosensor construction. However,
long-term viability and metabolic activity of entrapped bacteria is affected by several conditions such as their physiological
state, the presence of high-osmolarity environments, porous structure and shrinkage of the matrix. The aim of this work was
to evaluate the effect of various parameters on bacteria immobilized in sol–gel-derived silica matrices. With this purpose,
we evaluated the stress of immobilization over bacteria cultures obtained from different growing states, the effect of cell
density and bacteria capability to proliferate inside matrices. Best results to attain longer preservation times were obtained
when we immobilized suspensions with an optimized bacterial number of 1 × 107 cfu/gel in the presence of LB medium using aqueous silica precursors. Furthermore, the impact of osmotic stress with the
subsequent intracellular trehalose accumulation and the addition of osmolites were investigated. Shorter preservation times
were found for bacteria immobilized in the presence of osmolites while trehalose accumulation in stressed cells did not produce
changes on entrapped bacteria viability. Finally, nutrient addition in silica matrices was studied indicating that the presence
of a carbon source without the simultaneous addition of nitrogen was detrimental for immobilized E. coli. However, when both carbon and nitrogen sources were present, bacteria were able to survive longer periods of time. 相似文献
2.
【目的】甲烷氧化混合菌是自然界中吸收甲烷的关键微生物,在甲烷氧化混合菌的研究和应用中,首先要解决其长期稳定保藏的问题,保藏方法应能有效保持菌群结构和功能的完整性、稳定性。【方法】以从煤矿土壤富集得到的两种结构稳定的甲烷氧化混合菌为实验体系,研究对比了冷藏法、低温冷冻法、石蜡油冷冻法、甘油冷冻法4种保藏方法,考察保藏前后混合菌的生长状况、MMO活性、菌群结构等。【结果】保藏6个月后,除甘油冷冻法以外,经其它3种方法保藏的混合菌,都具有与保藏前相当的细胞密度、甲烷氧化能力、MMO酶活以及传代稳定性,且DGGE图谱显示保藏前后的菌群结构变化不大。【结论】这3种保藏方法都可以有效的保持甲烷氧化混合菌功能和菌群结构的稳定性。 相似文献
3.
【目的】获得高活菌恶臭假单胞菌菌粉,提高菌体干燥及保藏存活率。【方法】选用冷风干燥法制备活菌粉,并优化吸附载体与保护剂。【结果】冷风干燥制备恶臭假单胞菌菌粉干燥存活率普遍达到65%以上,显著优于喷雾干燥(24%);对载体与保护剂进行正交试验优化,确定了载体为混合的硅藻土和碱处理玉米芯粉,混合比为1:2,保护剂(质量比)为甘露醇7%、谷氨酸钠5%、甘油1%,制得菌粉活菌数为1.03×1011 CFU/g,室温保藏30 d和4 °C保藏60 d存活率分别达到40.54%和71.67%。【结论】冷风干燥温度相对较低(10?40 °C),对菌体损伤小,碱处理玉米芯粉、甘露醇和谷氨酸钠是提高菌粉保藏存活率的重要因子,此法克服了革兰氏阴性菌菌粉不易制备和不耐保藏的瓶颈。 相似文献
4.
Sorokulova I Watt J Olsen E Globa L Moore T Barbaree J Vodyanoy V 《Journal of microbiological methods》2012,88(1):140-146
Stability of microbial cultures during sampling and storage is a vital issue in various fields of medicine, biotechnology, food science, and forensics. We have developed a unique bacterial preservation process involving a non-toxic, water-soluble acacia gum polymer that eliminates the need for refrigerated storage of samples.The main goal of this study is to characterize the efficacy of acacia gum polymer for preservation of pathogenic bacteria (Bacillus anthracis and methicillin-resistant Staphylococcus aureus—MRSA) on different materials, used for swabbing and filtration: cotton, wool, polyester, rayon, charcoal cloth, and Whatman paper.Acacia gum polymer used for preservation of two pathogens has been shown to significantly protect bacteria during dehydration and storage in all tested samples at the range of temperatures (5-45 °C for MRSA and 40-90 °C for B. anthracis). Our results showed higher recovery as well as higher viability during the storage of both bacteria in all materials with acacia gum. Addition of acacia gum polymer to swabbing materials or filters will increase efficacy of sample collection and identification of pathogenic bacteria from locations such as hospitals or the environment. Proposed approach can also be used for long-term storage of culture collections, since acacia gum contributes to viability and stability of bacterial cultures. 相似文献
5.
