Survival Of Bacterial Pathogens Research Articles

Changes in the population and functional profile of bacteria and fungi in the rhizosphere of Suaeda salsa is driven by invasion of Spartina alterniflora

Changes in rhizosphere microbial populations and their functions in response to Spartina alterniflora root invasion could potentially reveal part of the mechanism of Suaeda salsa degradation. In this study, rhizosphere soils were collected from regions where S. alterniflora (SA) and S. salsa (SS) grew independently as well as rhizosphere soil from mixed growth regions (namely MSA and MSS) before applying high-throughput sequencing technology to study the characteristics of microbial communities. The results showed that the physicochemical properties of the rhizosphere soils were different between the groups of samples. However, based on the multi-factor PERMANOVA analysis, only EC and NO3−-N were found to significantly influence the microbial communities’ composition. Furthermore, α diversity indices and β diversity analyses revealed that the diversity and structure of rhizosphere microbial community changed in varying degrees after invasion. Compared with SS, the most abundant bacteria phylum namely Tenericutes, Firmicutes, Proteobacteria and Actinobacteria in MSS were identified as major species that increased significantly in abundance in response to S. alterniflora root invasion, while the composition of fungal community did not change. Furthermore, PICRUSt analysis revealed that the higher abundance of signal transduction, membrane transport, cell motility and certain disease-related functional pathways of MSA and MSS could be conducive to the colonization and survival of bacterial pathogens. Additionally, the analysis of the FUNGuild database confirmed that a higher proportion of pathotroph and pathogen. This could very likely cause S. salsa to be more susceptible to soil pathogenic fungi in mixed growth region. In contrast, the increase of the saprotroph-symbiotroph could be beneficial for the colonization and expansion of S. alterniflora. This study provides a new perspective for elucidating the driving mechanism by microorganisms behind S. salsa’s degradation following S. alterniflora’s invasion.

Role of ATP-Small Heat Shock Protein Interaction in Human Diseases.

Adenosine triphosphate (ATP) is an important fuel of life for humans and Mycobacterium species. Its potential role in modulating cellular functions and implications in systemic, pulmonary, and ocular diseases is well studied. Plasma ATP has been used as a diagnostic and prognostic biomarker owing to its close association with disease’s progression. Several stresses induce altered ATP generation, causing disorders and illnesses. Small heat shock proteins (sHSPs) are dynamic oligomers that are dominantly β-sheet in nature. Some important functions that they exhibit include preventing protein aggregation, enabling protein refolding, conferring thermotolerance to cells, and exhibiting anti-apoptotic functions. Expression and functions of sHSPs in humans are closely associated with several diseases like cataracts, cardiovascular diseases, renal diseases, cancer, etc. Additionally, there are some mycobacterial sHSPs like Mycobacterium leprae HSP18 and Mycobacterium tuberculosis HSP16.3, whose molecular chaperone functions are implicated in the growth and survival of pathogens in host species. As both ATP and sHSPs, remain closely associated with several human diseases and survival of bacterial pathogens in the host, therefore substantial research has been conducted to elucidate ATP-sHSP interaction. In this mini review, the impact of ATP on the structure and function of human and mycobacterial sHSPs is discussed. Additionally, how such interactions can influence the onset of several human diseases is also discussed.

Effect of Lactoperoxidase Enzyme System in Improving Shelflife of Raw Milk from Dairy Farms in Khartoum State, Sudan

