FORMATION OF HEMOPROTEIN-CONTAINING EXTRACELLULAR STRUCTURES BY BACTERIA

Alcaligenes sp. strain d(2) isolated from lake silt contains extracell ular formations, red granules, structurally bound with cells and peas balloons. The granules are heterogeneous in size and shape; among them there are submicroscopic and large (up to 3 - 5 mu m thick or larger) granules. They are clearly discernable in a light (especially interfe rence) microscope and appear as red bodies. Element analysis with an a nalytical electron microscope revealed an increased content of iron, c alcium, and silicon in red granules. Under UV light, the granules exhi bit either red or green fluorescence. Spectrophotometric investigation s showed that extracts of purified fractions of red granules obtained using phosphate buffer + 0.1% Triton X-100 contained a pigment having absorption peaks at 405, 506, 541, 578, 633, and 672 nm. The spectrum of dithionite-reduce:d form is typical of hemoproteins and has absorpt ion peaks at 419, 526, and 558 nm. Electrophoresis in a PAAG gradient showed the molecular weight of one of the hemoprotein pigments extract ed from red granules to be about 66 kDa. From the data obtained, it is inferred that the composition of red granules includes hemoproteins. A possible function of red granules and gas balloons is discussed.