Xenobiotic biotransformation potential of Pseudomonas rhodesiae KCM-R5 and Bacillus subtilis KCM-RG5, tolerant to heavy metals and phenol derivatives

Two environmental bacterial isolates KCM-R5 and KCM-RG5 were selected from xenobiotic-polluted environment. KCM-R5 was identified as Pseudomonas rhodesiae and KCM-RG5 as Bacillus subtilis. KCM-R5 demonstrated tolerance to heavy metals and KCM-RG5 to heavy metals and phenol derivatives. Both strains were studied for xenobiotic biotransformation in order to contribute towards bioremediation of polluted environments. Pseudomonas rhodesiae KCM-R5 and Bacillus subtilis. KCM-RG5 possess unusual ability to utilize ortho-nitrophenol (o-NP) and 2,4- dichlorophenoxyacetic acid (2,4-D). o-NP and 2,4-D were added at concentration 30 mg/l. The possible indictive/inhibiting effect of Pb cations (40mg/l) was also studied. Pseudomonas rhodesiae KCM-R5 removed 86 % of o-NP and below 1% of 2,4-D. Bacillus subtilis KCM-RG5 eliminated 83% of o-NP andunder 1% of 2,4-D. Biotransformation effectiveness of o-NP reached 95-100% in contrast to 2,4-D where the effectiveness was just 15-20%. Cell morphological changes were registered during the biotransformation processes. The obtained results could contribute to manage bioremediation processes in polluted with heavy metals and phenol derivatives environments. . 1, . 2, . 2, .

Phenol Biodegradation by Two Xenobiotics-Tolerant Bacteria Immobilized in Polyethylene Oxide Cryogels

Biofilms were formed on poly(ethylene oxide) (PEO) cryogels by using bacteria cultured from xenobiotics polluted environments and their phenol biodegrading capability was studied. PEO cryogels were synthesized via UV irradiation cross linking of moderately frozen aqueous system. Two xenobiotics tolerant bacterial isolates KCM R5 and KCM RG5 were used to construct the biofilms on the cryogels. Obtained PEO-biofilms were assessed for their ability to remove phenol at concentrations 300, 400, 600 and 1000 mg L-1 for 28 days. The biofilm PEO-KCM RG5 removed phenol up to 600mg L-1/24 h, whereas the biofilm PEO-KCM R5 was able to degrade up to 1000 mg L-1/24 h. The high content of free-water in the cryogels allowed reproduction of the used bacteria. The high content of free-water in the cryogels allowed reproduction of the used bacteria. Short initial adaptation of the PEO-bio�lms with 100 mg L-1/24 h phenol was crucial for protecting the bacterial cells from dead. The obtained results showed that the liquid debit through the bio�lms on the 28th day of the experiments was lower than at the beginning. The cryogels demonstrated non-toxicity, high biocompatibility with bacteria and excellent mechanical characteristics. After aggressive phenol treatment the PEO-biofilms remained compact, porous and elastic. The investigated new biological materials demonstrate potential for application in the industrial wastewater treatment technologies

COLD ARGON PLASMA TORCH FOR WATER TREATMENT

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Biological control and management of the detoxication wastewater treatment technologies

Detoxication technologies require the combination of theoretical and practical knowledge of xenobiotic biodegradation, wastewater treatment technologies, and management rules. The purpose of this complicated combination is to propose specialized strategies for detoxication, based on lab- and pilot-scale modeling. These strategies include preliminary created algorithms for preventing the risk of water pollution and sediments. The technologies and algorithms are essentially important outcome, applied in the textile, pharmaceutical, cosmetic, woodtreating, and oiltreating industries. In this paper four rehabilitation technologies for pretreatment of water contaminated by pentachlorophenol (PCP) have been developed in the frame of the European and Bulgarian National projects. Emphasize is put on the biological systems and their potential of detoxication management. The light and transmission electron microscopy of the reconstructed activated sludges the microbial, kinetic and enzymological indicators are presented and approved as critical points in the biocontrol

Investigating the Functional and Structural Adaptation Changes of Biofilm Communities Toward Better Azo-dye Wastewater Treatment

Aims: The aim of this study was to investigate the functional and structural adaptation changes in three biofilm communities purifying azo-dye contaminated wastewater. Study Design: Three lab-scale sand biofilters were constructed for treating wastewater with azo-dye. The dye amaranth was chosen as model toxicant and its concentration was gradually increased in the wastewater from 10 mg/L up to 55 mg/L. The biofilters functioned for 26 days. Place and Duration of Study: Laboratory of Environmental biotechnology, Sofia University “St. Kliment Ohridski”, 2011-2013 year. Methodology: The residual amaranth concentration, efficiency and rate of its removal were monitored. The diagnostics of the functional structure of the biofilms is based on a cross analysis of data from culturable, culture-independent (fluorescent in-situ hybridization - FISH) and digital (digital image processing) techniques. Results: The efficiency of the biofilters varied from 88.35% up to 95.97%. Three phases of the azo-detoxification process were distinguished. In the early phase of functioning (0-191 h) culturable Pseudomonas sp. had key role in azo-degradation as their part of the community was about 70% for the three biofilters. In the late phase of functioning (191-455 h) the biofilters eliminated 2 times higher concentration of amaranth. The mean value for the part of the microorganisms from g. Pseudomonas, calculated on the base of FISH, remained unchanged (42%). Simultaneously the cultivation techniques showed significantly decreased part of Pseudomonas sp. (4-10%). This suggest an important role of the unculturable Pseudomonas sp. In the ending period (455-623 h) the rate of amaranth removal was increased with 20%. Well-formed zones with high concentration of bacteria from g. Pseudomonas were found in the biofilms which indicated formation of cooperative relationships. Conclusion: This study shows three-stage mechanism of development of amaranth degradation potential. It includes successive importance of culurable, unculturable bacteria and cooperation in the g. Pseudomonas

