Degradation of polycyclic aromatic hydrocarbons with three to seven aromatic rings by higher fungi in sterile and unsterile soils.

Seven commercial 3- to 7-ring (R) polycyclic aromatic hydrocarbons (PAH) as well as PAH derived from lignite tar were spiked into 3 soils (0.8 to 9.7% of organic carbon). The disappearance of the original PAH was determined for the freshly spiked soils, for soils incubated for up to 287 d with their indigenous microflora, and for autoclaved, unsterile and pasteurized soils inoculated with basidiomycetous and ascomycetous fungi. Three to 12 d after spiking, 22 to 38% of the PAH could no longer be recovered from the soils. At 287 d, 88.5 to 92.7%, 83.4 to 87.4%, and 22.0 to 42.1% of the 3-, 4-, and 5- to 7-R PAH, respectively, had disappeared from the unsterile, uninoculated soils. In 2 organic-rich sterile soils, the groups of wood- and straw-degrading, terricolous, and ectomycorrhizal fungi reduced the concentration of 5 PAH by 12.6, 37.9, and 9.4% in 287 d. Five- to 7-R PAH were degraded as efficiently as most of the 3- to 4-R PAH. In organic-rich unsterile soils inoculated with wood- and straw-degrading fungi, the degradation of 3- to 4-R PAH was not accelerated by the presence of fungi. The 5- to 7-R PAH, which were not attacked by bacteria, were degraded by fungi to 29 to 42% in optimum combinations of fungal species and soil type. In organic-poor unsterile soil, these same fungi delayed the net degradation of PAH possibly for 2 reasons. Mycelia of Pleurotus killed most of the indigenous soil bacteria expected to take part in the degradation of PAH, whereas those of Hypholoma and Stropharia promoted the development of opportunistic bacteria in the soil, which must not necessarily be PAH degraders. Contemporarily, the contribution of the fungi themselves to PAH degradation may be negligible in the absence of soil organic matter due to the lower production of ligninolytic enzymes. It is concluded that fungi degrade PAH irrespective of their molecular size in organic-rich and wood chip-amended soils which promote fungal oxidative enzyme production.

Influence of beta-carotene supplementation on carotene content of ovaries of heifers.

Carotene is stored as a tissue reserve in the corpus luteum. With different carotene supplementations in heifers (0, 100, 200 and 300 mg/animal and day) it could be clearly seen that the carotene concentration in the corpus luteum (2.3, 27, 50 and 81 micrograms/g) was directly dependent on it. On the other hand, the weight of corpus luteum (3.8 to 4.6 g) was not influenced (P greater than 0.05) by carotene supplementation. Apart from corpus luteum carotene was also stored in orange coloured pigment corpuscles of ovary. The carotene concentration of the pigments was 6 to 70 times higher (158, 150, 334 and 487 micrograms/g) than in the corpus luteum. Weights of the pigments rose with increased carotene doses. However, the weights amounted to merely 4 to 11% of the corpus luteum's mass. The amount of carotene in corpus lutea of animals added with carotene contained was higher than that of pigments. Further investigations are necessary to characterize the physiological importance of the pigment corpuscles.