Lactoperoxidase enzyme (LP) is a natural component in milk with broad spectrum of antimicrobial activity applications in in vivo and in vitro. LP system (LPS) was developed to eliminate the growth of bacterial pathogens and augment the shelf life of raw milk. The aim of this study was to evaluate the effect of activation of LPS on the growth and survival of bacterial pathogens and preserving raw milk quality. A checklist was developed and filled in ten farms at the time of milking to detect the hygienic measures in these farms. Two liters of milk were collected in sterile containers and warmed to 37°C/15min. LPS was activated by dissolving 40mg and 30mg of sodium thiocyanate and sodium percarbonate, respectively, in one liter of milk and followed by thorough mixing. 50ml from this liter of milk was added to two new containers and designated as group B and C. Moreover, group C was supplied with E. coli (106-107 cfu/ml). While milk in group D, LPS was not activated, instead milk was only supplied with E. coli (106-107 cfu/ml). Group A was considered as the control group (neither activated nor supplied with Escherichia coli). Tenfold serial dilution was performed to determine the bacterial total viable count (TVC) and milk clotting time (per seconds) in each group for 2, 4, 6, 8 and 10 hrs. The TVC and the milk clotting time in each group were statistically expressed as pairs between the groups (A versus B; C versus D) with significance probability of P≤0.05. The checklist analysis reflected the bad hygiene measures in the dairy farms. For TVC, in 2hrs incubation; no significant difference was observed between group A versus group B. While group C versus group D showed high significant difference. After 4hrs incubation, TVC showed prominent significance difference between the control compared to group B. While group C versus group D showed no statistical significance differences. At 6hrs time period, a significant difference was observed between the compared groups. However, no significance differences were observed between the groups after 8hrs and 10hrs of incubation. For clotting time, in 2hrs incubation, a significant difference between the compared groups was observed. After 4hrs incubation, a significant difference between the control compared to group B was prominent, while group C versus group D showed no statistical differences in clotting time. However, no significant differences were observed between the groups after 6, 8 and 10hrs of incubation in the clotting times. Taken together these results indicated that the LPS system was efficient until 6hrs and could prolong milk shelf life and prevent milk clotting.

Identification and Characterization of Menadione and Benzethonium Chloride as Potential Treatments of Pierce's Disease of Grapevines.

Xylella fastidiosa infects a wide range of plant hosts and causes Pierce's disease (PD) of grapevines. The type 1 multidrug resistance (MDR) efflux system is essential for pathogenicity and survival of bacterial pathogens in planta. X. fastidiosa, with a single MDR system, is significantly more vulnerable to inhibition by small-molecule treatments than most bacterial pathogens that typically carry redundant MDR systems. A high-throughput cell viability assay using a green fluorescent protein-marked strain of X. fastidiosa Temecula 1 was developed to screen two Prestwick combinatorial small-molecule libraries of drugs and phytochemicals (1,600 chemicals in total) approved by the Food and Drug Administration and European Medicines Agency for cell growth inhibition. The screens revealed 215 chemicals that inhibited bacterial growth by >50% at 50 µM concentrations. Seven chemicals proved to lyse X. fastidiosa cells at 25 µM, including four phytochemicals. Menadione (2-methyl-1,4-naphthoquinone, vitamin K) from the phytochemical library and benzethonium chloride (a topical disinfectant) from the chemical library both showed significant bactericidal activity against X. fastidiosa. Both menadione and benzethonium chloride foliar spray (15 and 5 mM, respectively) and soil drench (5 and 25 mM, respectively) treatments were equally effective in reducing PD symptoms by 54 to 59% and revealed that the effects of both chemical treatments became systemic. However, menadione was phytotoxic when applied as a foliar spray at effective concentrations, causing significant loss of photosynthetic capacity.

Characterization of biofilm formation by Salmonella enterica at the air-liquid interface in aquatic environments.

Survival of bacterial pathogens in different environments is due, in part, to their ability to form biofilms. Four wild-type Salmonella enterica strains, two Oranienburg and two Saintpaul isolated from river water and animal feces, were tested for biofilm formation at the air-liquid interface under stressful conditions (pH and salinity treatments such as pH3, NaCl 4.5 w/v; pH7, NaCl 4.5 w/v; pH10, NaCl 4.5 w/v; pH3, Nacl 0.5 w/v; pH7, NaCl 0.5 w/v; and pH10, NaCl 0.5 w/v); Salmonella Typhimurium DT104 was used as a control strain. Salmonella Oranienburg and Saintpaul from feces were moderately hydrophobic and motile, while S. Saintpaul from water and the control strain S. Typhimurium showed high hydrophobicity, which helped them form more resistant biofilms than S. Oranienburg. Under stressful conditions, all strains experienced difficulties in forming biofilms. Salmonella Saintpaul and Typhimurium expressed the red dry and rough (RDAR) morphotype and were able to form biofilm at air-liquid interface, contrarily to Oranienburg that showed incomplete rough morphology. This study contributes to the knowledge of biofilm formation as a survival strategy for Salmonella in aquatic environments.

