Formation of antibodies against bacterial polysaccharides by peripheral leucocytes

Summary We studied the dynamics of antibody-producing cells in peripheral blood after immunization withSalmonella paratyphi B. We found that antibody formation started on the second day, reached maximum values by the fourth day and fell by the 9th–12th day. PFC are probably released by the spleen into the peripheral blood, where they form maximally 10% of PFC values in the spleen. Fractionation of the sera and study of the effect of gamma globulin antiserum showed that anti-bodies formed in response to bacterial polysaccharide are mainly of the macroglobulin type.     

Conformational studies of bacterial polysaccharides. II. Optical activity of some bacterial capsular polysaccharides

The optical activity of the Klebsiella capsular polysaccharides of serotypes K1, K5, K6, K8, K11, K56, and K57 has been studied in aqueous solution. Measurements of ORD in the range 185–450 nm reveal anomalous ORD with Cotton effects near λ₀ = 195nm. The results are evaluated quantitatively according to hte Moffitt-Yang and the Drude equations. Straight lines are obtained in the Moffitt-Yang plots, while the corresponding Drude plots yield bent curves. The b₀ values, calculated from the slope of the stright lines in the Moffitt-Yang plot, range from 90 to 270 and suggest a helical superstructure for the capsular polysaccyharides. Positive b₀ values have been found for K1, K5, and K6 and negative b₀ values for K8, k11, K56, ad K57. Circular dichrosim has been mesured, but the CD curves are found to be truncated at the lower-wavelength end due to the 185-nm limit of the spectrometer used. Measurements of the temperature dependence of the specific optical rotation [α] reveal in all cases cooperative order–disorder transitions at temperatures, T_m, fro m298 to 323°K. The van′t Hoff enthalpies derived from the width of the transition curves are found to be similar in value to those of polypeptieds in aqueous solution. The K8 polysaccharide shows a two-step transition. The results are discussed in relation to the known primary structure and x-ray data from oriented and partially crystalline films. A model is suggested for the two-step transition in the K8 polysaccharide.     

Uptake of bacterial DNA by Chlamydomonas reinhardi

Escherichia coli [³H]DNA supplied to vegetative cultures of wild-type (mt+) and CW15 (mt+; mutant lacking the cell wall) Chlamydomonas reinhardi could bind to the cell wall of the wild-type and to the cell membrane of CW15 mutant cells. The extent of this binding decreased with time and was to a large degree (over 90%) DNA-ase-sensitive. Nevertheless, about 0.01% of the bacterial DNA remained irreversibly associated with the cells when they reached stationary phase. The irreversible binding of the donor bacterial DNA to Chlamydomonas cells could be increased by treatment of the cultures with polycations such as DEAE-dextran, poly-L-lysine and poly-L-ornithine. Although the CW15 cells rapidly degraded bacterial DNA in the culture medium wild-type cells showed only a small effect on the molecular weight of the donor DNA.The acid-insoluble radioactivity irreversibly bound to WT (+) cells consisted mainly of oligonucleotides with a small proportion present as less depolymerized donor DNA. No radioactivity, however, was found to be associated with the recipient high molecular weight Chlamydomonas DNA.No labeled donor DNA could be recognized in the cells given bacterial [³H]DNA in early stationary phase. Instead, radioactivity found in Chlamydomonas DNA corresponded to reutilization of [³H]thymine derivatives released as a result of [³H] DNA degradation. No evidence for the integration of detectable amounts of donor DNA sequences into the host cell DNA was obtained.     

The use of bacterial polysaccharides in bioprinting

Additive manufacturing or 3D printing has spearheaded a revolution in the biomedical sector allowing the rapid prototyping of medical devices. The recent advancements in bioprinting technology are enabling the development of potential new therapeutic options with respect to tissue engineering and regenerative medicines. Bacterial polysaccharides have been shown to be a central component of the inks used in a variety of bioprinting processes influencing their key features such as the mechanical and thermal properties, printability, biocompatibility, and biodegradability. However, the implantation of any foreign structure in the body comes with an increased risk of bacterial infection and immunogenicity. In recent years, this risk is being potentiated by the rise in nosocomial multidrug-resistant bacterial infections. Inks used in bioprinting are being augmented with antimicrobials to mitigate this risk. The applications of bacterial polysaccharide-based bioinks have the potential to act as a key battlefront in the war against antibiotic resistance. This paper reviews the range of bacterial polysaccharides used in bioprinting and discusses the potential of various bioactive polysaccharides to be integrated into these inks.     

