Active Extracellular Substances Research Articles

The role of hydrocarbon-oxidizing bacteria Acinetobacter pitti. RKB1 and Bacillus sp. RKB2 in the processes of bio-solubilization of brown coal from the Kiyakty coal deposit (Karaganda, Kazakhstan)

According to the obtained results, it was established that two strains from five hydrocarbon-destroying bacteria tested on coal – Acinetobacter pitti. RKB1 and Bacillus sp. RKB2 that can solubilize purebrown and pre-treated with nitric acid coal. It was established that 25-28% of raw coal was dissolved indry weight within 30 days. Pretreatment of coal with nitric acid increased the efficiency of this processby 52% when Bacillus sp. RKB2 used. The extracellular solubility of coal with the usage of microbialstrains decreased pH slightly, which indicates the contribution of some alkaline substances to the dissolution of lignite. However, the biosolubilization mechanisms of lignite of two strains were different.These can be either active extracellular substances that synthesized with Acinetobacter pitti. RKB1 or itcan be some enzymes yielded with Bacillus sp. RKB2. Elemental analysis of coals that pretreated withHNO3 and biosolubilization products formed under the action of Acinetobacter pitti. RKB1, or Bacillussp. RKB2 showed significant differences between lignite and products that formed during the microbialconversion of coal.Key words: Lignite, leonardite, biosolubilization.

EFFECT OF ANTIMICROBIAL AGENTS ON THE BIOFILM GROWTH OF CLINICAL ISOLATES

OBJECTIVE. To study the effect of active extracellular substances of lactobacilli and antimicrobial agents on the inhibition and destruction of the biofilms formed clinically relevant microorganism strains. MATERIALS AND METHODS. The study of the impact of different agents on the biofilmformation and growth was carried out on resistant clinical strains of microorganisms obtainedfrom patients with post-surgical infectious inflammatory complications. We used wound dressing solution, cutaneous antiseptic, filtrates of 19 clinical strains of lactobacilli and a strain of Lactobacillus plantarum from the probiotic «Lactobacterin dry» (Microgen Nizhny Novgorod, series 46 / 06-1209) as a reference strain-producer of bacteriocins for biofilm inhibition. Biofilms were incubated for 48 hours on glass carriers at 37°C and visualized with a light microscope at 960x magnifying. RESULTS. All substances possess a good inhibitory potential and have approximately same level of effect. The skin antiseptic and wound washing fluid have only an inhibiting effect on the biofilmformation process, while the having a bactericidal effect on plantonicform of the cells. The lactobacilli filtrate inhibited the biofilmformation and was also able to destroy preformed 24-hour bacterial films. CONCLUSION. The use of lactobacilli bacteriocins can reveal additional opportunities for combating the infection associated with biofilm forming microorganisms.

Cell disruption of Chlorella vulgaris using active extracellular substances from Bacillus thuringiensis ITRI-G1 is a programmed cell death event

Microalgae are rich resources for high-value nutrients and biodiesel production. However, extraction of these valuable compounds from them requires costly energy-consuming procedures due to their rigid cell walls. Application of cell-disruptive agents, the AES-Bt agents, extracted from an algicidal bacterium, Bacillus thuringiensis ITRI-G1, are a promising way to reduce the cost of cell disruption. Treatment with AES-Bt agents resulted in a rapid decline of photosynthesis ability and caused cell death in Chlorella vulgaris. Hallmarks of programmed cell death (PCD), including chromatin condensation, DNA fragmentation, and phosphatidylserine externalization, were detected in C. vulgaris cells treated with the AES-Bt agents. Therefore, the cell disruption effect caused by application of the AES-Bt agents can be due to the occurrence of PCD. Similar to other PCDs, the PCD caused by AES-Bt agents was also associated with increased reactive oxygen species (ROS). However, co-treatments with diphenyleneiodonium chloride (DPI), an NAD(P)H oxidase inhibitor, or N,N′-dimethylthiourea (DMTU), a hydrogen peroxide (H2O2) trap, with the AES-Bt agents successfully reduced ROS production, and more cells displayed a feature of PCD detected after the co-treatments. In conclusion, the AES-Bt agents can promote PCD of microalgae; however, the mechanism may not be through induction of ROS.

Active extracellular substances of Bacillus thuringiensis ITRI-G1 induce microalgae self-disruption for microalgal biofuel.

Microalgal cultures are a clean and sustainable means to use solar energy for CO2 fixation and fuel production. Microalgae grow efficiently and are rich in oil, but recovering that oil is typically expensive and consumes much energy. Therefore, effective and low-cost techniques for microalgal disruption and oil or lipid extraction are required by the algal biofuel industry. This study introduces a novel technique that uses active extracellular substances to induce microalgal cell disruption. A bacterium indigenous to Taiwan, Bacillus thuringiensis, was used to produce the active extracellular substances, which were volatile compounds with high thermal stability. Approximately 74% of fresh microalgal cells were disrupted after a 12-h treatment with the active extracellular substances. Algal lipid extraction efficiency was improved and the oil extraction time was decreased by approximately 37.5% compared with the control treatment. The substances effectively disrupted fresh microalgal cells but not dehydrated microalgal cells. An analysis of microalgal DNA from fresh cells after disruption treatment demonstrated typical DNA laddering, indicating that disruption may have resulted from programmed cell death. This study revealed that biological treatments are environmentally friendly methods for increasing microalgal lipid extraction efficiency, and introduced a microalgal cell self-disruption mechanism.

