Biodegradation and Anti-Bacterial Properties of PLA and Wood/PLA Composites Incorporated with Zeomic Anti-Bacterial Agent

2013 ◽  
Vol 747 ◽  
pp. 111-114 ◽  
Author(s):  
Chana Prapruddivongs ◽  
Narongrit Sombatsompop
Keyword(s):  
Wood Flour ◽  
Viable Cell ◽  
Chain Scission ◽  
Plate Count ◽  
Poly Lactic Acid ◽  
Aerobic Degradation ◽  
Carbon Conversion ◽  
Plate Count Agar ◽  
Bacterial Agent ◽  
Biodegradation Test

Anti-bacterial and biodegradation activities of Poly (lactic acid) (PLA) and wood flour/PLA composites (WPLA) were investigated for the effect of anti-bacterial agent addition. Silver substituted Zeolite (commercially designated as Zeomic) was used as anti-bacterial agent in this study. Anti-bacterial activities were investigated through dynamic shake flask method accompanying with plate count agar (PCA) technique, against Staphylococcus aureus as testing bacteria. The results of anti-bacterial activity were reported by viable cell count. For biodegradation test, the degree and rate of biodegradations were evaluated from percentage of carbon conversion, the test being carried out under laboratory controlled-aerobic degradation environment at a temperature of 58±2°C. The results found that addition of Zeomic did not perform anti-bacterial activities for both the neat PLA and WPLA due to non-diffusivity of silver in Zeomic. For biodegradation test, both PLA and WPLA samples during incubation times of 21-60 days had shown considerable biodegradation rates as a result of chain scission by hydrolysis reaction and subsequent enzymatic-biodegradation by microorganism of PLA molecules. Regarding the effect of wood and Zeomic addition, it was found that introducing wood and Zeomic in PLA matrix tended to markedly increase the degree and rate of biodegradation of PLA and WPLA materials, whereby the PLA having 10%wt of wood with 1.5%wt of Zeomic had the most satisfactory biodegradation level and rate as a consequence of accelerated hydrolysis degradation from moisture in wood and Zeomic.

Wood, silver-substituted zeolite and triclosan as biodegradation controllers and antibacterial agents for poly(lactic acid) (PLA) and PLA composites

2015 ◽  
Vol 30 (5) ◽  
pp. 583-598 ◽  
Author(s):  
Chana Prapruddivongs ◽  
Narongrit Sombatsompop
Keyword(s):  
Lactic Acid ◽  
Antimicrobial Agents ◽  
Wood Flour ◽  
Plate Count ◽  
Poly Lactic Acid ◽  
Mechanical And Thermal Properties ◽  
Scanning Calorimetry ◽  
Elongation At Break ◽  
Plate Count Agar ◽  
Twin Screw

Poly(lactic acid) (PLA) and wood flour/PLA composites were prepared and blended with two antimicrobial agents, triclosan and silver-substituted zeolite (Zeomic), using a twin-screw extruder. The mechanical and thermal properties, antimicrobial activity, and biodegradation performance were investigated. The addition of wood and Zeomic was found to increase the Young’s modulus of the composites, whereas the tensile strength, elongation at break, and impact strength dropped. However, the mechanical properties of PLA and wood/PLA loaded with triclosan did not show any definite trends. Differential scanning calorimetry data indicated that the glass transition temperature value of neat PLA was 63°C, whereas those of wood/PLA composites were lower. When wood and Zeomic were incorporated, PLA exhibited double melting peaks. Triclosan (1.0 and 1.5 wt%) demonstrated antibacterial activity against Staphylococcus aureus, as determined by plate count agar technique, whereas Zeomic did not. Biodegradation tests of neat PLA and wood/PLA composites showed that after a 60-day incubation period, the biodegradation rate of wood/PLA was higher than that of PLA. PLA and wood/PLA-containing Zeomic were found to degrade more quickly, suggesting that wood and Zeomic acted as biodegradation promoters. On the other hand, triclosan could be considered a biodegradation retarder since no biodegradation was observed for any triclosan-loaded samples during the initial 20 days of incubation, while neat PLA and wood/PLA composites began to degrade within the first few days.

