• Asian-Australasian Journal of Animal Sciences
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• v.17 no.5
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• pp.643-647
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• 2004

An in vitro experiment was carried out to investigate effects of solid associated (SAB) and liquid associated bacteria (LAB) and the type of incubation substrate on ruminal fermentation and gas production profiles. Bacterial fraction did not influence total numbers of bacteria. Gas production degradation parameters were significantly influenced by bacterial fraction and type of substrate (p<0.05). There was significant interaction between bacterial fraction and type of substrate in gas production (p<0.01). Total VFA concentration and acetic and propionic acid ratio were also influenced by bacterial fraction and type of substrate with little differences in individual VFA concentration.

• Food Science and Biotechnology
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• v.17 no.4
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• pp.842-845
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• 2008

This study was carried out to investigate the bactericidal efficacy of concentration (0.1, 0.2, and 0.4 ppm) and exposure time (10 and 30 min) of ozone on bacterial reduction rate of Salmonella typhimurium KCTC 2541 and Staphylococcus aureus ATCC 13515 in the distilled water (DW), and DW supplemented with 0.2% soluble starch (SS), and metal ion (MC) using argentums (Ag) and copper (Cu). The significant bactericidal differences of S. aureus were showed in the treatments of DW and SS, respectively, at the concentration of ozone above 0.1 ppm for 10 min, comparing the respective initial bacterial counts. The bacterial reduction of S. aureus was more sensitive than that of S. typhimurum at the same concentration of ozone. The bacterial reduction rate of SS treatment was slightly lower than that of DW treatment at the same concentration of ozone (p<0.05), however, the bacterial reduction rate of strains improved in the MC treatment compared to the DW treatment at the same concentration of ozone.

• International Journal of Oral Biology
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• v.30 no.2
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• pp.65-69
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• 2005

Periodontitis is a multi-microbial disease and the comparison of a series of periodontopathogenic and non-periodontopathogenic bacteria in terms of microbe-host interaction may provide clues to understand the microbial etiology of the disease better. When we deal with twenty different bacterial species in a study, the first technical issue is how to measure the accurate concentration and use the same number of bacterial cells. We measured bacterial concentration by enumerating bacteria stained with SYTOX green for constant time using a flow cytometer and compared the results with those obtained by plate counting. Concentrations calculated by two different methods were very close. Therefore, flow cytometric counting allowed the rapid analysis of live/dead bacteria, offering the advantage of turbidity measurement and that of colony counting together.

• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.7
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• pp.981-985
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• 2003

The changes of component through simultaneous production of bacterial cellulose and vinegars by G. persimmonis KJ145$^{T}$ were examined. As a results, pH was decreased to 3.22 at 8 days of fermentation and total acidity showed 4.66 which was the highest at the 8 days of fermentation. Brix didn't show any changes during the fermentation period. Free sugars of fermentation broth were consist of fructose, glucose and sucrose. The fructose concentration of fermentation broth was maintained highly during fermentation period (until the final 10 days) without a remarkable decrease. The cell growth of G. persimmonis KJ145$^{T}$ was very rapidly increased from the 2 days of fermentation and increased most at the 4 days of fermentation. The productivity of bacterial cellulose was increased in proportion to the fermentation period. Malic acid, succinic acid and oxalic acid were detected as a organic acid of vinegar. The concentration of acetic acid was rapidly increased from the 2 days and reached highest concentration at 8 days. In conclusion, the results indicated that the 8 days was the optimal fermentation period to produce the bacterial cellulose and vinegar by G. persimmonis KJ145$^{T}$ simultaneously.

• Toxicological Research
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• v.12 no.1
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• pp.17-20
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• 1996

The effect of Fumonisin B1, a mycotoxin produced by Fusarium moniliforme on bacterial viruses P1 and Lambda, was investigated by the virus plaque assay. Fumonisin B1 inhibited the P1 viral multiplication in the concentration range from $100{\mu}g$/ml to $400{\mu}g$/ml. The inhibition was Fumonisin B1 concentration-dependent. Another bacterial virus Lambda multiplication was also inhibited by lower concentration of Fumonisin B1 ($10{\mu}g$/ml~$50{\mu}g$/ml). This inhibition was dependent on Fumonisin B1 and on virus-Fumonisin B1 reaction time. Sensitivity of bacteriophage Lambda to Fumonisin B1 was higher than that of P1 virus. Lambda vital DNA was treated in vitro with Fumonisin B1 at various concentration. Significant DNA fragmentation by Fumonisin 191 was observed in the agarose gel electrophoresis. Lambda viral DNA was partially digested even in the Fumonisin B1 $10{\mu}g$ and the level of its fragmentation was dependent on Fumonisin B1 amount up to $30{\mu}g$ per assay.

• Membrane and Water Treatment
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• v.10 no.1
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• pp.29-38
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• 2019

Microbial community and composition in stormwater runoff from mixed land use land cover (LULC) catchment with ongoing land development was diverse across the hydrological stage due different environmental parameters (hydrometeorological and physicochemical) and source of runoff. However, limited studies have been made for bacterial composition in this catchment. Therefore, this study aims to: (1) quantify the concentration of fecal indicator bacteria (FIB), stormwater quality and bacterial composition and structure according to hydrological stage; and (2) determine their correlation to environmental parameters. The 454 pyrosequencing was used to determine the bacterial community and composition; while Pearson's correlation was used to determine the correlation among parameters-FIB, stormwater quality, bacterial composition and structure-to environmental parameters. Results demonstrated that the initial and peak runoff has the highest concentration of FIB, stormwater quality and bacterial composition and structure. Proteobacteria, Bacteroidetes, Actinobacteria and Firmicutes were dominant bacteria identified in this catchment. Furthermore, the 20 most abundant genera were correlated with runoff duration, average rainfall intensity, runoff volume, runoff flow, temperature, pH, organic matter, nutrients, TSS and turbidity. An increase of FIB and stormwater quality concentration, diversity and richness of bacterial composition and structure in this study was possibly due to leakage from septic tanks, cesspools and latrines; feces of domestic and wild animals; and runoff from forest, destroyed septic system in land development site and urban LULC. Overall, this study will provide an evidence of hydrological stage impacts on the runoff microbiome environment and public health perspective.