Uptake and retention of metals by cell walls of Bacillus subtilis.

Isolated walls of Bacillus subtilis Marburg, prepared in a manner which avoided metal contamination other than by the growth medium, were incubated in dilute metal solutions, separated by membrane filtration (0.22 mum), and monitored by atomic absorption to give uptake data for 18 metals. Substantial amounts of Mg2+, Fe3+, Cu2+, Na+, and K+ (amounts which were often visible as Au3+, and Ni2+ (the higher atomic-numbered elements also visible as electron scattering), and small amounts of Hg2+, Sr2+, Pb2+, and Ag+ were taken into the wall. Some (Li+, Ba2+, Co2+, and Al3+) were not absorbed. Most metals which had atomic numbers greater than 11 and which could be detected by electron microscopy appeared to diffusely stain thin sections of the wall. Magnesium, on the other hand, partitioned into the central region, and these sections of walls resisted ruthenium red staining, which was not true for the other metals. Areas of the walls also acted as nucleation sites for the growth of microscopic elemental gold crystals when incubated in solutions of auric chloride. Retention or displacement of the metals was estimated by a "chromatographic" method using the walls cross-linked by the carbodiimide reaction to adipic hydrazide agarose beads (which did not take up metal but reduced the metal binding capacity of the walls by ca. 1%) packed in a column. When a series of 12 metal solutions was passed through the column, it became evident that Mg2+, Ca2+, Fe3+, and Ni2+ were strongly bound to the walls and could be detected by both atomic absorption and by their electron-scattering power in thin sections, qhereas the other metals were fisplaced or replaced. Partial lysozyme digestion of the walls (causing a 28% loss of a [3H]diaminopimelic acid label) greatly diminished the Mg2+ retention but not that of Ca2+, Fe3+, or Ni2+, indicating that there are select sites for various cations.     

Uptake of trace metals by sediments and suspended particulates: a review

This review addresses three of the possible mechanisms by which trace metals can be concentrated by sediments and suspended particulate matter. These are physico-chemical adsorption from the water column, biological uptake particularly by bacteria and algae, and the sedimentation and physical entrapment of enriched particulate matter. The relative importance of these three mechanisms will be different, depending upon the aqueous system, but there have been insufficient studies to allow the establishment of even rule-of-thumb guidelines, as yet, about their quantitative importance under different conditions.The importance of natural organic matter in the cycling of trace metals in aquatic systems has been stressed. This organic matter may complex with the trace metals and keep them in solution, or it may enhance the association of the trace metals with particulate matter by becoming adsorbed to the particulate surface and then complexing with the trace metals in the solution phase. Enhanced metal-particulate associations may also arise if the metal-organic complexes are able to adsorb to the surface.The behaviour of natural organic matter may be the single most important influence on trace metal cycling in aquatic systems and should receive considerably more attention in the future.     

Recognition of bacterial capsular polysaccharides and lipopolysaccharides by the macrophage mannose receptor

The in vitro binding of the macrophage mannose receptor to a range of different bacterial polysaccharides was investigated. The receptor was shown to bind to purified capsular polysaccharides from Streptococcus pneumoniae and to the lipopolysaccharides, but not capsular polysaccharides, from Klebsiella pneumoniae. Binding was Ca(2+)-dependent and inhibitable with d-mannose. A fusion protein of the mannose receptor containing carbohydrate recognition domains 4-7 and a full-length soluble form of the mannose receptor containing all domains external to the transmembrane region both displayed very similar binding specificities toward bacterial polysaccharides, suggesting that domains 4-7 are sufficient for recognition of these structures. Surprisingly, no direct correlation could be made between polysaccharide structure and binding to the mannose receptor, suggesting that polysaccharide conformation may play an important role in recognition. The full-length soluble form of the mannose receptor was able to bind simultaneously both polysaccharide via the carbohydrate recognition domains and sulfated oligosaccharide via the cysteine-rich domain. The possible involvement of the mannose receptor, either cell surface or soluble, in the innate and adaptive immune responses to bacterial polysaccharides is discussed.     

