Removal of xylene by a mixed culture of Pseudomonas sp. NBM21 and Rhodococcus sp. BTO62 in biofilter.

Xylene (a mixture of o-, m-, p-xylenes and ethylbenzene) gas removal was conducted in the a biofilter inoculated with a mixture of the m- and p-xylene-degraders, Pseudomonas sp. NBM21 and an o-xylene degrader, Rhodococcus sp. BTO62 under non-sterile conditions at 20 degrees C. Elimination capacities of o-, m-, and p-xylenes obtained were 180 g/m(3)/h at 20 degrees C and 100 g/m(3)/h at 10 degrees C, which were significantly higher than the 60-78 g/m(3)/h of previously reported biofilters, indicating that the two bacteria inoculated exhibited an almost total ability to remove xylene although only present in low numbers in the biofilter. In the sterile biofilter, carbon mass balance showed that 11.6% of the removed xylene was converted to cell mass. Among the xylene components, o-xylene was the most resistant to microbial degradation in spite of the low component ratio.

Degradation pathway of an anthraquinone dye catalyzed by a unique peroxidase DyP from Thanatephorus cucumeris Dec 1.

The reactants produced by action of a purified unique dye-decolorizing peroxidase, DyP, on a commercial anthraquinone dye, Reactive Blue 5, were investigated using electrospray ionization mass spectrometry (ESI-MS), thin-layer chromatography (TLC), and (1)H- and (13)C- nuclear magnetic resonance (NMR). The results of ESI-MS analysis showed that phthalic acid, a Product 2 (molecular weight 472.5), and a Product 3 (molecular weight 301.5), were produced. Product 2 and Product 3 were generated by usual peroxidase reaction, whereas phthalic acid was generated by hydrolase- or oxygenase-catalyzed reaction. One potential associated product, o-aminobenzene sulfonic acid, was found to be converted to 2,2'-disulfonyl azobenzene by ESI-MS and NMR analyses. From these results, we propose, for the first time, the degradation pathway of an anthraquinone dye by the enzyme DyP.

Efficient dye decolorization and production of dye decolorizing enzymes by the basidiomycete Thanatephorus cucumeris Dec 1 in a liquid and solid hybrid culture.

Thanatephorus cucumeris Dec 1, a basidiomycete, is a promising decomposer of several xenobiotics. Air-membrane surface bioreactor culture (AMS culture), a hybrid between solid-state and submerged culture, was used for Dec 1 growth. The optimum temperature for AMS culture (25 degrees C) was lower than that for submerged culture (30 degrees C). Fungal growth was almost the same in AMS culture as in submerged culture at optimum temperatures. However, protein secretion, dye decolorizing peroxidase (DyP) activity, and aryl alcohol oxidase activity, were 18-, 233-, and 36.5-fold higher in AMS culture than in submerged culture, respectively, indicating that AMS culture of Dec 1 was superior to submerged culture. In in vivo dye decolorization tests, 13 of 16 dyes were decolorized by more than 90% within 10 days. Interestingly, under AMS culture, a biofilm was formed; biofilm formation was not, however, essential for DyP and manganese dependent peroxidase (MnP) activities. Although the correlation between DyP activity and water activity was unclear, MnP activity seemed to increase in activity with decreasing water activity, even when no biofilm formation was observed.

Microbial analysis of a composted product of marine animal resources and isolation of bacteria antagonistic to a plant pathogen from the compost.

A composting product of marine animal resources has been used as a fertilizer and a soil conditioner in Japan. This compost was produced by a repeated fed-batch fermentation system with three successive aerobic bioreactors. Composting temperature reached about 75 degrees C without heating. The bacterial diversity in this compost was investigated by denaturing gradient gel electrophoresis (DGGE) and sequence determination of the V3 region in the 16S rRNA genes. The sequence analysis showed that a majority of retrieved sequences corresponded to those of Bacillaceae, and we frequently found sequences similar to the 16S rDNA sequences of Bacillus thermocloacae and Bacillus thermoamylovorans. In addition, a bacterium antagonistic to a Fusarium strain was isolated from the compost. The isolate (Bacillus sp. NP-1) produced an antifungal compound, iturin A. These results suggest that this compost serves as a valuable source of plant growth-promoting rhizobacteria including the antifungal bacteria.