The results of recent (10–12 years) research in the functions of two-gene chromosomal modules are considered and generalized.
One of the genes encodes a toxin protein; the product of the other gene is an antitoxin protein. In the course of balanced
bacterial growth, the toxin is constantly neutralized by the antitoxin; however, certain metabolic changes (amino acid starvation,
etc.) disturb the balance and then the toxin “poisons” the cell (in most cases, by destroying mRNA). As a result, bacterial
growth ceases. In accordance with one group of the data, long-term inhibition of growth of most cells results in their programmed
death and destruction, corresponding to apoptosis; this allows a minor part of the population to survive due to an additional
nutrient source. The results of other works show that growth inhibition is mostly reversible and the functions of the relevant
gene modules are restricted to the regulation of cell metabolism, i.e., transition of bacteria to the hypometabolic state.
There is also a compromise point of view. The possibilities of biotechnological applications for “toxin-antitoxin” systems
are discussed. 相似文献
6.
Misawa N Nodate M Otomatsu T Shimizu K Kaido C Kikuta M Ideno A Ikenaga H Ogawa J Shimizu S Shindo K 《Applied microbiology and biotechnology》2011,92(1):147-157
Deposit of useful microorganisms in culture collections requires long-term preservation and successful reactivation techniques.
The goal of this study was to develop a simple preservation protocol for the long-term storage and reactivation of the anammox
biomass. To achieve this, anammox biomass was frozen or lyophilized at two different freezing temperatures (−60°C and in liquid
nitrogen (−200°C)) in skim milk media (with and without glycerol), and the reactivation of anammox activity was monitored
after a 4-month storage period. Of the different preservation treatments tested, only anammox biomass preserved via freezing
in liquid nitrogen followed by lyophilization in skim milk media without glycerol achieved stoichiometric ratios for the anammox
reaction similar to the biomass in both the parent bioreactor and in the freshly harvested control treatment. A freezing temperature
of −60°C alone, or in conjunction with lyophilization, resulted in the partial recovery of the anammox bacteria, with an equal
mixture of anammox and nitrifying bacteria in the reactivated biomass. To our knowledge, this is the first report of the successful
reactivation of anammox biomass preserved via sub-zero freezing and/or lyophilization. The simple preservation protocol developed
from this study could be beneficial to accelerate the integration of anammox-based processes into current treatment systems
through a highly efficient starting anammox biomass. 相似文献
7.
Regulation of bacterial assemblages in oligotrophic plankton systems: results from experimental and empirical approaches 总被引:2,自引:0,他引:2
Bacteria are relevant members of planktonic food webs, both in terms of biomass and production share. The assessment and comprehension
of the factors that control bacterial abundance and production are, thus, necessary to understand how carbon and nutrients
circulate in planktonic food webs. It is commonly believed that bacterial abundance, activity and production are either determined
by the available nutrient levels (‘bottom-up’ control) or by the effect of predators (‘top-down’). These factors have also
been shown to regulate the internal structure (the physiological and phylogenetic structure) of the bacterioplankton black
box. We present here different empirical and experimental ways in which the factors that control bacterial communities are
assessed, among them, the direct comparison of the rates of bacterial growth and losses to grazing. Application of several
of these methods to open ocean data suggests that bacteria are regulated by resources at the largest scales of analysis, but
that this overall regulation is strongly modulated by predators in all types of systems. In the most oligotrophic environments,
bacterial abundance and growth are regulated by predators, while in the richest environments it is bacterial (phylogenetic,
size, activity) community composition that is most affected by protist predators, while abundance can be influenced by metazoans.
