Study On Biodegradation Of Anthraquinone Compounds By Sphingomonas Xenophaga QYY And Rhodococcus Pyridinivorans GF3

Bacteria, which have been isolated, can only slowly degrade several anthraquinone compounds. Moreover, the degradation products of these anthraquinone compounds are easily auto-oxidized under aerobic conditions. In the present study, the effects of additional nutrients on anthraquinone compounds degradation by Sphingomonas xenophaga QYY and accelerating mechanism were studied. Meanwhile, a novel bacterium capable of degrading several anthraquinone compounds was isolated. The growth characteristics of the isolated Rhodococcus pyridinivorans GF3, its ability to degrade anthraquinone compounds and1-aminoanthraquinone-2-sulfonic acid (ASA-2) degradation pathway were investigated.Nutrients amendment could enhance the bio-decolorization of ASA-2and1-amino-4-bromoanthraquinone-2-sulfonic acid (ABSA) by strain QYY. Yeast extract and peptone increased the bio-decolorization rates of ASA-2and ABSA. Glucose, fructose, sucrose and casamino acids could promote ASA-2and ABSA bio-decolorization. Among these nutrients,glucose showed the most significant influence on ASA-2and ABSA decolorization, with76.7%and50.8%increases, respectively. Additional urea, ammonium nitrate and vitamins did not promote the bio-decolorization of the two anthraquinone compounds. Further studies found that L-leucine, L-glutamic acid, L-proline L-cystine, L-aspartate and L-phenylalanine could accelerate ASA-2and ABSA bio-decolorization. Especially, in the presence of L-proline, the decolorization efficiencies of ASA-2and ABSA increased79.9%and67.3%, respectively. Crude enzymes from celll extracts were obtained by sonication and ultracentrifugation, then used for studying the relationship between the decolorization enzyme(s) activities and L-proline. The experiments showed that ASA-2and ABSA decolorization enzyme(s) was located in cellular membranes. Instead of NADH, L-proline could be directly invovled in ASA-2and ABSA decolorization by cellular membranes.A new strain GF3capable of degrading anthraquinone compounds was isolated under aerobic conditions. The16S rDNA sequence of strain GF3shared100%similarity with Rhodococcus pyridinivorans NR025033and KF38149. The16S rDNA sequence of strain GF3was submitted to GenBank with the number KF953541.The characteristics of strain GF3growth and ASA-2bio-decolorization were investigated and the cleavage process of anthraquinone ring was analyzed. The optimal conditions for strain GF3growth and ASA-2bio-decolorization process were as follows:pH=7.0,30℃ and150r/min.. Additional yeast extract as an carbon source could significantly enhance the growth of strain GF3and ASA-2bio-decolorization. Additional nitrogen sources could promote ASA-2decolorization in different levels. Among these nitrogen sources, urea and ammonium nitrate showed the most significant influence on ASA-2bio-decolorization, with49.1%and47.1%increases, respectively. Among the tested trace elements, ferric trichloride could accelerate ASA-2bio-decolorization with7.4%increase. Strain GF3can degrade not only ASA-2, but also other anthraquinone compounds including ABSA, anthraquinone-2-carboxylic acid and anthraquinone-2-sulfonic acid. However, strain GF3can not degrade anthraquinone-2,6-disulfonic acid. Additionally, during ASA-2bio-decolorization, the removal percentage of TOC reached60.6%, indicating the cleavage of the anthraquinone ring of ASA-2. HPLC-MASS spectra analysis showed that the main decolorization products were proposed to be2-amino-3-carboxyl benzenesulfonic acid and2-amino-4-carboxyl benzenesulfonic acid.