This paper presents the results of research on the number of chitinolytic bacteria and chitinolytic activity of strains in the oligomesotrophic and the eutrophic lakes. Two lakes of soft and hard water and of different trophic status (in terms of nutrients contents) from Iławskie Lake District (North Poland) were choosen. The numbers of chitinolytic bacteria were higher in eutrophic lake (average 1.0 × 10³ cells cm⁻³) than in oligo-mesotrophic lake (average 0.5 × 10³ cells cm⁻³) as well as in littoral versus pelagic zone. However, a higher percentage of chitinolytic bacteria (average 13%) among the total numbers of heterotrophic bacteria was found in oligo-mesotrophic lake as well as higher rate of the chitinolytic activity of bacteria (7.0 versus 4.5 nmol GlcNAc mg⁻¹ protein h⁻¹ after 6 days of incubation). The possible shortage of dissolved organic compounds in mesotrophic lake was pointed up as the reason for using the dissolved chitin as the source of carbon and nitrogen. Enterobacter aerogenes (28%), Aeromonas sp. (25%) and Chromobacterium sp. (16%) dominated in oligo – mesotrophic lake. In eutrophic lake, the most numerous species were Aeromonas hydrophila (46%) and Aeromonas sp. (15%).
The efficiency of reactive dyes adsorption onto chitin under dynamic conditions was determined. The research was carried out in an air-lift reactor. A reactive dye with chlorotriazine moiety - Black DN was reactor. A reactive dye with chlorotriazine moiety - Black DN was used. The effect of inlet Black DN concentration, chitin concentration in the reactor and flow rate on the maximum adsorption capacity of chitin under dynamic conditions, on the utilisation of the adsorption capacity of chitin and on the real working time of the reactor were investigated. The results showed that the maximum adsorption capacity of chitin was affected most by inlet dye concentration. The utilisation of the adsorption capacity of chitin, at the assumed effectiveness of dye removal, depended on inlet dye concentration and chitin concentration in the reactor. The highest efficiency was obtained at the chitin concentration in the reactor of 5 g/dm3, inlet dye concentration of 100 mg/dm3 and flow rate of 0.1 V/h.
Adsorption of reactive dyes and surfactants onto chitin from mixtures containing surfactants at constant concentration and dyes at variable concentration was investigated in the present study. Two vinylsulfonate dyes (Scarlet R, Brillantorange 3R); chlorotriazine dye (Black DN); anionic (Borutosol KRN, Siarczanol N-2) and non-ionic (Rokafenol N-8) surfactants were tested. The experiments were carried out without and with pH adjustment. The research have proved that at pH 6.2 and in surfactants presence the adsorption of vinyl-sulfonate dyes onto chitin was lower than without surfactants (control sample). It was observed that the maximum adsorption capacity of chitin in mixtures of Scarlet R and surfactants was about 3-fold lower than without surfactants and in mixtures of Brillantorange 3R and surfactants was from 2.5 to 4.1-fold lower than in control sample. At pH 3.0 the differences between maximum adsorption capacity of chitin for dyes from aqueous solutions and containing surfactants ranged from 2% (in mixture of Brillantorange 3R and Borutosol KRN) to 23% (in mixture of Scarlet R and Siarczanol N-2). The maximum adsorption capacity of chitin for Black DN (chlorotriazyne dye) in surfactants presence (from 140 to 290 mg/dm3 ) was higher at pH 6.2 as well as at pH 3.0 in comparison to control sample. Rokafenol N-8 was adsorbed the weakest onto chitin from among tested surfactants. At pH 3.0 for vinyl-sulfonate dyes the relationships between mass proportion of dye and surfactant adsorbed onto chitin (Qdye/QSAA* ) and initial concentration proportion of dye and surfactant in solution (Cdye/CSAA) was nearly linear. This indicates that dyes competed with surfactants of active sites of chitin. SAA* – Surface Active Agent (s)
This study presents results of research on occurrence of chitinolytic bacteria and fungi in water, bottom sediments, and watershed soil of an eutrophic lake and on their ability to use the crustacean skeletons (shrimp waste) as a respiration substrate. It was found that the respiration rate of bacteria and fungi during decomposition of chitin varied in different environments. The participation of chitinolytic microorganisms in water (13%) and soil (18%) was greater than in bottom sediments (5%). The respiration activity in the presence of all parts of shrimp waste and shrimp exoskeletons observed in chitinolytic bacteria was higher than that of fungi. But fungi demonstrated the highest metabolic activity in the presence of the shrimp head sections. The highest respiration activity was observed in planktonic and soil bacteria, while the lowest, in benthic strains. The chitinolytic bacteria used well all examined respiration substrates (all parts of shrimp waste – 671 mg O₂ r⁻¹ protein in 5 days, the shrimp head sections – 851 mg O₂ r⁻¹ protein in 5 days and shrimp exoskeletons – 490 mg O₂ r⁻¹ protein in 5 days). No significant differences in respiration activity were observed in chitinolytic fungi isolated from water, bottom sediments and soil. All of fungal strains demonstrated the highest metabolic activity in the presence of the shrimp head sections (average 1083 mg O₂ r⁻¹ protein in 5 days). Shrimp exoskeletons were oxidized the least efficiently (average 160 mg O₂ r⁻¹ protein in 5 days). Certain strains were not using them at all.
