Bacterial commensalism

The optimum temperature varies widely from species to species but in general the common moulds will grow better at 22-25 °C than most human pathogenic and commensal bacteria. It is customary, therefore, to incubate mould cultures at lower temperatures than bacterial cultures. 

Municipal waste water treatment plants receive daily considerable amounts of non-metabolized antibiotics and metabolites thereof, as well as other environmental pollutants. Moreover, domestic waste water is a complex mixture of human commensal and environmental bacteria, which get in contact with considerable amounts of antimicrobial agents and other substances with unknown effects on bacterial metabolism and microbial communities [38,54-57]. The free movement of bacteria between different environmental niches and the easiness with which bacteria become adapted to new conditions contribute to a rapid dissemination of antibiotic... 

Commensal bacteria, capable of colonizing mucosal surfaces, which are genetically engineered to express viral, bacterial, or eukaryotic antigens to produce an immune response... 

A range of different vaccine vectors has been developed over time to provoke an immune response within the body [127,142], However, it has only been comparatively recently that they have been applied to inducing mucosal immunity within the uterovaginal tract. The general vector platforms that have been used include attenuated viruses, live viruses, commensal bacteria, DNA vectors, and protein subunit/peptide or virus-like particles (Table 21.9). The choice of vector is dependent on a number of factors such as the pathogenic virus and bacterial type and the length of duration of immunity required. 

Symbiobacterium thermophilum is an uncultivable bacterium isolated from compost that depends on microbial commensalism. The 16S ribosomal DNA-based phylogeny suggests that this bacterium belongs to an unknown taxon in the Gram-positive bacterial cluster (Ueda et al., 2004), low G + C Gram-positive bacteria... 

Antimicrobial action usually depends on the inhibition of biochemical events that exist in or are essential to the bacterial pathogen but not the host animal. Unfortunately, the action of antimicrobial agents is not selective for pathogenic microorganisms and the balance between the commensal flora can be seriously disturbed, particularly in the colon of horses (macrolides, lincosamides and, paren ter ally administered doxycycline). 

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