The Influence Of Mercury Exposure On The Pathogenicity Of Aspergillus Versicolor

With the speeding up of the industrial and agricultural development, Mercury and other heavy metals pollution has become a topical subject in the world, which seriously threatened wildlife.Mercury （Hg） is one of the most toxic heavy metals in the environment. Mercury can enter the animals through a variety of ways to damage animal health. Since the level of environmental mercury exposure is mostly at low level and endangering animals’ health by forms such as immunosuppression, so sometimes Mercury toxicity is hidden and the process that is usually slow and gradual,.Researchs showed that the habitat changing could influence the immunity of animals. Mercury and other contaminants exposure can lead to not only higher infection rate of pathogenic microorganisms, but also increased the incidence of some conditional pathogenic microorganisms. In current background with heavy metal pollution more and more serious, More and more new fungal diseases emerge and their morbidity are higher. Aspergillus versicolor is one of the poisonous fungi slowly coming into focus. Aspergillus versicolor and its toxic metabolism causes disease in many animals including Bombyx mori Linnaeus, rat, Gallus domestiaus, Cercopithecus aethiops and so on.Contaminants exposure has already been a huge threat to wildlife. The amphibians as the indicator of environmental degradation are experiencing a global recession. There are many factors leading to population decline of amphibians. The spreading of pathogenic fungi severely damaged the amphibian populations, meanwhile heavy metals and pesticide residues also complicated the healthy situation of amphibians. This study aims to explore The influence of mercury exposure on the pathogenicity of Aspergillus versicolor.There are many Chinese endemic amphibians in Hunan, but mercury pollution in Hunan province is increasingly serious in recent years, especially in the Dongting Lake and other water systems, which had a serious effect on the amphibians in Hunan.Hunan province is significant important for ecological safety of the central China.connects eastern coastal provinces to inland provinces. It located in the region of middle reach of Yangtze River. There are many rivers in Hunan province, and the second largest fresh water lake in China, Dongting Lake, is also in it. Hunan province has continental humid subtropical monsoon climate,so it is suitable for a variety of fungi survival.Therefore,400 Pelophylax nigromaculatus were sampled in the twelve sampling areas around the Dongting Lake and in some important waters in Hunan for epidemiological investigation of skin fungi using molecular biology identification methods; preliminary genetic analysis was carried out on the obtained strains; And the effect of mercuric chloride on the pathogenicity of skin fungi isolated from Pelophylax nigromaculatus was detected.Survey results showed there were Aspergillus versicolor found on the Pelophylax nigromaculatus in sampling areas of Hunan province, and there were other fungi of 7 genus detected in the skin of samples:Penicillium spp., Cladosporium spp., Chaetomium spp., Yarrowia spp. ,Debaryomyces spp., Candida spp., Trichosporon spp., Aspergillus spp.. The dominant genus is Penicillium spp. （about 11%）.When larvae exposed to the low concentration of HgCl₂, the disease-resistant ability of Pelophylax nigromaculatus was decreased; and at the same time infection ability of A. versicolor for Pelophylax nigromaculatus was increased, by this time A. versicolor is conditioned pathogen fungus. When Pelophylax nigromaculatus was infected with A. versicolor, not only the damages in liver and kidney can be seen, but also the death of part of larvae was recorded.