Preparation of pH 3.0 agar plate, enumeration of acid-tolerant, and Al-resistant microorganisms in acid soils

We attempted to prepare an agar plate containing Al under the acid conditions (pH 3.0) to count the number of colonies of Al-resistant microorganisms and isolate them. As a result, Al-resistant microorganisms were isolated from the tea garden soils and identified. 1. Agar could be solidified when the culture medium solution (pH 3.0), Al2(SO4)3 solution (pH 3.0), and agar solution were mixed after autoclaving separately.2. The number of Al-resistant microorganisms was largest in the strong acid tea garden soil, followed by the forest soil and smallest in the upland soil. In particular, the number of Al-resistant microorganisms (Al 100 mM in agar medium) accounted for 12.5% of the number of total microorganisms, suggesting that the accumulation of Al-resistant microorganisms increased when the soil pH decreased.3. Fungi accounted for most of the high Al-resistant microorganisms.4. About half of the acid-tolerant fungi (grown at pH 3.0) from the tea garden soils consisted of high Al-resistant microorganisms (Al; 100 mM).5. Eight strains Emericellopsis sp., Paecilomyces lilacinus, Moritierella ramanniana var. angulispora, Sprothrix inflata, Penicillium glabrum, Metarhizum anisopliae, Chaetospharia inaeqalis, and Aspergillus fumiatus were identified as Al-resistant fungi from the tea garden soils.