This research was performed to investigate the dynamics of microbial community by RBC (Rotating Biological Contactor) using Rhodococcus sp. EL-GT and activated sludge. Cell counts revealed by DAPI were compared with culturable bacterial counts from nutrient agar. Colony counts on nutrient agar gave values 20∼25% and 1∼15% of cell counts (DAPI). The cell counts for the dynamics of bacterial community were determined by combination of in situ hybridization with fluorescently-labelled oligonucleotide probes and epifluorescence microscopy. Around 90∼80% of total cells visualized by DAPI were also detected by the bacteria probe EUB 338. For both reactors proteobacteria belonging to the gamma subclass were dominant in the first stage (1 and 2 stage) and proteobacteria belonging to the gamma subclass were dominant in the last stage (3 and 4 stage).

Several microorganisms which degrade phenol and trichloroethylene (TCE) were isolated from the activated sludge of a wastewater treatment plant. Among them, one isolate EL-04J showed the highest degradability and was identified as a Pseudomonas species according to morphological, cultural and biochemical properties. The phenol-induced cells of Pseudomonas EL-04J, which were preincubated in the mineral salts medium containing phenol as a sole carbon source, degraded 90% of 25μM TCE within 20 h. This strain could also utilize some of methylated phenol derivatives (o-cresol, m-cresol and p-cresol) as the sole source of carbon and energy. Cresol-induced cells of Pseudomonas EL-04J also cometabolized TCE.

Microorganisms utilizing petroleum as substrate were screened from the seawater in Pusan coastal area. Among them, fifty strains utilized bunker-A oil as a sole carbon and energy source. Five of these fifty strains were selected to experiment this study. According to the taxonomic characteristics of its morphological, cultural and biochemical properties, the selected strains were named Pseudomonas sp. EL-12, Flavobacterium sp. EL-15, Acinetobacter sp. EL-18, Enterobacter sp. EL-27 and Micrococcus sp. EL-43, respectively. The optimal medium compositions and cultural conditions for assimilation of bunker-A oil by the selected strains were 1.5-2% bunker-A oil, 0.1% NH4NO3, 1-1.5% MgSO4·7H2O, 0.05-0.15% KCl, 0.1-0.15% CaCl2·2H2O, 2.5-3.5% NaCl, initial pH 8-9, temperature 30℃ and aeration, respectively. The utilization and degradation characteristics on the various hydrocarbons by the selected strains were showed that bunker oil, n-alkane and branched alkane compounds were highly activity than cyclic alkane and aromatic hydrocarbon compounds.

Microorganisms capable of degrading trichloroethylene(TCE) using phenol as a induction substrate were isolated from industrial effluents and soil. The strain MS-64K which had the highest biodegradability was identified as the genus Micrococcus. The optimal conditions of medium for the growth and biodegradation of trichloroethylene were observed as follows; the initial pH 7.0, trichloroethylene 1,000ppm as the carbon source, 0.2% (NH_4)_2SO_4 as the nitrogen source, respectively. Lag period and degradation time on optimal medium were shorter than those on isolation medium. Growth on the optimal medium was increased. Addition of 0.1% Triton X-100 increased the growth rate of Micrococcus sp. MS-64K, but degradation was equal to optimal medium. Trichloroethylene degradation by Micrococcus sp. MS-64K was shown to fit logarithmic model when the compound was added at initial concentration of 1,000ppm.

Microorganisms producing bioemulsifier were isolated from the sea water in Pusan coastal area. The isolated strain which had the highest emulsification activity and stability was identified as the genus Acinetobacter from the results of morphological, cultural and biochemical tests and named Acinetobacter sp. EL-C6 for convenience. The compositions of optimum medium for emulsification of crude oil by Actnetobacter sp. EL-C6 were crude oil 2.0%, NH_4NO_3 0.2%, K_2HPO_4 0.01%, MgSO_4·7H_2O 1.0%, CaCl_2·2H_2O 0.1% and NaCl 3.0% at initial pH 7.5 and 30℃, respectively. The cultivation for emulsification of crude oil was carried out in 500㎖ shaking flask containing 100㎖ of the optimum medium at 30℃. The highest emulsification was observed after 5 days. The utilization on the various hydrocarbon of the Acinetobacter sp. EL-C6 showed that utilization of n-alkane compounds were better than that of aromatic compounds. Among the petroleum compounds, crude oil was best utilized by the Actnetobacter sp. EL-C6.

The biodegradable characteristics of poly-β-hydroxybutyrate(PHB) film by fungi and soil burial are investigated. As the results of the American Standards for Testing and Materials(ASTM) method, the growth of Aspergillus niger was apparent on the PHB containing plate. This suggests that PHB was utilized as the sole carbon source by Aspergillus niger and ASTM method may have applications as measuring means of biodegradability of polyhydroxyalkanoic acid(PHA). PHB film was studied by monitoring the time-dependant changes in weight loss of PHB film under 30℃ and relative humidity 80 % during pot-test. As the results of pot-test, PHB film was decomposed about 87 % in 30 days by soil microorganisms. PHB film was more slowly degraded than PHB/HV film.

The bacterial strains, which utilizes 2,4,4`-trichloro-2`-hydroxydiphenyl ether(TCHDPE) as a sole carbon source, were isolated by selective enrichment culture from soil samples of industrial waste deposits. The bacterium that showed the highest biodegradation activity was designated as EL-047R. The isolated strain EL-047R was identified as the genus Pseudomonas from the results of morphological, cultural, and biochemical tests. The optimum conditions of medium for the growth and the degradation of TCHDPE were TCHDPE 500 ppm, (NH_4)_2SO_4 0.1% as the nitrogen source, initial pH 7.0±0.1, and 37℃, respectively. In this conditions, the degradation rate of TCHDPE was about 97%. Pseudomonas sp. EL-047R was tested for resistance to several metal compounds and antibiotics. Pseudomonas sp. EL-047R was moderately grown to Cd(NO_3)_2, ZnCl_2, AgSO_4, CuSO_4 and HgCl_2. This strain was sensitive to rifampicin and kanamycin but resistant to ampicillin, penicillin, tetracyclin and chloramphenicol. Pseudomonas sp. EL-047R was grown structurally related compounds and potential metabolites of TCHDPE, and has the stability on TCHDPE biodegradation.

In order to find the most fitted biodegradation model, biodegradation kinetics model to the initial phenol and p-cresol concentrations were investigated and had been fitted by the linear regression. Bacteria capable of degrading p-cresol were isolated from soil by enrichment culture technique. Among them, strain M1 capable of degrading p-cresol has also degraded phenol and was identified as the genus Micrococcus from the results from of taxonomical studies. The optimal conditions for the biodegradation of phenol and pcresol by Micrococcus sp. M1 were NH_4NO_3 0.05%, pH 7.0, 30℃, respectively, and medium volume 100㎖/250㎖ shaking flask. Micrococcus sp. M1 was able to grow on phenol concentration up to 14mM and p-cresol concentration up to 8mM. With increasing substrate concentration, the lag period increased, but the maximum specific growth rates decreased. The yield coefficient decreased with increasing substrate concentration. The biodegradation kinetics of phenol and p-cresol were best described by Monod with growth model for every experimented concentration. In cultivation of mixed substrate, p-cresol was degraded first and phenol was second. This result implies that p-cresol and phenol was not degraded simultaneously.