Activated sludge samples from pilot plants using different processes for enhanced biological phosphorus removal were investigated for the occurrence of polyphosphate‐accumulating bacteria. All samples showed a direct correlation between the relative number of phosphate‐accumulating bacteria and phosphate uptake. Various species of bacteria with polyphosphate granules were found in sludge flocs, but in every case Acinetobacter‐like cells formed part or the main part of the polyphosphate‐accumulating bacterial population. The spectrum of the bacteria with stored polyphosphates varied, depending on the sewage composition on the one hand and on the processes used for phosphorus removal on the other hand.
Polyphosphate-accumulating gram-negative bacteria were isolated from different anaerobic-aerobic activated sludge systems with diverse processes for enhanced biological phosphorus (P) elimination. Of 22 isolates, 10 were allocated to the genus Acinetobacter by using multiple-test systems and soluble protein and polyamine patterns. As diaminopropane (DAP) appears to be the characteristic main polyamine compound produced by Acinetobacter spp., it was used as a biomarker for the genus. The high DAP contents of representative samples from municipal wastes with enhanced biological P elimination indicated that Acinetobacter spp. can be dominant organisms in sewage treatment plants with low organic loading and nitrification and denitrification steps. Contrary to accepted opinion, sludge from treatment plants with efficient P removal and high organic loading had a low DAP content, indicating that bacteria other than Acinetobacter spp. are responsible for enhanced biological P elimination in these plants.
A method for extraction of microbial populations from wood samples was worked out which gave good recovery of both aerobic and anaerobic microorganisms in agar shake dilution and plating enumerations. This method was applied to the quantification of microbial populations in three European white firs (Abies alba Mill.) which were afflicted with the European fir disease. Low numbers of aerobic microorganisms (102−104 colony‐ forming units (cfu) per g fresh tissue) were detected in sapwood irrespective of the degree of affliction. Anaerobic bacteria were usually 1–2 orders of magnitude less frequent. Wetwood of highly diseased firs contained significantly higher numbers of aerobic microorganisms (105−107), whereas the number of anaerobes was not enhanced significantly. Among the prevalent aerobic microorganisms in wetwood were Protaminobacter, Pseudomonas strains, and a yeast. In anaerobic counts from wetwood, Klebsiella and Vibrio strains predominated. The sapwood contained Bacillus, Beijerinckia, Staphylococcus, and Clostridium spp. High numbers of aerobic microorganisms were also detected in the roots and lower stem of a diseased vine plant (Vitis vinifera L.). The importance of microbial populations in wetwood formation and disease expression is discussed.
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