Antibacterial, antioxidant and Immuno-modulatory properties in extracts of Barleria lupulina Lindl.

BackgroundAntibacterial, immunomodulatory and antioxidant properties of aerial parts of Barleria lupulina Lindl were investigated in the present communication.MethodsThe antibacterial, antioxidant and immunomodulatory properties of B. lupulina (methanol soluble leaf and stem extracts) was analyzed by minimum inhibitory concentration, total phenolic contents, DPPH radical scavenging activity, determination of toxicity, hemagglutination antibody titre, delayed type hypersensitivity and neutrophil adhesion test, respectively.ResultsMethanol soluble leaf extract (MLE) contains more soluble bioactive compounds inhibiting the growth of five bacterial pathogens viz., Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Salmonella typhi even at MICs of 1.25 and 2.5 mg/mL. Aqueous stem extract (ASE) was least effective while MLE was highly effective in inhibiting the growth and survival of bacterial pathogens. While testing the effect of these extracts in animal model, no mortality of albino rats was recorded by using MLE and MSE at the concentrations from 200 to 600 mg/kg of their body weight. The MLE showed significant result in agglutination reaction and induced paw edema volumes when compared with untreated group (control). Both MLE and MSE extracts significantly increased neutrophil adhesion with increase in doses of extracts. MLE was found to have more potent immune-stimulant properties than the MSE. High phenolic contents were found in MSE while lowest IC50 values were found in MLE in term of DPPH radical scavenging activity.ConclusionsMethanol soluble leaf and stem extract of Barleria lupulina contains antibacterial, antioxidants and immunomodulating phytochemical compounds that was effective for antibacterial, antioxidant and immunomodulatory properties. These may be used as synthetic drug.

Importance of Soil Amendments: Survival of Bacterial Pathogens in Manure and Compost Used as Organic Fertilizers

Biological soil amendments (BSAs) such as manure and compost are frequently used as organic fertilizers to improve the physical and chemical properties of soils. However, BSAs have been known to be a reservoir for enteric bacterial pathogens such as enterohemorrhagic Escherichia coli (EHEC), Salmonella spp., and Listeria spp. There are numerous mechanisms by which manure may transfer pathogens to growing fruits and vegetables, and several outbreaks of infections have been linked to manure-related contamination of leafy greens. In the United States several commodity-specific guidelines and current and proposed federal rules exist to provide guidance on the application of BSAs as fertilizers to soils, some of which require an interval between the application of manure to soils and the harvest of fruits and vegetables. This review examines the survival, persistence, and regrowth/resuscitation of bacterial pathogens in manure, biosolids, and composts. Moisture, along with climate and the physicochemical properties of soil, manure, or compost, plays a significant role in the ability of pathogens to persist and resuscitate in amended soils. Adaptation of enteric bacterial pathogens to the nonhost environment of soils may also extend their persistence in manure- or compost-amended soils. The presence of antibiotic-resistance genes in soils may also be increased by manure application. Overall, BSAs applied as fertilizers to soils can support the survival and regrowth of pathogens. BSAs should be handled and applied in a manner that reduces the prevalence of pathogens in soils and the likelihood of transfer of food-borne pathogens to fruits and vegetables. This review will focus on two BSAs-raw manure and composted manure (and other feedstocks)-and predominantly on the survival of enteric bacterial pathogens in BSAs as applied to soils as organic fertilizers.

