Yeast/bacteria interactions

Host Cell Impurities Various organisms have been used to produce recombinant proteins yeast, bacteria (e.g., E. coli), insect cells, and mammalian cells such as Chinese hamster ovary (CHO) cells. During the purification process, some HCPs can copurify with the protein product. Because of the specificity of the antigen-antibody interaction, an ELISA can be used to detect and quantitate the contaminating HCPs. Detecting host impurities is important for quality process control as well as for product safety issues. The intent is to avoid unsafe levels of residual HCPs which might lead to adverse reactions.11... 

The easiest cells to grow are microbes that live independently in their natural environment. These include bacteria, yeasts, and molds. The hardest are the cells extracted from higher order plants and animals since they normally rely on complex interactions with other cells in the parent organism. Bacteria and yeasts are single-celled. Molds are multicelled but have relatively simple structures and nutritional requirements. 

Christensen et al. [93] successfully obtained a divalent cluster having -600-1500 enhanced binding properties. We have also demonstrated that dendritic mannosides such as 66 (Scheme 11) can provide up to 100-fold higher affinity (on a per-mannoside basis) when used to inhibit the binding of plant lectins (Concanavalin A and pea lectins) to yeast mannan [85]. As these interactions are at the origin of host infections by fimbriated bacteria, mannoside dendrimers can form the basis of novel antiadhesin molecules. 

Of the particulate stimuli certain ones are far more active when they are coated with proteins from serum (opsonized) than when they are not. However, others like latex beads elicit formation of Oj" by PMNs without opsonization DeChatelet et al. found that the production of O by PMNs from man and rabbit was stimulated by opsonized but not unopsonized zymosan (fragments of yeast cell walls). Bacteria alone were found to stimulate the formation of O but in the presence of serum bacteria stimulated the formation of O7 three fold However, the stimulatory effect of bacteria appeared to be caused by changes which the bacteria produced by an interaction with constitutents of serum, because serum itself after exposure to the bacteria stimulated production of O by PMNs. The active component from serum was heat sensitive (100°) and not sedimentable at 105,000 g. Whether this material was derived from the components of serum or from the bacteria is not clear but may have been a protein of the complement system. 

Gobbetti, M. 1998. The sourdough microflora Interactions between lactic acid bacteria and yeast. Trends Food Sci Technol 9 267-274. 

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