Objectives: The influence of abiotic factors of water which may affect Artemesia annua (A. annua) efficiency as a disinfectant is not clearly elucidated. This study aimed to assess the potential effects of various water pH values of the infusion of A. annua leaves extract on some bacteria of hygiene and sanitary evaluation. Methodology and Results: A. annua leaves were collected in Bangante (West region, Cameroon) and bacteria were isolated from the surface water (lotic hydrosystems) in Yaoundé (Cameroon, Central Africa). The bacteria used were S. paratyphi, S. aureus and E. coli. Experiments were carried out in aquatic microcosms under dark conditions. The pH values considered were 4, 5, 6, 7, 8 and 9. These values were adjusted using diluted HCl and NaOH. The results showed the temporal changes of cell abundance from one bacteria species to another with respect to the pH value in one hand, and also with respect to the number of cell species in solution on the other hand. In monospecific culture condition, the extract of A. annua seemed to appear as a source of carbon and energy for bacteria growth. In mixed cultures the influence of pH in the presence of the extract of A. annua in the dark seemed to foster trophic relations among bacteria in some cases and stimulate the production of inhibitory substances in other cases. Conclusions and application of findings: Molecules contained in the extract of A. annua were potentially implicated in the physical and chemical changes of the medium, enabling the cell growth observed. A. annua extract did not have a significant bacterial inhibitory property in the water in the darkness. Although A. annua extract is often used as antibacterial component, it should not be used in the bacteriological treatment of drinking water under dark condition whether the water pH is acidic, neutral or alkaline.

Objectives:The influence of abiotic factors of water which may affect Artemesia annua (A. annua) efficiency as a disinfectant is not clearly elucidated. This study aimed to assess the potential effects of various water pH values of the infusion of A. annua leaves extract on some bacteria of hygiene and sanitary evaluation. Methodology and Results: A. annua leaves were collected in Bangante (West region, Cameroon) and bacteria were isolated from the surface water (lotic hydrosystems) in Yaoundé (Cameroon, Central Africa). The bacteria used were S. paratyphi, S. aureus and E. coli. Experiments were carried out in aquatic microcosms under dark conditions. The pH values considered were 4, 5, 6, 7, 8 and 9. These values were adjusted using diluted HCl and NaOH. The results showed the temporal changes of cell abundance from one bacteria species to another with respect to the pH value in one hand, and also with respect to the number of cell species in solution on the other hand. In monospecific culture condition, the extract of A. annua seemed to appear as a source of carbon and energy for bacteria growth. In mixed cultures the influence of pH in the presence of the extract of A. annua in the dark seemed to foster trophic relations among bacteria in some cases and stimulate the production of inhibitory substances in other cases. Conclusions and application of findings: Molecules contained in the extract of A. annua were potentially implicated in the physical and chemical changes of the medium, enabling the cell growth observed. A. annua extract did not have a significant bacterial inhibitory property in the water in the darkness. Although A. annua extract is often used as antibacterial component, it should not be used in the bacteriological treatment of drinking water under dark condition whether the water pH is acidic, neutral or alkaline.