Open AccessAdaptation and population dynamics of Azotobacter vinelandii during aerobic biological treatment of olive‐mill wastewater
Author(s) -
Ehaliotis Constantinos,
Papadopoulou Kalliopi,
Kotsou Maria,
Mari Ioanna,
Balis Constantinos
Publication year - 1999
Publication title -
fems microbiology ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.377
H-Index - 155
eISSN - 1574-6941
pISSN - 0168-6496
DOI - 10.1111/j.1574-6941.1999.tb00658.x
Subject(s) - azotobacter vinelandii , biology , population , wastewater , phytotoxicity , azotobacteraceae , aeration , bioreactor , microbiology and biotechnology , food science , botany , nitrogen fixation , environmental engineering , ecology , nitrogenase , bacteria , environmental science , sociology , genetics , demography
Olive‐mill wastewater (OMW) has a high organic and polyphenol content and is resistant to biodegradation. Its disposal leads to a major environmental pollution problem in the Mediterranean basin. The detoxification of OMW following inoculation with Azotobacter vinelandii (strain A) was performed for two successive 5‐day‐period cycles in an aerobic, biowheel‐type reactor, under non‐sterile conditions. The phytotoxicity of the processed product was reduced by over 90% at the end of both cycles. To exclusively monitor the A. vinelandii population in the reactor a most probable number‐PCR approach was employed and applied daily to serial dilutions of total DNA extracted from reactor samples. PCR sensitivity was independent of the presence of OMW or non‐target DNA. The A. vinelandii population dynamics were successfully monitored, showing an initial adaptation period, followed by a sharp population maximum on the fourth day of both cycles (1.6×10 8 and 9.6×10 7 cells ml −1 respectively), after a major phytotoxicity decline. N 2 fixation rates were estimated using the acetylene reduction assay and reached a peak during the first 1–2 days of each cycle (36 and 29 nmol C 2 H 2 ml −1 h −1 respectively). The data are consistent with an initial physiological adaptation phase, where the presence of phenolic compounds limits A. vinelandii growth but stimulates N 2 fixation, followed by a rapid growth phase as phytotoxicity declines.