• Microbiology and Biotechnology Letters
• /
• v.24 no.6
• /
• pp.733-737
• /
• 1996

The formation of microbial films(biofilm) by a non-sulfur phototrophic bacteria, Rhodopseudomonas capsulata, on inorganic media was studied. Porous ceramic beads(PCB) were superior to other immobilizing media for the biofilm formation in a packed-bed reactor. It was found that the formation of microbial films favored a lower hydraulic retention time, showing a higher ratio of cells attatched to the media to those suspended in the solution. The cell concentration in the biofilm reactor was as high as 11,400mg/l, which is 8-folds of the cell concentration in an ordinary suspended treatment. It was observed that the formation of micribial film by R. capsulata followed a general serial process of cell attachment, microcolony formation, and biofilm formation. The microbial films thus formed was very stable even for an extremely high volumetric BOD loading rate of 15gBOD/l day. The scanning electron micrographs of the microbial films showed that the cells were attached to both the surface and pores of the media.

• Journal of Microbiology and Biotechnology
• /
• v.32 no.12
• /
• pp.1561-1572
• /
• 2022

Plastic pollution has been recognized as a serious environmental problem, and microbial degradation of plastics is a potential, environmentally friendly solution to this. Here, we analyzed and compared microbial communities on waste plastic films (WPFs) buried for long periods at four landfill sites with those in nearby soils to identify microbes with the potential to degrade plastics. Fourier-transform infrared spectroscopy spectra of these WPFs showed that most were polyethylene and had signs of oxidation, such as carbon-carbon double bonds, carbon-oxygen single bonds, or hydrogen-oxygen single bonds, but the presence of carbonyl groups was rare. The species richness and diversity of the bacterial and fungal communities on the films were generally lower than those in nearby soils. Principal coordinate analysis of the bacterial and fungal communities showed that their overall structures were determined by their geographical locations; however, the microbial communities on the films were generally different from those in the soils. For the pulled data from the four landfill sites, the relative abundances of Bradyrhizobiaceae, Pseudarthrobacter, Myxococcales, Sphingomonas, and Spartobacteria were higher on films than in soils at the bacterial genus level. At the species level, operational taxonomic units classified as Bradyrhizobiaceae and Pseudarthrobacter in bacteria and Mortierella in fungi were enriched on the films. PICRUSt analysis showed that the predicted functions related to amino acid and carbohydrate metabolism and xenobiotic degradation were more abundant on films than in soils. These results suggest that specific microbial groups were enriched on the WPFs and may be involved in plastic degradation.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
• /
• v.3 no.2
• /
• pp.3-16
• /
• 1996

This study was investigated to the effect of oxygen barrier of four different packaging films of the shelf life of proessed meat product by the simulated distribution test and storage test. The microbial growth, pH, VBN content, TBA value, color change and sensory evaluation were compared during the 2-month storage period at 4, 10, $20^{\circ}C$ after finished the simulated distribution test. The oxygen transmission rates ($cc/m^2$ day) were BF001: 27,88; BF003; 12.30;NY; 77.98; EVOM; 0.41 respectively. The packaging films were not effected on the changes of pH, VBN content, TBA value and color during the storage period. The aerobic microbial growth was increased only at $20^{\circ}C$ in the order of growth rate in the following films;NY > BF001 > BF003 > EVOH. Therefore, the microbial growth was affected significantly by the properties of oxygen barrier off packaging films and it should be an indicator of establishing the shelf life processed meat product.