Изложена актуальность разработки технологии и технического обеспечения производства микобиопрепаратов на основании элиситоров полисахаридной природы – хитина и глюканов. Рассмотрены современные представления о ключевых механизмах индукции устойчивости растений. Представлена технологическая схема модельной биотехнологии получения полисахаридов из клеточной стенки гриба трутовика настоящего.
A study was carried out on the occurrence and activity of chitinolytic planktonic bacteria of Aeromonas sp., Aeromonas hydrophila and Aeromonas salmonicida species, isolated from lake Jeziorak. Among the identified strains decomposing chitin the most abundant were Aeromonas sp.. All the investigated strains showed maximum chitinolytic activity at pH 6.0. An increase in chitinolytic activity was observed that occurred along with temperature growth (10° - 40°C) and colloidal chitin concentration in the medium (0.5 - 2.5%). Their decomposing activity was most intense after a 192 h incubation time. No strain displayed activity after a 48 h incubation time.
The adsorption of reactive dye mixtures onto chitin modified with 5N KOH was investigated. Three binary mixtures were tested. Each mixture contained Blue D-5RN and either Yellow D-5GN, or Red D-8B or Black DN as the second dye. The tests were conducted without pH adjustment and after pH adjustment to 3.0. The results were based on the constants determined from double Langmuir isotherm. The maximum adsorption capacity of Blue D-5RN (control sample) in the samples without pH adjustment accounted for 97 mg/g d.w., and in the sample with pH adjustment (pH=3) – for 205 mg/g d.w. The adsorption capacity of a mixture of Red D-8B and Blue D-5RN reached 93 and 196 mg/g d.w., respectively, and in a mixture containing Yellow D-5GN – 103 and 214 mg/g d.w., respectively. The dye competition in a mixture was evaluated comparing 7 constants in Langmuir equation for mixtures and Blue D-5RN in a mixture. The adsorption capacity of Blue D-5RN in a mixture was found to be by ca. 8.8 % lower than the adsorption capacity of a dye mixture in the samples without pH adjustment and by ca. 9.4 % lower compared to the samples with adjusted pH. An explicit decline in K1 value was also observed, depending on the type of the second dye and pH. Blue D-5RN and Red D-8B characterized by a high similarity of chemical structure competed for active sites more strongly. It was confirmed by a higher (ca. 9-fold and 2.1-fold -pH=3) decrease in constants K determined for Blue D-5RN in a mixture. The experimental data showed that in the samples with pH=3, the competition for active sites between dyes was weaker.
Studies on the influence of physical and chemical factors on the activity of chitinases produced by planktonic bacteria isolated from Jeziorak Lake were carried out. The results evidenced maximum activity of bacterial strains at pH 6.0 and at 10°C and 30°C. Among the strains studied, higher activity was recorded along with an increase in colloidal chitin concentration. The highest activity was recorded at 2% concentration of chitin. The majority of strains hydrolyzed chitin most intensely after 192 h of incubation, whereas no strain revealed chitinases activity after 48 h.
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