Enzyme activities and internal bacteria of saprophagous soil mites (Acari: Oribatida, Acaridida)

Abstract

Several saprophagous mites (Acari: Oribatida, Acaridida) were tested for chitinolytic activity of their enzymes. These mites were sampled in the field (Damaeus, Belba, Metabelba) or obtained from cultures (Archegozetes, Scheloribates, Tyrophagus). Mites were tested on several fungi from a fungal collection (Alternaria, Fusarium), as well as fungi isolated from mite-rearing boxes (Penicillium, Mucor). These tests involved (1) light and fluorescence microscopy of adequately stained mites to detect internal, but extra-intestinal, bacteria, (2) staining of mite homogenates to detect chitinase activity, and (3) plating of mite homogenates and purification to obtain pure cultures of the internal bacteria for identification. Mycophagy of the mites was classified into three types: (1) grazing and digesting fragments of fungi, including their chitinous cell wall, as proven by chitinase activity, (2) cutting and ingesting hyphae, but digesting only the cell content (no chitinase activity), and (3) piercing mycelium and sucking its content (chitinolytic bacteria were plated from the homogenate of those mites, but no chitinase activity).