Beata Cwalina

Raman spectroscopic study of glutaraldehyde-stabilized collagen and pericardium tissue

For the first time, Raman spectroscopy has been employed to investigate formation of cross-links in collagen and porcine pericardium tissue upon glutaraldehyde (GA) treatment. GA treatment causes a very high fluorescence background, which overlaps Raman bands. It has been found that short fixation time, i.e. 2 h, reduces background radiation significantly, providing new possibilities for studying changes in molecular structure of collagen upon GA modification. The observed changes in position and intensity of Raman bands allowed us to recognize different types of GA–collagen interactions. Strong spectral evidence has been found for the peptide contribution to the formation of the GA–collagen cross-links and for the formation of secondary amines via Schiff base intermediates, and pyridinium-type cross-links. The results also revealed that different hydration levels and a more complex structure of intact tissue in comparison to collagen preparation strongly influence the formation of a GA cross-linking network, e.g. ether-type bond is preferred to form in a less hydrated collagen preparation. Our results have shown that GA treatment causes an increase in water content of pericardium tissue and collagen.

Dependence of effectiveness of leaching of metallic sulphides on enzymes involved in inorganic sulphur metabolism in Thiobacillus ferrooxidans

SummaryThe leaching activity of five batches of Thiobacillus ferrooxidans, strain F26-77, cultivated under various conditions, towards elemental sulphur, ferrous ions, pyrite, covellite, chalcopyrite and sphalerite was studied. The activities of sulphite oxidase, thiosulphate oxidase and rhodanese were determined in crude, cell-free bacterial extracts. The effectiveness of leaching was directly correlated with the enzymic activity of the cultures. The results suggest that the activities of the enzymes metabolizing sulphur and its inorganic compounds in Thiobacillus ferrooxidans, or bacterial leaching activity on sulphur and sulphides, rather than the rate of oxidation of ferrous ions, should be taken as the criterion of usefulness for the leaching of sulphide minerals.

Biofilm Formation on NiTi Surface by Different Strains of Sulphate Reducing Bacteria (Desulfovibrio desulfuricans)

Bacteria of Desulfovibrio genus belong to group of widespread sulphate-reducing bacteria (SRB). D. desulfuricans is considered one among many bacterial species involved in microbiologically influenced corrosion (MIC) of metals, mainly of stainless steels and other alloys. SRB can produce gaseous hydrogen sulphide. This gas is released into the environment leading to formation of metal sulphides that significantly influence electrochemical processes and ultimately enhance the corrosion of materials. Biofilms formed by these bacteria are especially harmful for highly alloyed steels and many alloys. The aim of this work was to compare the character of growth and biofilm formation by three strains of D. desulfuricans (standard soil strain DSM and two wild intestinal strains: DV/A and DV/B) on the surface of NiTi alloy.

Activity of sulphite oxidase, thiosulphate oxidase and rhodanese in Thiobacillus ferrooxidans during covellite and chalcopyrite leaching

SummaryThe activities of enzymes involved in inorganic sulphur metabolism in crude, cell-free extracts of Thiobacillus ferrooxidans, strain F26-77 were determined during bacterial leaching of covellite and chalcopyrite. Increase in the specific activity of sulphide oxidase, thiosulphate oxidase and rhodanese during the leaching of both minerals was demonstrated. Simultaneously a decrease in the extraction rate of copper from the leached materials was observed.

Effect of Artificial and Inflammatory Saliva on Desulfovibrio desulfuricans Growth and Biofilm Formation on NiTi Alloy

NiTi alloys are used for both medical and veterinary purposes, and also for production of surgical instruments. Sulphate-reducing bacteria (SRB) colonize various anaerobic environments, including human oral cavity. Desulfovibrio desulfuricans is the SRB species responsible for corrosion of many metals including highly alloyed steels as well as titanium and its alloys. The aim of this work was to compare growth of D. desulfuricans biofilms on NiTi alloy submerged in artificial saliva or in inflammatory saliva. The results of investigations showed differences between D. desulfuricans biofilms formed on NiTi alloy in the presence of artificial saliva and inflammatory saliva. The growth medium influenced biofilm structure; inflammatory saliva promotes its formation. The biofilms grown on samples immersed in inflammatory saliva were much thicker as compared with samples emerged in artificial saliva. After 28 days of incubation in inflammatory saliva, plentiful mature biofilm was present on alloy surface.

