How do the carbon and nitrogen sources affect the synthesis of ß-(1,3/1,6)-glucan, its structure and the susceptibility of Candida utilis yeast cells to immunolabelling with ß-(1,3)-glucan monoclonal antibodies?

BACKGROUND: The need to limit antibiotic therapy due to the spreading resistance of pathogenic microorganisms to these medicinal substances stimulates research on new therapeutic agents, including the treatment and prevention of animal diseases. This is one of the goals of the European Green Deal and the Farm-To-Fork strategy. Yeast biomass with an appropriate composition and exposure of cell wall polysaccharides could constitute a functional feed additive in precision animal nutrition, naturally stimulating the immune system to fight infections. RESULTS: The results of the research carried out in this study showed that the composition of Candida utilis ATCC 9950 yeast biomass differed depending on growth medium, considering especially the content of ß-(1,3/1,6)-glucan, α-glucan, and trehalose. The highest ß-(1,3/1,6)-glucan content was observed after cultivation in deproteinated potato juice water (DPJW) as a nitrogen source and glycerol as a carbon source. Isolation of the polysaccharide from yeast biomass confirmed the highest yield of ß-(1,3/1,6)-glucan after cultivation in indicated medium. The differences in the susceptibility of ß-(1,3)-glucan localized in cells to interaction with specific ß-(1,3)-glucan antibody was noted depending on the culture conditions. The polymer in cells from the DPJW supplemented with glycerol and galactose were labelled with monoclonal antibodies with highest intensity, interestingly being less susceptible to such an interaction after cell multiplication in medium with glycerol as carbon source and yeast extract plus peptone as a nitrogen source. CONCLUSIONS: Obtained results confirmed differences in the structure of the ß-(1,3/1,6)-glucan polymers considering side-chain length and branching frequency, as well as in quantity of ß-(1,3)- and ß-(1,6)-chains, however, no visible relationship was observed between the structural characteristics of the isolated polymers and its susceptibility to immunolabeling in whole cells. Presumably, other outer surface components and molecules can mask, shield, protect, or hide epitopes from antibodies. ß-(1,3)-Glucan was more intensely recognized by monoclonal antibody in cells with lower trehalose and glycogen content. This suggests the need to cultivate yeast biomass under appropriate conditions to fulfil possible therapeutic functions. However, our in vitro findings should be confirmed in further studies using tissue or animal models.

Molar-mass-dependent antibacterial activity of cationic dextran derivatives against resistant nosocomial pathogens.

The rise of various multidrug-resistant bacteria has created a need for new biocompatible and biodegradable antibacterial compounds. Cationic polysaccharides are promising candidates for this role. Therefore, cationic derivatives of commercial dextrans with molar masses of 11 kDa, 76 kDa, 411 kDa, and 1500-2500 kDa and various degrees of substitution (DSQ 0.34-0.52) were prepared and their antimicrobial properties against four gram-negative nosocomial bacteria were tested. As expected, a higher DSQ led to higher efficiency. The best antimicrobial properties were found for derivatives of 411 kDa, followed by 76 kDa and 1500-2000 kDa dextrans. This indicates that there is a certain optimum molar mass with the best antimicrobial properties. However, as molar mass increased, the biocompatibility of cationic dextran steadily decreased, with increased hemagglutination and toxicity being seen for human cells. The derivatives of 76 kDa dextran with higher DSQ (0.40-0.52) were the best antimicrobial agents suitable for further clinical testing.

Potential pathogenicity and antibiotic resistance of aquatic Vibrio isolates from freshwater in Slovakia.

This study aimed to evaluate the potential pathogenicity and antibiotic resistance of 31 environmental Vibrio isolates obtained from surface water in southern and eastern Slovakia. Isolates were identified as Vibrio cholerae non-O1/non-O139 and Vibrio metschnikovii by biochemical tests, MALDI biotyping, and 16S RNA gene sequencing. Analysis of the susceptibility to 13 antibacterial agents showed susceptibility of all isolates to ciprofloxacin, trimethoprim/sulfamethoxazole, chloramphenicol, gentamicin, imipenem, tetracyclin, and doxycycline. We recorded high rates of resistance to ß-lactams and streptomycin. Investigation of antibiotic resistance showed five different antibiotic profiles with resistance to antibacterials from three classes, but no multidrug resistance was observed. The investigation of the pathogenic potential of V. cholerae isolates showed that neither the cholera toxin coding gene ctxA nor the genes zot (zonula occludens toxin), ace (accessory cholera toxin), and tcpA (toxin-coregulated pilus) were present in any of 31 isolated samples. Gene ompU (outer membrane protein) was confirmed in 80% and central regulatory protein-coding gene toxR in 71% of V. cholerae isolates, respectively. A high prevalence of the hemolysin coding gene hlyA in all V. cholerae was observed. The data point toward the importance of systematic monitoring and comparative studies of potentially pathogenic vibrios in European countries.