Growth and interaction mechanism of multi-strain biofouling under different nutrient levels

Heat pump system is an effective method for heat recovery of a treated sewage source, but biofouling on heat exchanger is still a problem to be solved, and may affect seriously efficiency and security of the system. By long term monitoring and 16S rRNA identification, two major bacteria genus, Bacillus sp. and Aeromonas sp., were selected for multi-strain biofouling experiment of a model fluid in laboratory. By the experiment of foul growth performed on a purpose made channel at various bacteria ratios and nutrient levels, the regular patterns of single and mixed microbe growth of Bacillus sp. and Aeromonas sp. were revealed, their synergy and inhibition interaction summarized, and the effect of nutrient levels on their growth mechanism and interaction also investigated. The results indicated that the Bacillus sp. has strong ability in biofouling, in high multiple rates, and high tolerance to poor nutrient level. The biofouling of Aeromonas sp. is weak relatively, but high secretion rate that may help for the synergy growth with Bacillus sp. Their synergy and inhibition interactions co-exist and dominate in turn under different growth stage and condition.