Because changes in bacterial community composition require that bacteria have enough nutrient supply, the overall effect of
these regulations is that bacterial growth appears to be top-down regulated in the most nutrient-poor environments and bottom-up
regulated in the richer ones.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
8.
9.
A technique for long-term preservation of phytopathogenic bacteria is described. It is based on selective multiplication of the bacterial pathogen in host tissue, disinfection of leaf surfaces to reduce contamination, lyophilization of leaves, and storage under dry conditions at - 80°C. With this technique, the pathogenicity of large numbers of the pathogens Pseudomonas syringae pv. tomato and Xanthomonas campestris pv. vesicatoria was maintained for 4 years. 相似文献
10.
Heylen K Ettwig K Hu Z Jetten M Kartal B 《Applied and environmental microbiology》2012,78(8):3010-3013
A quick and simple protocol for long-term cryopreservation of anaerobic ammonium-oxidizing bacteria (anammox bacteria) was developed. After 29 weeks of preservation at -80°C, activity recovery for all tested cultures under at least one of the applied sets of preservation conditions was observed. Growth recovery was also demonstrated for a single-cell culture of "Candidatus Kuenenia stuttgartiensis." 相似文献
11.
Wen-Lu Bi Chen Pan Xin-Yi Hao Zhen-Hua Cui Mafatlal M. Kher Zvjezdana Marković Qiao-Chun Wang Jaime A. Teixeira da Silva 《In vitro cellular & developmental biology. Plant》2017,53(5):449-460
Grapevine (Vitis genus) is one of the economically most important fruits worldwide. Some species and cultivars are rare and have only a few vines, but represent national heritages with a strong need for preservation. Field collections are labor intensive, and expensive to maintain, and are exposed to natural disasters. In addition, infection with pathogens, especially viruses, is common in grapevine because of vegetative propagation, which is conventionally used for this genus. Cryopreservation provides an alternative and ideal means for the long-term preservation of Vitis germplasm, which can be used as a backup to field collections for important autochthonous cultivars or only as cryo-banks for rare, native cultivars that are worthy of preservation. Cryotherapy, based on cryopreservation protocols, provides an efficient method for the eradication of grapevine viruses. This review provides comprehensive and updated information on cryopreservation for long-term preservation of genetic resources and cryotherapy for virus eradication in Vitis. Additional research in grapevine cryopreservation and cryotherapy is needed. 相似文献
12.
寺河矿煤地质产甲烷微生物菌群的保藏和产甲烷性能 总被引:1,自引:0,他引:1
【背景】煤地质产甲烷微生物菌群可以代谢煤基质产生甲烷,对于实现煤层气资源的再利用具有重要意义。【目的】检测产甲烷菌群在保藏过程中群落结构的动态变化以及在产气实验中甲烷气的生成情况,以验证保藏方法的可行性,同时为煤层气的微生物增产奠定基础。【方法】分别于不同温度条件下比较3种菌种保藏方法,即甘油/L-半胱氨酸法、富营养法和煤基-基础盐法。通过产气实验检测不同保藏条件下产甲烷菌群的活力。同时,采用454高通量测序技术测定16S r RNA基因序列,分析25°C条件下煤基-基础盐菌种保藏过程中微生物群落结构的变化。【结果】比较了9组菌种保藏方法,发现菌种最佳保藏条件为25°C的煤基-基础盐保藏。在该条件下保藏的产甲烷菌群活性最高,甲烷生成量最大。以无烟煤为碳源进行产气实验时甲烷生成量为12%-25%,而以褐煤为碳源时甲烷生成量可达24%-73%。在25°C的煤基-基础盐菌种保藏条件下,保藏初期细菌的主要优势菌为假单胞菌属(Pseudomonas),而古菌的主要优势菌为甲烷八叠球菌属(Methanosarcina)。随着保藏时间的增加,细菌的群落结构变化显著,发酵细菌及产氢产乙酸细菌成为优势细菌,古菌的群落结构则相对稳定。【结论】菌种保藏的最佳条件为25°C的煤基-基础盐,保藏的产甲烷菌群能长期维持在较高的活性状态,具有较好的产甲烷能力。 相似文献
13.