Effect of Wood Flour on Structural and Thermal Properties and Antibacterial Activity of PLA Filled with Triclosan

2011 ◽  
Vol 410 ◽  
pp. 67-70 ◽  
Author(s):  
Chana Prapruddivongs ◽  
Narongrit Sombatsompop
Keyword(s):  
Escherichia Coli ◽  
Antibacterial Activity ◽  
Thermal Properties ◽  
Wood Flour ◽  
Degree Of Crystallinity ◽  
Plate Count ◽  
Poly Lactic Acid ◽  
Plate Count Agar ◽  
Wide Range ◽  
Wood Particles

Poly (lactic acid) (PLA) were compounded with wood flour and triclosan. The wood/PLA composites were then characterized using differential scanning calorimeter (DSC) and the antibacterial activity was also assessed via plate count agar (PCA) under a wide range of contact times using Escherichia coli (E.coli) as the testing bacteria. The characterization results suggested that the addition of wood flour produced two melting peaks behaviour which resulted in an enlargement of degree of crystallinity (Xc) in the wood/PLA composites. These two metling peaks were probably related with re-crystallization of the PLA by the presence of wood. The antibacterial efficiency of triclosan/PLA was improved considerably by the presence of wood flour, suggesting that the wood particles could act as “anti-bacterial promoter” for the PLA.

scholarly journals Inducible Gene Expression by Nonculturable Bacteria in Milk after Pasteurization

2002 ◽  
Vol 68 (4) ◽  
pp. 1988-1993 ◽  
Author(s):  
Thusitha S. Gunasekera ◽  
Anders Sørensen ◽  
Paul V. Attfield ◽  
Søren J. Sørensen ◽  
Duncan A. Veal
Keyword(s):  
De Novo ◽  
Membrane Integrity ◽  
Viable Cell ◽  
Plate Count ◽  
Substantial Portion ◽  
Pasteurized Milk ◽  
Plate Count Agar ◽  
Cell Counts ◽  
Unit Reduction ◽  
Inducible Gene

ABSTRACT The viability of bacteria in milk after heat treatments was assessed by using three different viability indicators: (i) CFU on plate count agar, (ii) de novo expression of a gfp reporter gene, and (iii) membrane integrity based on propidium iodide exclusion. In commercially available pasteurized milk, direct viable counts, based on dye exclusion, were significantly (P < 0.05) higher than viable cell counts determined from CFU, suggesting that a significant subpopulation of cells in pasteurized milk are viable but nonculturable. Heating milk at 63.5°C for 30 min resulted in a >4-log-unit reduction in the number of CFU of Escherichia coli and Pseudomonas putida that were marked with lac-inducible gfp. However, the reduction in the number of gfp-expressing cells of both organisms under the same conditions was <2.5 log units. These results demonstrate that a substantial portion of cells rendered incapable of forming colonies by heat treatment are metabolically active and are able to transcribe and translate genes de novo.

Effect of wood particulate size on the mechanical properties of PLA biocomposite

2020 ◽  
Vol 49 (6) ◽  
pp. 465-472
Author(s):  
S. Raj Sachin ◽  
T. Kandasamy Kannan ◽  
Rathanasamy Rajasekar
Keyword(s):  
Mechanical Properties ◽  
Mechanical Characteristics ◽  
Wood Flour ◽  
Wood Particle ◽  
Poly Lactic Acid ◽  
Particle Sizes ◽  
Content Type ◽  
Particulate Size ◽  
Practical Implications