Enhancing the oil extraction efficiency of Chlorella vulgaris with cell-disruptive pretreatment using active extracellular substances from Bacillus thuringiensis ITRI-G1

An isolated bacterium, identified as Bacillus thuringiensis ITRI-G1, was able to produce active extracellular substances (denoted as AES-Bt) that exhibited efficient cell disruptive ability for a lipid-rich microalga Chlorella vulgaris CNW-11. Pretreatment of the microalga with AES-Bt for 24h led to an increase in the extracted oil content from 34.2% to 44.3% (dry weight basis), representing an enhanced oil extraction efficiency (ηoil) of 29.3%. The ηoil value remained within the range of 26.3–33.2% when increasing the algae biomass loading from 5.0g/l to 40.0g/l (or decreasing AES-to-algae ratio from 200 to 25ml/g), while the maximum ηoil value was obtained when an AES-to-algae ratio of 50ml/g was used. Finally, reuse of AES-Bt agent was also examined. The results show that the enhanced lipid extraction efficiency slightly decreased as the number of recycling times increased. However, after being recycled and reused for four times, the AES-Bt agents could still effectively disrupt the cell wall, leading to around 92% of the original oil extraction efficiency that was obtained when the AES-Bt agents were first used. This study demonstrates that biological cell-disruptive pretreatment using the AES-Bt agents could be an effective and environmentally friendly means of increasing oil extraction efficiency with microalgae.

Biosolubilization of Polish brown coal by Gordonia alkanivorans S7 and Bacillus mycoides NS1020

Two of five tested crude oil hydrocarbon-degrading bacteria, Gordonia alkanivorans S7 and Bacillus mycoides NS1020, solubilized crude and nitric acid-pretreated brown coal. Around 30–36% crude coal dry weight was solubilized within 14days. The nitric acid pretreatment of the coal increased process efficiency by around 89% for G. alkanivorans S7. The extracellular coal-solubilizing activities of both the strains decreased with a decrease in pH, suggesting the contribution of some alkaline substances to lignite solubilization. Furthermore, this process was considerably intensified by ammonium oxalate. Mechanisms of lignite biosolubilization by the two strains were different because the active extracellular substances synthesized by B. mycoides NS1020 were thermostable while in the case of G. alkanivorans S7 some enzymes might be involved. Elemental analysis and FTIR spectra of 8N HNO3 pretreated coal and biosolubilization products generated by G. alkanivorans S7 and B. mycoides NS1020 showed significant differences between the lignite and these products. This is the first report presenting brown coal biosolubilization by crude oil hydrocarbon-degrading bacteria.

MORPHOGENESIS OF MONOSTROMA OXYSPERMUM (KÜTZ.) DOTY (CHLOROPHYCEAE) IN AXENIC CULTURE, ESPECIALLY IN BIALGAL CULTURE1

ABSTRACTThe typical morphology of Monostroma oxyspermum (Kütz.) Doty is lost in axenic culture. In synthetic media of the ASP type, it grows as a colony‐like mass composed of round cells with numerous rhizoids. Such a mass is a fragile structure which falls apart upon shaking, or slight touch, into small cell‐groups and single cells or cells with a long rhizoid. Only temporary saccate or monostromatic fronds appear and reach 1–2 mm in length when grown in enriched seawater media, but disintegrate and become a colony‐like mass. The typical morphology is easily restored by adding at specific intervals filtrates of bacterial cultures and supernatant medium from axenic brown and red algal cultures to the basal medium (ASP7), or by reinfecting the Monostroma with an appropriate bacterial flora. Furthermore, the typical morphology in also maintained by bialgal cultures between Monostroma and other axenic strains of various species of seaweeds except the species belonging to the Chlorophyceae. Monostroma thus appears to utilize some substances released by most species of brown and red algae for its typical growth. Active substances released by bacteria, brown and red algae have not yet been identified and purified. However, it is demonstrated that in axenic cultures many species of seaweeds produce active extracellular substances which play an important role in growth and Morphogenesis of other species of seaweeds.

Behaviors of a vigorous protease-producing strain of Staphylocollus aureus in the skin tissue of mice.

The behaviors of a protease-producing strain of Staphylococcus aureus, including the production of alpha- and beta-hemolysin, protease, and nuclease in the skin tissue of mice, were examined by the fluorescent antibody technique and hematoxylin and eosin staining. When about 10(6) viable cells were subcutaneously inoculated into a mouse, they were phagocytized by leukocytes and a suppurative focus developed in situ. No active extracellular substances other than alpha-hemolysin were demonstrated in this mouse. When 10(7) viable cells were inoculated, most of them were also phagocytized by leukocytes, and a rather large suppurative focus was formed. In this focus a low degree of multiplication of the organisms was observed. Protease and alpha-hemolysin could be detected in the neighborhood of the leukocytes. When 10(8) to 10(9) cells were inoculated, they multiplied transitorily in the subcutaneous tissue and produced the four substances mentioned above. The multiplication of bacterial cells as well as the production of extracellular substances ceased within a comparatively short period and the transitory state was similar to that in a batch fermenter. Necrotic and histolytic lesions were observed only in the mice inoculated with 10(8) to 10(9) viable cells. Similar dermatolytic lesions were also found in mice injected with 0.5 to 1.0 mg of pure protease.