CRISPR/Cas システム： 微生物における新規機能とゲノム編集適用例

CRISPR/Cas システムは真正細菌および古細菌に広く保存され、外来性遺伝子の一部を自身の染色体に取り込み記憶することで、同一の外来性遺伝子が再度侵入した場合には、これらを分解・排除する獲得免疫機構として機能する。最近では、獲得免疫機構としてだけでなく、細菌の毒性や病原性に関与していること、様々な環境下での細菌の生存や進化においても重要な役割を担っていることが明らかになりつつある。本総説においては近年の我々の研究成果を交え、最新の研究トピック、特に細菌の生存戦略におけるCRISPR/Cas システムの役割を概説する。また、優れたゲノム編集技術としてのCRISPR/Cas システムの適用例を簡単ではあるが紹介したい。

RA PD-ANALYS IS OF PSEUDOMONAS SYRINGAE, ISOLATED FROM WEEDS IN AGRO PHYTO CENOS IS OF WHEAT

Aim. Investigation of the genetic diversity of Pseudomonas syringae strains, isolated from various weeds: horsetail, field bindweed, barnyard grass, sow-thistle, bedstraw, wild radish, orache white whith had the signs of bacterial affection. Methods. RAPD-PGR analysis. Results. Pseudomonas syringae strains, isolated from various species of weeds in wheat agrophytocenosis, were analyzed. We have established the relationship of studied strains with neopatotype strain Pseudomonas syringae pv. atrofaciens PDDCC 4394, and the type strains of Pseudomonas syringae pv. syringae NCPPB 281. Most isolated strains had a high level of affinity with basal bacteriosis pathogen of wheat Pseudomonas syringae pv. atrofaciens which is the most common among the crops. Bacterial blight pathogen Pseudomonas syringae pv. syringae is less widespread and only three bacteria stains isolated from weeds had common reaction. Conclusion. P. syringae strains isolated from different types of weeds and Pseudomonas syringae pv. syringae NCPPB and Pseudomonas syringae pv. atrofaciens PDDCC4394 strains, pathogens of bacterial diseases of wheat are genetically homogeneous group. Our data support the hypothesis that weeds are one of the ecological niches of conservation and survival of bacterial pathogens and under favorable conditions can be a source of infection.

CRISPR-Cas immunity against phages: its effects on the evolution and survival of bacterial pathogens.

Clustered regularly interspaced short palindromic repeats (CRISPR) loci are arrays of short repeats separated by equally short “spacer” sequences [1]–[3]. Along with the CRISPR-associated (cas) genes, they encode an adaptive immune system of archaea and bacteria that protects the cell against viral infection [4]. Remarkably, this system is capable of inserting a short piece of an infecting viral genome as a spacer in the CRISPR array [4], [5] (Figure 1A). The spacer sequence is transcribed and processed to generate a small antisense RNA (the CRISPR RNA or crRNA) (Figure 1B) [6] that is used as a guide for the recognition and destruction of the invader in subsequent infections (Figure 1C) [7]. Thus, spacer acquisition immunizes the bacterium and its progeny against the virus from which it was taken. Because spacers are incorporated in sequential order, CRISPR loci reflect the history of viral infection of the host. Cas proteins participate in all the different steps of this pathway, namely the insertion of spacer sequences into the CRISPR array [8], [9], the biogenesis of crRNAs [10], [11], and the destruction of the infecting viral genome [12], [13]. Figure 1 The CRISPR immunity pathway. Distribution of CRISPR-Cas Loci among Bacterial Pathogens In spite of the unique role that CRISPR-Cas loci play in antiviral defense, they are not universal. To date, the CRISPR database [14], a webtool that determines the presence of CRISPR arrays in completed genomes, indicates that 119/141 archaeal (84%) and 1012/2113 bacterial (48%) genomes contain CRISPR loci. In bacteria, there are species in which all strains have CRISPR loci, some in which only some strains have these loci, and species without strains having CRISPR loci. Therefore it is not possible to determine unequivocally that lack of CRISPR in certain strains or species is due to loss of these loci. However, because CRISPR sequences are spread thorough horizontal gene transfer [15], [16] and can be easily lost [17]–[20], it has been hypothesized recently that CRISPR are in a constant state of flux and can appear and disappear depending on the selective forces of the environment [20]. The same type of uneven distribution is found when we look at the presence of CRISPR loci in bacterial pathogens in the CRISPR database (http://crispr.u-psud.fr/crispr/).