MICROBIAL CULTURE ADAPTATION TO BIODEGRADATION OF DIMETHYLTEREPHTHALATE

Forty-five microbial cultures have been isolated from a chemically polluted region, using dimethylterephthalate (DMT) as a sole carbon and energy source. They have been subjected to adaptive selection in order to increase their biodegradative potential. The gradual increase of the xenobiotic substrate concentration from 2.5 to 25 mM induced adaptive changes in the tested strains. 20% of the studied strains showed a high biodegradative activity towards DMT and the best adaptation was expressed by the soil microorganisms

Application of residual sludges from wastewater treatment technologies for construction of biofertiliser

To stimulate plant development in phytoremediation or in the cultivation of non-food crops in potentially contaminated soils, a biotechnologically created product could be applied. The aim of this study was to explore the possibility of creation of biofertiliser, based on activated sludge combined with bacterial strain with detoxifying and plant growth promoting properties. The presented study is focused on the effect of phenol in the following concentrations: 5 mg/l, 100 mg/l, 250 mg/l, 500 mg/l and 1000 mg/l on the metabolic activity of Brevibacillus laterosporus BT271. The gradual increased concentration of phenol was used to study the metabolic activity of mineralised activated sludge and B. laterosporus BT271. The CTC/DAPI staining showed high activity of the bacteria even at the highest concentration. The greatest amount of biomass was accumulated at 5 mg/l phenol (4.44 × 107 cells/ml). At this toxicant concentration, a total dehydrogenase activity of 5.72 × 10-4 μg H+/ml*min was found. Studies of the metabolic activity of microorganisms in experiments involving a combination of mineralised activated sludge, B. laterosporus BT271 and phenol at three concentrations (5 mg/l, 250 mg/l and 1000 mg/l) showed the highest value for dehydrogenase activity in the variant with average phenolic concentration (up to 6.39 × 10-6 μg H+/ml*min. The results proved the detoxification potential of B. laterosporus BT271 when different concentrations of phenol were present. The combination of a mineralised activated sludge and selected highly active biodegrading B. laterosporus BT271 showed valuable properties of detoxification and metabolic activity and keep these potentials up to 1000mg/l phenol

MICROBIAL CULTURE ADAPTATION TO BIODEGRADATION OF DIMETHYLTEREPHTHALATE

Forty-five microbial cultures have been isolated from a chemically polluted region, using dimethylterephthalate (DMT) as a sole carbon and energy source. They have been subjected to adaptive selection in order to increase their biodegradative potential. The gradual increase of the xenobiotic substrate concentration from 2.5 to 25 mM induced adaptive changes in the tested strains. 20% of the studied strains showed a high biodegradative activity towards DMT and the best adaptation was expressed by the soil microorganisms

Comparison of Two Methods for SARS-CoV-2 Detection in Wastewater: A Case Study from Sofia, Bulgaria

Wastewater surveillance for monitoring the spread of SARS-CoV-2 remains important even in the current endemic stage of the COVID-19 outbreak. This approach has already demonstrated its value by providing early warnings of coronavirus spread in different communities. The aim of the present publication is to share relevant experience from the Center of Competence “Clean&Circle”, obtained in the development of an effective strategy for SARS-CoV-2 detection in the wastewater of Sofia, Bulgaria. Using four different RNA concentration/extraction methods, we revealed that the key hindering factor for successful viral detection was the presence of PCR inhibitors in the wastewater. The most efficient way to overcome their presence turned out to be the application of a specialized polymerase in the RT-PCR detection setup. Our data showed that using such an enzyme increases the detection efficiency from 1.9% to 70.5% in samples with a spiked control virus. We also evaluated the recovery rates of viral particles by using silica columns (71%), PEG precipitation (23%), ultrafiltration (15%), and MCE filtration (10%). These results support the international effort to unify and standardize the various techniques used for SARS-CoV-2 monitoring in wastewater

Nanodiamonds improve amaranth biodegradation in a lab-scale biofilter

AbstractNanodiamonds (ND) are nano-particles with a size of 4–5 nm which are intensively investigated for a number of properties that make them suitable for bio-applications. They could be chemically modified, they have a high adsorption capacity, high mechanical and chemical stability. Because ND have all these properties, they are also suitable for application in specific wastewater treatment and especially when the treated water is polluted with toxic compounds. The effect of ND applied in laboratory sand biofilter was investigated in this research. Synthetic wastewater with a model toxicant, the azo-dye amaranth, was used. The results showed that, in the presence of ND, the efficiency of amaranth removal remained high (more than 90%) in concentrations close to the critical one. The level of carbon-containing pollutants (assessed as chemical oxygen demand (COD) and total organic carbon (TOC)) decreased. The number of bacteria from the key detoxification groups increased 98 times for Pseudomonas sp. and 105 times for azo-degrading bacteria, while aerobic heterotrophs increased only 6 times after ND were applied. The abundance of Pseudomonas spp. after ND addition was confirmed with fluorescence in-situ hybridization.The activities of the key enzymes increased with 26–57%. Also, the activities of cathechol-1,2-dioxygenase and catechol-2,3-dioxygenase were found after ND addition but not before that. The obtained data showed that after ND were introduced in the wastewater treatment system, the number of biodegrading bacteria increased. They synthesized large amounts of azoreductases and oxygenases that led to the improved parameters of azo-detoxification process