Removal of o-xylene using biofilter inoculated with Rhodococcus sp. BTO62.

Rhodococcus sp. BTO62 was isolated from activated sludge from a wastewater treatment plant as an o-xylene-degrading microorganism. BOT62 degraded not only o-xylene, but also benzene, toluene, ethylbenzene, m- and p-xylenes and styrene (BTEXS). A laboratory scale biofilter packed with Biosol as packing material, which is made from foamed waste glass mixed with corrugated cardboard, was inoculated with strain BTO62 and operated to remove relatively high loading of o-xylene at different space velocities under non-sterile and sterile conditions. The o-xylene elimination capacity to maintain more than 90% removal efficiency was 41g/m3/h under sterile condition, but it enhanced to 160g/m3/h under non-sterile condition. This indicates possibilities of the role of other contaminants for degradation of o-xylene and the degradation of intermediate products of o-xylene by contaminants. Quick recovery of o-xylene degradation was observed after shutdown of o-xylene gas supply and mineral medium circulation for 10-30 days.

Improvement in ammonium removal efficiency in wastewater treatment by mixed culture of Alcaligenes faecalis no. 4 and L1.

To improve ammonium removal efficiency in wastewater treatment, a mixed culture of Alcaligenes faecalis no. 4 and its mutant L1, both of which have heterotrophic nitrification and aerobic denitrification abilities, was performed. In a batch culture, no. 4 has a higher denitrification ability than L1, but its ammonium removal rate was lower. In a mixed continuous culture in the ammonium loading range of 750 to 3500 mg-N/l/d, the average ammonium removal rate and the average denitrification ratio were 61 mg-N/l/h and 31%, respectively. In the mixed culture, the ammonium removal rate was twofold higher than that in a single culture of no. 4, the rate was similar to that in a single culture of L1, and the denitrification ratio was very high compared with that in the single culture of L1.

Removal of p-xylene with Pseudomonas sp. NBM21 in biofilter.

As a p-xylene (p-Xyl)-degrading microorganism, Pseudomonas sp. NBM21 was isolated from an activated sludge of a wastewater treatment plant. NBM21 degraded p-Xyl, m-xylene, benzene and toluene, but not o-xylene, ethylbenzene (Eb) and styrene. NBM21 was inoculated to a biofilter with Biosol as a packing material and p-Xyl removal was operated for 105 d under sterile and nonsterile conditions. The maximum elimination capacities for p-Xyl at higher than 90% removal efficiency were 160 g/m3/h and 150 g/m3/h under nonsterile and sterile conditions, respectively. A high load of Eb adversely affected to the removal of xylene.

Enhancement of styrene removal efficiency in biofilter by mixed cultures of Pseudomonas sp. SR-5.

The styrene-degrading bacterium Pseudomonas sp. SR-5 exhibited a high styrene removability in a biofilter. However, the styrene removal efficiency (RE) of SR-5 decreased with time. We carried out styrene gas removal in a biofilter inoculated with mixed cultures of SR-5 and other microorganisms to determine the possibility of obtaining an enhanced RE for a long period. The following three inocula were carried out: (i) styrene-degrading bacteria, strains 1 and 3, (ii) a benzoic acid-degrading bacterium Raoultella sp. A, and (iii) wastewater from a chemical company dealing with styrene. These biofilters with mixed SR-5 showed an enhanced RE compared with those with a single culture of SR-5. The complete styrene elimination capacities for ensuring 100% styrene removal in those mixed cultures were 151, 108 and 124 g/m(3)/h, compared with a single culture of SR-5.

Piggery wastewater treatment using Alcaligenes faecalis strain No. 4 with heterotrophic nitrification and aerobic denitrification.

