An alternative infrared spectroscopy assay for the quantification of polysaccharides in bacterial samples

Pathogenic bacteria are generally studied as a single strain under ideal growing conditions, although these conditions are not the norm in the environments in which pathogens typically proliferate. In this investigation, a representative microbial community along with Escherichia coli O157:H7, a model pathogen, was studied in three environments in which such a pathogen could be found: a human colon, a septic tank, and groundwater. Each of these systems was built in the lab in order to retain the physical/ chemical and microbial complexity of the environments while maintaining control of the feed into the models. The microbial community in the colon was found to have a high percentage of bacteriodetes and firmicutes, while the septic tank and groundwater systems were composed mostly of proteobacteria. The introduction of E. coli O157:H7 into the simulated systems elicited a shift in the structures and phenotypic cell characteristics of the microbial communities. The fate and transport of the microbial community with E. coli O157:H7 were found to be significantly different from those of E. coli O157:H7 studied as a single isolate, suggesting that the behavior of the organism in the environment was different from that previously conceived. The findings in this study clearly suggest that to gain insight into the fate of pathogens, cells should be grown and analyzed under conditions simulating those of the environment in which the pathogens are present.

Section: Discussionmentioning

confidence: 86%

Linking Microbial Community Structure to Function in Representative Simulated Systems

Marcus

Wilder

Quazi

et al. 2013

“…Amide II bands represent 60% N-H bending and 40% C-N stretching (51). Any changes in amide II bands represent changes in secondary proteins, as reported by Carpenter and Crowe (6), Leslie and others (33), and Marcotte and others (35). The amide II band alteration indicated a change in secondary protein structures, such as a decrease in the number of native ␣-helices and an increase in the number of ␤-sheets (50).…”

Section: Discussionmentioning

confidence: 98%

“…The use of amide I is unreliable compared to amide II, as the CAO stretching vibration of alginate interferes with amide I bands (35). Amide II bands represent 60% N-H bending and 40% C-N stretching (51).…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Role of Calcium Alginate and Mannitol in Protecting Bifidobacterium

Dianawati

Mishra

Shah

2012

ABSTRACTFourier transform infrared (FTIR) spectroscopy was carried out to ascertain the mechanism of Ca-alginate and mannitol protection of cell envelope components and secondary proteins ofBifidobacterium animalissubsp.lactisBb12 after freeze-drying and after 10 weeks of storage at room temperature (25°C) at low water activities (aw) of 0.07, 0.1, and 0.2. Preparation of Ca-alginate and Ca-alginate-mannitol as microencapsulants was carried out by dropping an alginate or alginate-mannitol emulsion containing bacteria using a burette into CaCl2solution to obtain Ca-alginate beads and Ca-alginate-mannitol beads, respectively. The wet beads were then freeze-dried. The awof freeze-dried beads was then adjusted to 0.07, 0.1, and 0.2 using saturated salt solutions; controls were prepared by keeping Ca-alginate and Ca-alginate-mannitol in aluminum foil without awadjustment. Mannitol in the Ca-alginate system interacted with cell envelopes during freeze-drying and during storage at low aws. In contrast, Ca-alginate protected cell envelopes after freeze-drying but not during 10-week storage. Unlike Ca-alginate, Ca-alginate-mannitol was effective in retarding the changes in secondary proteins during freeze-drying and during 10 weeks of storage at low aws. It appears that Ca-alginate-mannitol is more effective than Ca-alginate in preserving cell envelopes and proteins after freeze-drying and after 10 weeks of storage at room temperature (25°C).

“…4a for the amide II band. This increase reflected biofilm development and bacterial cells dividing on and colonizing the IRE surface (11) and producing extracellular polymeric substances (EPS) (16,29). The overproduction of EPS by bacterial cells during attachment to an inert substratum is well documented (3,12,13,41,51).…”

Section: Nascent Biofilm Development Under Lb Medium Flow Conditionsmentioning

confidence: 99%

In Situ Monitoring of the Nascent Pseudomonas fluorescens Biofilm Response to Variations in the Dissolved Organic Carbon Level in Low-Nutrient Water by Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy

Delille

Quilès

Humbert

2007

Drinking water quality management requires early warning tools which enable water supply companies to detect quickly and to forecast degradation of the microbial quality of drinking water during its transport throughout distribution systems. This study evaluated the feasibility of assessing, in real time, drinking water biostability by monitoring in situ the evolution of the attenuated total reflectance-Fourier transform infrared (ATR-FTIR) fingerprint of a nascent reference biofilm exposed to water being tested. For this purpose, the responses of nascent Pseudomonas fluorescens biofilms to variations in the dissolved organic carbon (DOC) level in tap water were monitored in situ and in real time by ATR-FTIR spectroscopy. Nascent P. fluorescens biofilms consisting of a monolayer of bacteria were formed on the germanium crystal of an ATR flowthrough cell by pumping bacterial suspensions in Luria-Bertani (LB) medium through the cell. Then they were exposed to a continuous flow of dechlorinated sterile tap water supplemented with appropriate amounts of sterile LB medium to obtain DOC concentrations ranging from 1.5 to 11.8 mg/liter. The time evolution of infrared bands related to proteins, polysaccharides, and nucleic acids clearly showed that changes in the DOC concentration resulted in changes in the nascent biofilm ATR-FTIR fingerprint within 2 h after exposure of the biofilm to the water being tested. The initial bacterial attachment, biofilm detachment, and regrowth kinetics determined from changes in the areas of bands associated with proteins and polysaccharides were directly dependent on the DOC level. Furthermore, they were consistent with bacterial adhesion or growth kinetic models and extracellular polymeric substance overproduction or starvation-dependent detachment mechanisms.The biological stability of drinking water in distribution systems is a major concern of water supply companies (14), consumers, regulators, and public health authorities alike (1, 7). Bacterial regrowth within distribution systems is dependent upon a complex interaction of chemical, physical, operational, and engineering parameters (52). In particular, temperature, pH, disinfectant residual, hydrodynamic conditions, residence time, pipe materials, and above all the availability and composition of biodegradable organic matter are key factors in microorganism regrowth processes (37). Drinking water biostability is commonly assessed by biomass-based or biodegradability methods (37,45,47). Unfortunately, because of a slow response (usually more than 24 h) and/or batch processing these methods do not enable in situ real-time monitoring of microbiological quality. Moreover, culture-based methods do not reflect the actual dynamics of the attached bacterial films on pipe surfaces, which play a major role in postdisinfection biological regrowth (27,33). Consequently, in addition to these methods, managing finished water quality requires early warning devices which enable workers to detect quickly, or even to forecast, degradation of drink...