Purpose The purpose of this study is to carry out an investigation of the role of the wood particle size on the mechanical properties of poly lactic acid (PLA)-reinforced neem fiber biocomposite. Design/methodology/approach Composite test specimens were processed by reinforcing neem wood flour (NWF) in two different particle sizes, micro-sized NWF (MNWF) and nano-sized NWF (NNWF) separately into PLA. Composites were extruded at four different fiber loadings (10, 15, 20 and 25 Wt.%) into PLA matrix. The MNWF and NNWF had particle sizes varying from 5 to 15 µm and 10 to 15 nm, respectively. Findings Tensile strength, flexural strength and impact strength of PLA increased with fiber reinforcement for both the MNWF and NNWF cases. The NNWF-reinforced PLA composite at 20 Wt.% fiber loading proved to be the best composite that had outstanding mechanical properties in this research. Practical implications The developed composite can be used as a substitute for conventional plywood for furniture, building infrastructure and interior components for the automobile, aircraft and railway sectors. Originality/value A new biocomposite had been fabricated by using PLA and NWF and had been tested for its mechanical characteristics.

scholarly journals Silane Modified Wood Flour Blended with Poly(lactic acid) and its Effects on Composite Performance

BioResources ◽  
2015 ◽  
Vol 10 (3) ◽  
Author(s):  
Shanshan Lv ◽  
Haiyan Tan ◽  
Jiyou Gu ◽  
Yanhua Zhang
Keyword(s):  
Lactic Acid ◽  
Wood Flour ◽  
Poly Lactic Acid ◽  
Modified Wood

Comparison of the Petrifilm™ Yeast and Mold Culture Film Method to Conventional Methods for Enumerating Yeasts and Molds in Foods

1991 ◽  
Vol 54 (6) ◽  
pp. 443-447 ◽  
Author(s):  
L. R. BEUCHAT ◽  
B. V. NAIL ◽  
R.E. BRACKETT ◽  
T. L. FOX
Keyword(s):  
Correlation Coefficients ◽  
Food Group ◽  
Black Pepper ◽  
Plate Count ◽  
Food Groups ◽  
Plate Count Agar ◽  
Plate Counts ◽  
Yeasts And Molds ◽  
Potential Food ◽  
Film Method

Petrifilm™ Yeast and Mold (YM) plates were compared to acidified potato dextrose agar (APDA) and chloramphenicol-supplemented plate count agar (CPCA) for its suitability to enumerate yeasts and molds in 13 groups of food products. These products consisted of beans (dry and frozen, green), corn meal, flour (wheat), fruit (apple), a meat/vegetable entree (chicken pot pie), a precooked meat (beef), milk (dehydrated, nonfat), nuts (pecans), pasta, potatoes (dehydrated), precooked sausage, and a spice (black pepper). Correlation coefficients of Petrifilm™ YM plates versus APDA and CPCA pour plates for recovering total yeasts and molds from a composite of the thirteen test foods were, respectively, 0.961 and 0.974. Individually, Petrifilm™ YM plate counts were equivalent or higher than APDA and CPCA for some food groups and lower for other food groups. Because food particle interference can make enumeration of yeast and mold colonies on Petrifilm™ YM plates difficult for some food groups, potential food interference will need to be evaluated for each food group tested.

scholarly journals Cemaran bakteri pada makanan pempek produksi rumah tangga dan pabrik pengolah makanan

2020 ◽  
Vol 12 (2) ◽  
pp. 193-200
Author(s):  
Joko Sapto Pramono ◽  
Mustaming Mustaming ◽  
Dewi Samara Putri
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Random Sampling ◽  
Plate Count ◽  
Plate Count Agar ◽  
Colony Counter