Paulo Luísa Ferreira Susana Gallardo Eugenia Queiroz João António Domingues Fernanda 《World journal of microbiology & biotechnology》2010,26(8):1533-1538
Resveratrol (3,4′,5-trihydroxistilbene) is a phytoalexin commonly found in food and drinks, which is thought to possess antimicrobial
activity. These effects together with its well known antioxidant properties are beneficial for the prevention of some diseases,
e.g. cancer. In this study we have verified that resveratrol has antibacterial activity against all tested Gram-positive bacteria
using both the disk diffusion and broth microdilution methods. Time kill assays of this compound against Gram-positive bacteria
showed that its effects on the growth of bacterial cells were due to bacteriostatic action. The addition of resveratrol has
allowed the identification of changes in cell morphology and DNA contents, which have been assessed through microscopic analysis
and flow cytometry; this suggests that the cell cycle is affected by resveratrol. This study indicates that this compound
may have potential as a natural antibacterial agent for both food preservation and medicinal use. 相似文献
14.
Bacterial degradation is an ecosystem service that offers a promising method for the remediation of contaminated soils. To
assess the dynamics and efficiency of bacterial degradation, reliable microbial simulation models, along with the relevant
processes, are required. We present an approach aimed at improving reliability by studying the relevance and implications
of an important concept from theoretical ecology in the context of a bacterial system: conditional dispersal denoting that
the dispersal strategy depends on environmental conditions. Different dispersal strategies, which either incorporate or neglect
this concept, are implemented in a bacterial model and results are compared to data obtained from laboratory experiments with
Pseudomonas putida colonies growing on glucose agar. Our results show that, with respect to the condition of resource uptake, the model’s correspondence
to experimental data is significantly higher for conditional than for unconditional bacterial dispersal. In particular, these
results support the hypothesis that bacteria disperse less when resources are abundant. We also show that the dispersal strategy
has a considerable impact on model predictions for bacterial degradation of resources: disregarding conditional bacterial
dispersal can lead to overestimations when assessing the performance of this ecosystem service. 相似文献
15.
Annadurai Senthilkumar Krishnan Kannathasan Venugopalan Venkatesalu 《World journal of microbiology & biotechnology》2009,25(7):1297-1300
The antibacterial activity of the leaf essential oil of Blumea mollis was assayed against 14 clinically isolated bacterial strains on Muller–Hinton Agar medium and Muller–Hinton Agar medium with
5% sheep blood. The essential oil had promising antibacterial activity against all the bacterial strains tested. The highest
mean zone of inhibition and lowest values of minimum inhibitory concentration were recorded against methicillin-resistant
Staphylococcus aureus followed by beta hemolytic Streptococcus pyogenes. The Gram-positive bacteria were more sensitive than Gram-negative bacteria. Among the bacterial strains tested, Psudomonas aeruginosa was resistant to the essential oil. The results of the present study suggest that the essential oil of B. mollis is one of the new medicinal resources as an antibacterial agent against the bacterial strains tested. 相似文献
16.
In order to get some basic information for the development of a long-term preservation method by freezing at moderately low temperatures, the viability of 259 strains belonging to 32 genera and 135 species was measured. Cells were suspended in 10% glycerol and stored at ?53 °C for 16 months. About 93%, 88%, and 74% of aerobic bacteria gave viable cell counts higher than 105/ml, 106/ml, and 107/ml, respectively. About 10% of gram-positives and 3% of gram-negatives gave viable cell counts lower than 105/ml. There seemed to be some species—and genus—specificity with respect to viability after frozen storage and liquid paraffin-seal storage. Strains of coryneform bacteria, genera of the family Enterobacteriaceae, and the genus Pseudomonas were generally resistant. Pseudomonas putrefaciens proved to be specifically sensitive. Lactic acid bacteria were subject to sublethal injury, requiring special recovery media. Psychrophilic bacteria were very susceptible to frozen storage. All the tested strains of acetic acid bacteria survived frozen storage well both in 10% glycerol and in 10% honey at ?28 °C for 4.5 years. Honey proved to be a better adjuvant for frozen storage than glycerol. It was suggested from the results that for many kinds of bacteria, long-term preservation by freezing at moderately low temperatures might be possible when appropriate procedures are applied. 相似文献
17.