• Journal of the Korean Society of Visualization
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• v.6 no.2
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• pp.45-50
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• 2008

It has been found that the colony size of bacteria grown on an agar plate decreases with increasing agar gel concentration. Evidenc from recent studies suggests that the bacterial colony dynamics is closely related with the mechanical properties of the substrate. We investigate whether bacterial growth on the agar substrate is controlled mostly by the nutrients' diffusion which is hindered more in porous medium than in solution. The number of bacterial cells in single colonies is found to be inversely correlated with agar concentration. High-resolution live cell imaging at the single bacterium level confirms that the bacterial growth rate is reduced with increasing agar concentration. There is a strong correlation between the slowed diffusion and the reduced number of cells in a high concentration of agar medium.

• International Journal of Oral Biology
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• v.40 no.4
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• pp.189-196
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• 2015

Minimal inhibitory concentration (MIC) is the lowest antibiotic concentration that inhibits the visible growth of bacteria. Sub-minimal inhibitory concentration (Sub-MIC) is defined as the concentration of an antimicrobial agent that does not have an effect on bacterial growth but can alter bacterial biochemistry, thus reducing bacterial virulence. Many studies have confirmed that sub-MICs of antibiotics can inhibit bacterial virulence factors. However, most studies were focused on Gram-negative bacteria, while few studies on the effect of sub-MICs of antibiotics on Gram-positive bacteria. In this study, we examined the influence of sub-MICs of doxycycline, tetracycline, penicillin and amoxicillin on biofilm formation and coaggregation of Streptococcus gordonii, Streptococcus mutans, Actinomyces naeslundii, and Actinomyces odontolyticus. In this study, incubation with sub-MIC of antibiotics had no effect on the biofilm formation of S. gordonii and A. naeslundii. However, S. mutans showed increased biofilm formation after incubation with sub-MIC amoxicillin and penicillin. Also, the biofilm formation of A. odontolyticus was increased after incubating with sub-MIC penicillin. Coaggregation of A. naeslundii with S. gordonii and A. odontolyticus was diminished by sub-MIC amoxicillin. These observations indicated that sub-MICs of antibiotics could affect variable virulence properties such as biofilm formation and coaggregation in Gram-positive oral bacteria.

• Mycobiology
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• v.28 no.3
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• pp.123-126
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• 2000

Sodium hypochlorite alkaline was tested against Pseudomonas tolaasii causing bacterial blotch on cultivated oyster mushroom (Pleurotus ostreatus). The minimum inhibitory concentration of sodium hypochlorite against P. tolaasii contained active chlorine (AC) at 1.4 mg/l on plate assay. The highest cultivation yield was obtained from the treatment of AC 5.7 mg/l. Treatment of sodium hypochlorite at the rate of higher than AC 11.4 mg/l resulted in reduced yields at the harvest. However, the population of total bacteria on the bed surface treated with AC 5.7 mg/l of sodium hypochlorite was maintained to some extent. Inhibitory concentration against total bacteria on the bed surface was over AC 22.8 mg/l. Mushroom mycelium was damaged and its growth strongly inhibited at the concentration of AC 200 mg/l. Mushroom caps showed yellowish symptom by chemical injury by treatments of AC 74.1 mg/l or higher. Sporocarps infected by P. tolaasii were irrevocable at any concentration of sodium hypochlorite. Routine watering with AC 5.7 mg/l from mushroom initiation to the end of picking resulted in reduced bacterial blotch incidence of 40% and 86% at two mushroom farms. The treatment resulted in higher quality mushroom production compared to that conventionally watered with tap water alone.

• Asian-Australasian Journal of Animal Sciences
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• v.4 no.4
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• pp.369-375
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• 1991

A series of in vitro incubation studies with washed rumen bacteria were conducted to determine the influence of incubation time and concentrations of peptides, alanine, ammonia nitrogen and carbohydrate on the rate of peptide disappearance and on bacterial growth. Disappearance rate of tri-alanine (ala3) under various conditions was between 30.6 and $58.2mg\;hr^-$ per gram bacterial dry matter. Ala3 was removed from the incubation medium in an almost linear fashion as incubation time and ala3 concentration was increased. Washed rumen bacteria utilized ala3 faster than di-l-alanine (ala2) at all concentrations. Adding 9mM carbohydrate significantly increased ala3 disappearance, but level of ammonia nitrogen had no influence on ala3 disappearance. The presence of alanine in the medium significantly lowered ala3 utilization by rumen bacteria. Bacterial dry matter and nitrogen growth yield were not influenced by alanine and peptides when incubation medium already contained a sufficient level of ammonia nitrogen. Increased ammonia nitrogen in the presence of ala3 did not stimulate bacterial growth. Carbohydrate significantly increased bacterial dry matter and nitrogen growth as expected. Results indicate that the rate of peptide utilization by rumen bacteria may be altered by type and concentration of peptides, and energy supply, and this may be mediated through changes in numbers and type of bacteria.