Alcaligenes faecalis strain No. 4, which has heterotrophic nitrification and aerobic denitrification abilities, was used to treat actual piggery wastewater containing high-strength ammonium under aerobic conditions. In a continuous experiment using a solids-free wastewater (SFW) mixed with feces, almost all of the 2000 NH4+ -N mg/L and 12,000 COD mg/L in the wastewater was removed and the ammonium removal rate was approximately 30 mg-N/L/h, which was 5-10 times higher than the rates achieved by other bacteria with the same abilities. The denitrification ratio was more than 65% of removed NH4+ -N, indicating that strain No. 4 exhibited its heterotrophic nitrification and aerobic denitrification abilities in the piggery wastewater.

Effect of shutdown on styrene removal in a biofilter inoculated with Pseudomonas sp. SR-5.

Styrene gas removal was carried out in a biofilter inoculated with a styrene-degrading Pseudomonas sp. SR-5 using a mixed packing material of peat and ceramic under the non-sterile condition. More than 86% removal efficiency was obtained at styrene load of 5-93 g m(-3) h(-1) for 62 days operation period and 78% carbon of removed styrene was converted to CO2. Thereafter, three kinds of styrene shutdown experiments were conducted: (i) air and mineral medium were supplied for 4 days, (ii) complete shutdown, namely no styrene, air and moisture supply was conducted for 3 days, and (iii) only air was supplied for 11 days. When styrene gas was re-supplied after (i) and (iii) shutdown experiments, styrene removal efficiency rapidly recovered, but after (ii) shutdown, recovery of styrene removal was significantly delayed. Supply of air during shutdown period was found to be enough to resume microbial activity to degrade styrene.

Characteristics of ammonium removal by heterotrophic nitrification-aerobic denitrification by Alcaligenes faecalis No. 4.

Alcaligenes faecalis no. 4 has heterotrophic nitrification and aerobic denitrification abilities. By taking the nitrogen balance under different culture conditions, 40-50% of removed NH4+-N was denitrified and about one-half of removed NH4+-N was converted to intracellular nitrogen. The maximum ammonium removal rate of no. 4 (28.9 mg-N/l/h) and its denitrification rate at high-strength NH4+-N of about 1200 ppm in aerated batch experiments at a C/N ratio of 10 were 5-40 times higher than those of other bacteria with the same ability. Only a few percent of the removed ammonium was converted to nitrite, and the main denitrification process was speculated to be via hydroxylamine which was produced by ammonium oxidation.

Performance of a styrene-degrading biofilter inoculated with Pseudomonas sp. SR-5.

Styrene removal was studied for 3 months in a laboratory-scale biofilter packed with a mixed packing material of peat and ceramic at a ratio of 1 to 1 on a dry-weight basis and inoculated with Pseudomonas sp. SR-5. More than 90% removal efficiency (RE) was attained at 1-140 g/m3/h styrene loads under nitrogen-source limitation. When RE decreased to 70% after 30 d with an increase in styrene load, readdition of SR-5 and washing of the filter packing material restored the RE to more than 90% by maintaining the population of SR-5 at 1-10% of the total cell number. The maximum elimination capacity (EC) by kinetic analysis was estimated to be 290 g/m3/h. High conversion of the removed styrene carbon to CO2, and significantly small production of cell mass from the removed carbon were confirmed.

Nitrification and denitrification in high-strength ammonium by Alcaligenes faecalis.

Alcaligenes faecalis sp. No. 4, that has the ability of heterotrophic nitrification and aerobic denitrification in high-strength ammonium at about 1200 mg-N/l, converted about one-half of removed NH4+-N to intracellular nitrogen and nitrified only 3% of the removed NH4+. From the nitrogen balance, 40-50% of removed NH4+-N was estimated to be denitrified. Production of N2 was confirmed by GC-MS and 90% of denitrified products was N2. The maximum ammonium removal rate, 29 mg-N/l h and its denitrification rate in aerated batch experiments, were 5-40 times higher than those of other bacteria with the same ability.