Original Research: Survival of Bacterial Pathogens on Paper and Bacterial Retrieval from Paper to Hands: Preliminary Results

Paper is omnipresent on hospital units, but few studies have examined the possible role of paper in the spread of nosocomial pathogens. To determine by laboratory investigation how long bacterial pathogens can survive on office paper and whether bacteria can be transferred from hands to paper and back to hands in a "worst-case scenario." Samples of four bacterial pathogens (Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Enterococcus hirae) were prepared according to standard laboratory procedures. Sterile swatches of office paper were inoculated with the pathogens and bacterial survival was tested over seven days. To test the transmission of bacteria from one person's hands to paper and back to another person's hands, the fingertips of volunteers were inoculated with a nonpathogenic strain of E. coli; these volunteers then pressed the inoculum onto sterile paper swatches. Another group of volunteers whose hands had been moistened pressed their fingertips onto the contaminated paper swatches. Bacteria transferred to the moistened fingertips were cultivated according to standard laboratory procedures. The four tested organisms showed differences in length of survival depending on environmental room conditions, but were stable on paper for up to 72 hours and still cultivable after seven days. Test organisms were transferred to paper, survived on it, and were retransferred back to hands. Paper can serve as a vehicle for cross-contamination of bacterial pathogens in medical settings if current recommendations on hand hygiene aren't meticulously followed.

CE Test 2.1 Hours: Survival of Bacterial Pathogens on Paper and Bacterial Retrieval from Paper to Hands: Preliminary Results

CE Test 2.1 Hours: Survival of Bacterial Pathogens on Paper and Bacterial Retrieval from Paper to Hands: Preliminary Results

Mobility and survival of Salmonella Typhimurium and human adenovirus from spiked sewage sludge applied to soil columns

This study investigated the survival and transport of sewage sludge-borne pathogenic organisms in soils. Undisturbed soil cores were treated with Salmonella enterica ssp. enterica serovar Typhimurium-lux (STM-lux) and human adenovirus (HAdV)-spiked sewage sludge. Following an artificial rainfall event, these pathogens were analysed in the leachate and soil sampled from different depths (0-5 cm, 5-10 cm and 10-20 cm) after 24 h, 1 and 2 months. Significantly more STM-lux and HAdV leached through the soil cores when sewage sludge was present. Significantly more STM-lux were found at all soil depths, at all time periods in the sewage sludge treatments, compared to the controls. The rate of decline of STM-lux in the controls was more rapid than in the sewage sludge treatments. Survival and transport of HAdV were minimal. The presence of sewage sludge can significantly influence the transport and survival of bacterial pathogens in soils, probably because of the presence of organic matter. Environmental contamination by virus is unlikely because of strong soil adsorption. This study suggests that groundwater contamination from vertical movement of pathogens is a potential risk and that it highlights the importance of the treatment requirements for biosolids prior to their application to land.

Survival of bacterial pathogens during the thermophilic anaerobic digestion of biowaste: Laboratory experiments and in situ validation

Anaerobic digestion is continually gaining importance for the processing of the organic fraction of municipal solid wastes. Although methods for studying the survival of pathogen exist, these methods often need adaptations, are expensive, time consuming or generally not well suited for the harsh conditions within an anaerobic digestion system. In the present study we investigated the applicability of commercially available, mechanically stable and inexpensive pathogen carriers to validate in situ pathogen inhibition within a 750,000 l thermophilic, bio-waste treating anaerobic digester. None of the pathogens investigated ( Listeria monocytogenes, Salmonella enterica, Escherichia coli, and Campylobacter jejuni) was capable of survival under the conditions of the biogas reactor for more than 24 h indicating that the temperature and physico-chemical properties of the sludge of the fermenter were effective in inhibiting the survival of these microorganisms.