Antibody recognition of bacterial surfaces and extracellular polysaccharides

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细菌荚膜多糖的化学结构

荚膜是一些细菌所具有的表层结构,与多种疾病有着密切联系。细菌荚膜多糖不仅结构复杂,而且在免疫活性方面发挥着重要的作用。同一种细菌根据其荚膜多糖的抗原性不同可分为不同的血清型,不同血清型细菌荚膜多糖的化学结构也存在差异。以荚膜多糖为基础的疫苗正在积极研究开发当中,对不同致病细菌荚膜多糖具体化学结构的掌握是疫苗得到许可的必备条件之一。本文对致病细菌荚膜多糖的化学结构进行了归纳和总结,以期为荚膜多糖的化学结构研究和疫苗开发提供参考。     

Role of water-soluble polysaccharides in bacterial cellulose production

Acetobacter xylinum BPR2001 produces water-insoluble bacterial cellulose (BC) and a water-soluble polysaccharide called acetan in corn steep liquor-fructose medium. Acetobacter xylinum EP1, which is incapable of acetan production was derived by disrupting the aceA gene of BPR2001. The BC production by EP1 (2.88 g/L) was lower than that by BPR2001 (4.6 g/L) in baffled-flask culture. When purified acetan or agar was added to the medium from the start of cultivation, the BC production by EP1 was enhanced and the final BC yield of EP1 was almost the same as that of BPR2001. A similar improvement of BC production by EP1 by the addition of agar was also confirmed by cultivation in a 50-L airlift reactor. From these results, the role of acetan in BC production is associated with the increase in the viscosity of the culture medium which may hinder coagulation of BC and cells in the culture, thereby accelerating the growth of BPR2001 and BC production by BPR2001.     

Assimilation of polysaccharides and glucose by major bacterial groups in the Delaware Estuary

The contribution of major bacterial groups to the assimilation of extracellular polymeric substances (EPS) and glucose in the Delaware Estuary was assessed using microautoradiography and fluorescence in situ hybridization. Bacterial groups contributed to EPS and glucose assimilation in part according to their distribution in the estuary. Abundance of the phylogenetic groups explained 35% and 55% of the variation in EPS and glucose assimilation, respectively. Actinobacteria contributed 70% to glucose assimilation in freshwater, while Alphaproteobacteria assimilated 60% of this compound in saline water. In contrast, various bacterial groups dominated the assimilation of EPS. Actinobacteria and Betaproteobacteria contributed the most in the freshwater section, whereas Cytophaga-like bacteria and Alpha- and Gammaproteobacteria participated in EPS assimilation in the lower part of the estuary. In addition, we examined the fraction of bacteria in each group that assimilated glucose or EPS. Overall, the fraction of bacteria in all groups that assimilated glucose was higher than the fraction that assimilated EPS (15 to 30% versus 5 to 20%, respectively). We found no correlation between the relative abundance of a group in the estuary and the fraction of bacteria actively assimilating glucose or EPS; the more active groups were often less abundant. Our results imply that the bacterial community in the Delaware Estuary is not controlled solely by "bottom-up" factors such as dissolved organic matter.     

Enhanced bioaccumulation of heavy metals by bacterial cells displaying synthetic phytochelatins

A novel strategy using synthetic phytochelatins is described for the purpose of developing microbial agents for enhanced bioaccumulation of toxic metals. Synthetic genes encoding for several metal-chelating phytochelatin analogs (Glu-Cys)(n)Gly (EC8 (n = 8), EC11 (n = 11), and EC20 (n = 20)) were synthesized, linked to a lpp-ompA fusion gene, and displayed on the surface of E. coli. For comparison, EC20 was also expressed periplasmically as a fusion with the maltose-binding protein (MBP-EC20). Purified MBP-EC20 was shown to accumulate more Cd(2+) per peptide than typical mammalian metallothioneins with a stoichiometry of 10 Cd(2+)/peptide. Cells displaying synthetic phytochelatins exhibited chain-length dependent increase in metal accumulation. For example, 18 nmoles of Cd(2+)/mg dry cells were accumulated by cells displaying EC8, whereas cells exhibiting EC20 accumulated a maximum of 60 nmoles of Cd(2+)/mg dry cells. Moreover, cells with surface-expressed EC20 accumulated twice the amount of Cd(2+) as cells expressing EC20 periplasmically. The ability to genetically engineer ECs with precisely defined chain length could provide an attractive strategy for developing high-affinity bioadsorbents suitable for heavy metal removal.