• Ocean and Polar Research
• /
• v.26 no.1
• /
• pp.51-58
• /
• 2004

We isolated and identified culturable Arctic bacteria that had inhabited soils around the Korean Arctic Research Station Dasan located at Ny-Alsund, Svalbard, Norway $(79^{\circ}N,\;12^{\circ}E)$. The collected soils were diluted in distilled water; the diluted soil-water was spread on 3M petri-films at Dasan Station. The petri-films were transported to the laboratory at KORDI, and cultured at $4^{\circ}C$. Colonies grown on the petri-films were subsequently cultured on nutrient agar plates at $4^{\circ}C$ every 7 days. The pure colonies were inoculated into nutrient liquid media, genomic DNA was extracted, and phylogenetic analysis was performed on the basis of 165 rDNA sequences. A total of 227 strains of bacteria were isolated. Among them, 16S rDNA sequences of 185 strains were identical with those of known strains isolated in this study, and 42 strains were finally identified. Phylogenetic analysis using 16S rDNA indicated that the 30 strains belonged to Pseudomonas, 7 strains to Arthrobacter, two strains to Flavobacterium, and the remaining to Achromobacter, Pedobacter, and Psychrobacter. Among the 42 strains, 14 bacteria produced protease: they were 6 strains of Pseudomonax, 4 strains of Arthrobater, an Achromobacter strain, 2 strains of Flavobacterium, and a Pedohacter strain. We expect these Arctic bacteria can be used for screening to develop new industrial enzymes that are active at low temperatures.

• Food Science and Preservation
• /
• v.6 no.1
• /
• pp.43-47
• /
• 1999

To develop a wrapping film, which suppresses the microbial decay through the storage and distribute of greenhouse fresh produce, the antimicrobial packaging films were made and applied to the preservation of grapes(Campbell early). For the purpose the films were made by adding 1% grapefruit seed extract(GFSE) to LDPE film(Control). Graps were separately wrapped with packaging films in the state of closely-adhered packaging as well as modified atmosphere packaging(MAP). The wrapped grapes were stored at 5$^{\circ}C$ for 65 days and then the colony count of contaminated microorganims, decay ration of grapes, the gas component within the packages and chemical qualities were investigated. The antimicrobial film packaging showed the efficient results to suppress microbial growth as compared with control. The total number of containated microorganisms were decreased gradually through all the storage period. In the closely-adhered packaging and MAP the decay ratios of grapes was 31% and 19%, indivisually. After the storage period of 65 days, the interior gas components of MAP were 4.5% of O2 and 17.6% of CO2, which were efficient for the storage of grapes. In addition, no negative effects in sweetness and acidities occurred.

• Journal of Microbiology and Biotechnology
• /
• v.17 no.8
• /
• pp.1284-1290
• /
• 2007

This study was conducted to investigate the antibacterial activity and shelf-life extension effect of iceberg lettuce packed in BN/PE film. The BN/PE film has a strong microbial suppression effect on pathogenic bacteria such as Escherichia coli, Salmonella enteritidis, and S. typhimurium. The number of psychrophiles and mesophiles during 5 days of cold storage of fresh-cut iceberg lettuce at $10^{\circ}C$ packaged in BN/PE film was strictly suppressed in comparison with other tested films (OPP, PE, and PET film). When fresh processed iceberg lettuce was processed and stored under the current conditions, the shelf-life of the product was longer than 5 days in the BN/PE film package, whereas the shelf-life when using the other films tested, PE, OPP and PET, was no longer than 3-4 days. The decay rates of the iceberg lettuce packed in the BN/PE film was maintained at $29.8{\pm}2.1%$ on the 5th day of preservation. The samples packed in BN/PE film maintained an excellent visual quality during the 3 days of storage without significant differences in comparison with the initial visual quality. No browning was observed in the samples packed in BN/PE film for up to 3 days. The texture of shredded iceberg lettuce packaged in BN/PE film remained unchanged up to 3 days, and then a moderate decrease in texture was observed after 4 days of storage. In addition, the overall acceptability of fresh-cut iceberg lettuce packaged in BN/PE film did not change for up to 3 days, whereas the samples packaged in the other films were inedible by 3 days of storage. In conclusion, the shelf-life of fresh-cut iceberg lettuce packaged in the BN/PE film was extended to more than 5 days at $10^{\circ}C$, whereas that in the other films was 2 days at $10^{\circ}C$. Therefore, the shelf-life extension effect of the fresh-cut iceberg lettuce in BN/PE film packaging was very effective compared with the other films tested.