Unique Features of the sodC-encoded Superoxide Dismutase from Mycobacterium tuberculosis, a Fully Functional Copper-containing Enzyme Lacking Zinc in the Active Site

The sodC-encoded Mycobacterium tuberculosis superoxide dismutase (SOD) shows high sequence homology to other members of the copper/zinc-containing SOD family. Its three-dimensional structure is reported here, solved by x-ray crystallography at 1.63-A resolution. Metal analyses of the recombinant protein indicate that the native form of the enzyme lacks the zinc ion, which has a very important structural and functional role in all other known enzymes of this class. The absence of zinc within the active site is due to significant rearrangements in the zinc subloop, including deletion or mutation of the metal ligands His115 and His123. Nonetheless, the enzyme has a catalytic rate close to the diffusion limit; and unlike all other copper/zinc-containing SODs devoid of zinc, the geometry of the copper site is pH-independent. The protein shows a novel dimer interface characterized by a long and rigid loop, which confers structural stability to the enzyme. As the survival of bacterial pathogens within their host critically depends on their ability to recruit zinc in highly competitive environments, we propose that the observed structural rearrangements are required to build up a zinc-independent but fully active and stable copper-containing SOD.

Effect of Organic Acids and Temperature on Survival of Shigella flexneri in Broth at pH 4

The survival of bacterial pathogens in acidified foods depends not only on the hydrogen ion concentration, but also on the type of acid and the storage temperature. Shigella flexneri is a foodborne pathogen that is acid tolerant. The survival of S. flexneri 5348 in brain heart infusion broth supplemented with 0.04M acetic, citric, lactic, malic, or tartaric acid and adjusted to pH 4 with HCl or NaOH was studied. The control medium was brain heart infusion broth adjusted to pH 4 with HCl. Stationary-phase cells were inoculated into media at initial populations of 6 to 7 log10 CFU/ml and incubated at 4, 19, 28, and 37°C. A two-phase linear inactivation model was applied to plate count data to derive lag times (tL) and slopes of the curves, from which D-values and time required for a 4-log10 decrease in population (T4D) were calculated. In all cases, survival increased with decreasing temperature. For each acid, tL, the D-value, and T4D increased with decreasing temperature. All acids inhibited S. flexneri to some extent but to differing degrees as follows: lactic acid, acetic acid > citric acid, malic acid, tartaric acid > HCl. The T4D values for the control medium and for media containing acetic, citric, lactic, malic, and tartaric acids were 64, 47, 50, 34, 58, and 52 h, respectively, at 37°C and 2,607, 1,498, 1,905, 1,346, 1,726, and 2,134 h, respectively, at 4°C. The results of this study indicate that organic acids may aid in the inactivation of Shigella. However, these data also suggest that foods stored at or below room temperature containing low levels (<1%) of acids could cause illness if contaminated with Shigella.

Survival of Bacterial Pathogens in Pasteurized Process Cheese Slices Stored at 30°C

Six lots of commercial pasteurized process cheese slices were evaluated for the ability to support the growth of four foodborne pathogens, Listeria monocytogenes, Staphylococcus aureus, Salmonella serotypes, and Escherichia coli O157:H7, during 4 days of storage at 30°C. Individual cheese slices were inoculated separately with each pathogen to yield ca. 103 CFU/g. Slices were packaged in sterile plastic sample bags and stored at 30°C for up to 96 h. Populations of Salmonella serotypes and Escherichia coli O157:H7 decreased an average of 1.3 and 2.1 log10 CFU/g, respectively, by 36 h and Salmonella serotypes decreased an additional 0.6 logi0 CFU/g during the remaining 60 h. Populations of Listeria monocytogenes also decreased, although to a lesser extent, exhibiting approximately a 0.6-log10 CFU/g reduction in 96 h. Staphylococcus aureus levels remained relatively constant during the testing period, and were below levels that support detectable enterotoxin production. The process cheese slices tested allowed survival but did not support rapid growth of S. aureus, whereas populations of L. monocytogenes, E. coli O157:H7, and Salmonella serotypes decreased during the 96-h storage at 30°C.

Trojan horses of the microbial world: protozoa and the survival of bacterial pathogens in the environment.

Trojan horses of the microbial world: protozoa and the survival of bacterial pathogens in the environment.