M. Calomme J. Hu K. Van Den Branden D. A. Vanden Berghe 《Biological trace element research》1995,47(1-3):379-383
Lactic acid bacteria are nonpathogenic bacteria commonly used in food processing. An evaluation was made of the capacity to
concentrate selenium in species of Lactobacillus. A selenium concentration of 1 μg/mL in the culture medium yielded in a bacterial
content of 400 μg/g dry biomass. Dialysis and TCA precipitation experiments of a native intracellular extract proved that
at least 80% of the total selenium is associated with organic molecules. Seleno-cysteine was identified as the only seleno-amino
acid present in the intracellular selenoproteins. This study shows that species of the lactic acid bacteria are able to concentrate
selenium intracellular as seleno-cysteine, which could be applied in supplementation studies. 相似文献
18.
The greater bulk of soil nitrogen is immobilized in chitinous cell walls of fungi. Mycophagous soil mites participate in chitin
decomposition and, hence, in the subsequent mobilization of nitrogen. The source of the chitinolytic enzymes was searched
in this study. A multimethodical approach was designed for these studies. Histology, plating and identification of bacteria
from mite homogenate and, finally, homogenate and bacterial treatment of the soil fungi were applied. Here the presence and
activity of chitinolytic bacteria inside mycophagous mites are reported. These bacteria form an extraintestinal group within
the mite’s body and pass their enzymes into the mite’s gut. Our results demonstrate that true mycophagous mites, defined by
their ability to digest chitin (i.e. the fungal cell wall), achieve this through internal “cooperation” with chitinolytic
bacteria that provide the necessary chitinolytic enzymes. The nitrogen from chitin is thus made available to other soil organisms
and plants. 相似文献
19.
This work is concerned with the role of alkylhydroxybenzenes (AHBs), chemical analogs of the autoregulatory microbial d
1 factors, on the development of the stress response of bacterial cells to UV irradiation, including SOS system induction,
preservation of cell viability, and S → R phase transitions of the Escherichia coli test strain with the bioluminescence genes cloned under the control of the recA gene promoter. UV irradiation, a natural stress factor, and an increase in AHB concentrations were found to elicit uniform
responses in bacteria, indicating that AHBs function as alarmones, i.e., alarm signals. It was revealed that preincubating
bacteria with alkylhydroxybenzenes considerably enhanced their viability upon irradiation with lethal UV doses; this was accompanied
by a relative decrease in the SOS response activity and a concomitant increase in the frequency of phase transitions. The
efficiency of the protective action of AHBs increased with an increase in their hydrophobicity degree. The probable mechanism
of the protective effect of AHBs is discussed, based on their capacity for the interaction with biopolymers, which results
in changing their structural organization and conferring resistance to a broad spectrum of stress factors. Such a “passive”
protective mechanism reduces the susceptibility of DNA to UV irradiation, causing a decrease in the parameters related to
the SOS system induction that is responsible for the “active” protective mechanism in bacterial cells. As a result, viability
retention under the lethal influence of UV irradiation is possible at minimal values of repair activity and is accompanied
by an increase in the phenotypic variability of the surviving part of a bacterial population. 相似文献
20.
J.E. Moore A.B. Shaw T. Stanley M.J. Crowe & J.S. Elborn 《Letters in applied microbiology》2001,33(1):82-83
Long-term preservation methods are important in the maintenance of bacteria for downstream research applications. Most clinical laboratories have only limited resources for archiving isolates and therefore require cost-effective and simple methods. An effective and cheap storage method using debrinated blood and maintenance at -80 degrees C is described. 相似文献