Initial stage of the biofilm formation on the NiTi and Ti6Al4V surface by the sulphur-oxidizing bacteria and sulphate-reducing bacteria

The susceptibility to the fouling of the NiTi and Ti6Al4V alloys due to the adhesion of microorganisms and the biofilm formation is very significant, especially in the context of an inflammatory state induced by implants contaminated by bacteria, and the implants corrosion stimulated by bacteria. The aim of this work was to examine the differences between the sulphur-oxidizing bacteria (SOB) and sulphate-reducing bacteria (SRB) strains in their affinity for NiTi and Ti6Al4V alloys. The biofilms formed on alloy surfaces by the cells of five bacterial strains (aerobic SOB Acidithiobacillus thiooxidans and Acidithiobacillus ferrooxidans, and anaerobic SRB Desulfovibrio desulfuricans—3 strains) were studied using scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). The protein concentrations in liquid media have also been analyzed. The results indicate that both alloys tested may be colonized by SOB and SRB strains. In the initial stage of the biofilm formation, the higher affinity of SRB to both the alloys has been documented. However, the SOB strains have indicated the higher (although differentiated) adaptability to changing environment as compared with SRB. Stimulation of the SRB growth on the alloys surface was observed during incubation in the liquid culture media supplemented with artificial saliva, especially of lower pH (imitated conditions under the inflammatory state, for example in the periodontitis course). The results point to the possible threat to the human health resulting from the contamination of the titanium implant alloys surface by the SOB (A. thiooxidans and A. ferrooxidans) and SRB (D. desulfuricans).Graphical abstract

Differences between A. thiooxidans and A. ferrooxidans Biofilms Formed on Concrete and Stoneware

Sulfur-oxidizing bacteria (SOB) of Acidithiobacillus genus, especially of A. thiooxidans and A.ferrooxidans species are considered as very aggressive biological factors that influences deterioration of many materials, including mineral building materials like concrete and stoneware. Biofilms formed by these bacteria play a significant role in microbiologically influenced corrosion (MIC) of various materials in conditions that ensure sufficient moisture. The aim of this work was to assess differences between A. thiooxidans and A. ferrooxidans biofilms formed on concrete and stoneware. Both strains were prone to form biofilms on concrete and stoneware. However, the type of mineral materials strongly influenced metabolic activities of the tested strains, thus providing to formation of biofilms displaying different features. The higher activities of cells were observed in biofilms of A.ferrooxidans bacteria. The higher total biomass attached to the material surface as well as concentration of proteins in liquid culture medium were observed in biofilms grown on concrete samples. The optimal time of biofilm growth on tested materials was 48 hours on concrete, and 72 hours on stoneware. Amongst materials tested, concrete samples were more susceptible to corrosion in the presence of A. thiooxidans and A. ferrooxidans bacteria.

Diffuse Reflectance Infrared Fourier Transform Spectra of Biofilm-Containing Sediments: Influence of Sample Lyophilization and Drying Temperature

Monitoring of biofilms in sediments formed inside drinking water distribution systems is important due to their destructive activity and their degradation of water quality. The goal of this study was to examine the influence of drying mode and temperature upon sediments containing biofilms using diffuse reflectance infrared Fourier transform spectroscopy. Sediments were collected from sections of potable water pipes and dried at 22, 40, 105 degrees Celsius, or lyophilized. The presence of biofilm residues was demonstrated. Lyophilization of biofilms and drying at temperatures higher than 22 degrees Celsius affected the infrared spectra. The least invasive method involved air-drying of the biofilms at 22 degrees Celsius.