• Food Science of Animal Resources
• /
• v.36 no.2
• /
• pp.230-236
• /
• 2016

Procyanidins, which are natural antioxidants and antimicrobials found in grapes, enhance the quality and extend the shelf life of meat. We explored the effects of edible films incorporating procyanidins on pork loin stored for various times. Procyanidins (0, 0.1, and 0.3%, w/w) were incorporated into the edible films. We assessed meat color, pH, levels of volatile basic nitrogen (VBN) and 2-thiobarbituric acid-reactive substances (TBARS), and microbial populations for 14 d. The chromaticities and pH values of pork loin wrapped in film containing procyanidins (0.1% and 0.3%) generally increased (p<0.05) with storage time. VBN and TBARS levels, and total bacterial and Escherichia coli (E. coli) counts, significantly decreased (p<0.05) in the procyanidin groups. In particular, procyanidins strongly inhibited TBARS formation. Thus, our findings suggest that edible film impregnated with procyanidins inhibits lipid oxidation and microbial growth, thereby enhancing the quality and shelf life of pork meat.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.45 no.5
• /
• pp.778-781
• /
• 2016

Sea urchin skeleton (SUS) generated from production of sea urchin eggs was used as a biodegradable film base material, and its composite film with gelatin was prepared. In addition, Robinia pseudoacacia flower extract (RFE) was incorporated into the film-forming solution to provide antioxidant and anti-microbial activities. The tensile strength (TS) of the SUS/gelatin composite films increased with increasing gelatin content, whereas elongation at break (E) decreased. Among the composite films, SUS/gelatin film at a ratio of 8:2 (w/w) exhibited the most desirable TS and E values. Furthermore, SUS composite film containing RFE showed a reduced TS and increased E compared to the control film. Based on 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) and 2,2-diphenyl-1-picrylhydrazyl radical scavenging assays and disc diffusion results against growth of Listeria monocytogenes, antioxidant and anti-microbial activities of films increased with increasing RFE concentration. Consequently, SUS composite film containing RFE showed proper physical properties as well as antioxidant and anti-microbial activities. These results indicate that SUS can be used as a film base material while the SUS composite film containing RFE can be utilized as active packaging.

• Food Science of Animal Resources
• /
• v.25 no.1
• /
• pp.60-65
• /
• 2005

Antioxidant films are one active packaging technology that can extend food shelf-life through preventing lipid oxidation, stabilizing color, maintaining sensory properties and delaying microbial growth in foods. Because raw, fresh and minimal processed foods are more perishable during storage or under display conditions than further processed foods, they rapidly lose their original quality. Foods are susceptible to physical, chemical, and biochemical hazards to which packaging films can be effective barriers. Although films incorporated natural (tocopherols, flavonoids and phenolic acids) or synthetic antioxidants (BHT, BHA, TBHQ, propyl gallate) have been extensively tested to improve quality and safety of various foods, food applications require addressing issues such as physical properties, chemical action, cost, and legal approval. Increased interest in natural antioxidants as substitutes for synthetic antioxidants has triggered research on use of the new natural antioxidants in films and coatings. Use of new components (phytochemicals) as film additives can improve food quality and human health. The biosynthesis of plant phenolics can potentially be optimized by active coatings on harvested fruits and vegetables. These coatings can trigger the plants natural proline-linked pentose phosphate pathway to increase the phenolic contents and maintain overall plant tissue quality. This alternate metabolic pathway has been proposed by Dr. K. Shetty and is supported by numerous studies. A new generation of active food films will not only preserve the food, but increase food's nutritional quality by optimizing raw food biochemical production of phytochemicals.

• Journal of Pharmaceutical Investigation
• /
• v.19 no.3
• /
• pp.145-154
• /
• 1989

Methyl methacrylate-butyl methacrylate copolymer (MMBM)-povidone (PVP) films were investigated as a potential topical drug delivery system for the controlled release of econazole nitrate as a model drug. The effect of changes in film composition, drug concentration, film thickness, pH and temperature of release medium on the in vitro release of econazole nitrate were studied. The release rate constant was found to be increased with increasing povidone content in dry films. Drug release followed zero-order kinetics in the initial stage and then release rate increased gradually with time, espicially in the films having larger proportions of PVP. The release rate was found to be dependent on drug content, film thickness, the pH and temperature of release medium. Antimicrobial test showed that microbial growth was inhibited markedly with increasing proportions of PVP in films. Also drug content and film thickness affected the antimicrobial activity.