Pempek merupakan makanan tradisional yang berasal dari Palembang. Makanan ini diproduksi oleh industri rumah tangga maupun pabrik pengolah makanan. Olahan ikan ini beresiko dicemari oleh bakteri Escherichia coli, Salmonella, dan Staphylococcus aureus. Penelitian ini bertujuan untuk mengetahui cemaran bakteri pada pempek yang dijual di pasaran kota Samarinda. Jenis penelitian yang digunakan adalah penelitian laboratorium. Teknik sampling yang digunakan yaitu random sampling. Jumlah sampel yang diperoleh sebanyak 20 sampel pempek, 10 sampel produksi industri rumah tangga dan 10 sampel produksi pabrik. Sampel kemudian dibawa ke laboratorium dan dilakukan pemeriksaan jumlah koloni dengan menggunakan colony counter. Hasil penghitungan Angka Lempeng Total (ALT) pada media Plate Count Agar (PCA) menunjukkan bahwa sebanyak 18 sampel (90%) yang terdiri dari 10 sampel pempek produksi pabrik dan 8 sampel pempek produksi rumahan mengandung cemaran mikroba yang tinggi (> 5x 104). Masyarakat disarankan memasak pempek hingga matang sebelum mengkonsumsi baik pempek produksi pabrik maupun produksi rumahan agar terhindar dari resiko cemaran bakteri patogen. Catatan PenerbitPoltekkes Kemenkes Kendari menyatakan tetap netral sehubungan dengan klaim dari perspektif atau buah pikiran yang diterbitkan dan dari afiliasi institusional manapun. PendanaanKajian terlaksana atas pembiayaan sukarela peneliti. Konflik KepentinganPara penulis menyatakan bebas dari konflik kepentingan. Berbagi DataData hasil kajian tersedia melalui permohonan kepada penulis koresponden. Kontribusi PenulisPara penulis tidak mendeklarasikan setiap kontribusinya.

scholarly journals Improving and Comparing Probiotic Plate Count Methods by Analytical Procedure Lifecycle Management

2021 ◽  
Vol 12 ◽  
Author(s):  
M. L. Jane Weitzel ◽  
Christina S. Vegge ◽  
Marco Pane ◽  
Virginia S. Goldman ◽  
Binu Koshy ◽  
...  
Keyword(s):  
Analytical Procedure ◽  
Health Benefit ◽  
Viable Cell ◽  
Plate Count ◽  
Data Set ◽  
Colony Forming Units ◽  
Specific Factors ◽  
And Control ◽  
Lifecycle Management ◽  
Development Laboratory

Probiotics are live microorganisms that confer a health benefit to the host when administered in adequate amounts. This definition links probiotic efficacy to microbial viability. The current gold standard assay for probiotic potency is enumeration using classical microbiology plating-based procedures, yielding results in colony-forming units (CFU). One drawback to plating-based procedures is high variability due to intrinsic and extrinsic uncertainties. These uncertainties make comparison between analytical procedures challenging. In this article, we provide tools to reduce measurement uncertainty and strengthen the reliability of probiotic enumerations by using analytical procedure lifecycle management (APLM). APLM is a tool that uses a step-by-step process to define procedure performance based on the concept that the reportable value (final CFU result) must be fit for its intended use. Once the procedure performance is defined, the information gathered through APLM can be used to evaluate and compare procedures. Here, we discuss the theory behind applying APLM and give practical information about its application to CFU enumeration procedures for probiotics using a simulated example and data set. Data collected in a manufacturer’s development laboratory is included to support application of the concept. Implementation of APLM can lead to reduced variability by identifying specific factors (e.g., the dilution step) with significant impact on the variability and providing insights to procedural modifications that lead to process improvement. Understanding and control of the analytical procedure is improved by using these tools. The probiotics industry can confidently apply the information and analytical results generated to make decisions about processes and formulation, including overage requirements. One benefit of this approach is that companies can reduce overage costs. More reliable procedures for viable cell count determinations will improve the quality evaluation of probiotic products, and hence manufacturing procedures, while ensuring that products deliver clinically demonstrated beneficial doses.

scholarly journals Styrene-Assisted Maleic Anhydride Grafted Poly(lactic acid) as an Effective Compatibilizer for Wood Flour/Poly(lactic acid) Bio-Composites

Polymers ◽  
2017 ◽  
Vol 9 (11) ◽  
pp. 623 ◽  
Author(s):  
Jun Du ◽  
Youyong Wang ◽  
Xinfeng Xie ◽  
Min Xu ◽  
Yongming Song
Keyword(s):  
Lactic Acid ◽  
Maleic Anhydride ◽  
Wood Flour ◽  
Poly Lactic Acid

Potato-Like Odor of Retail Beef Cuts Associated with Species of Pseudomonas

1986 ◽  
Vol 49 (4) ◽  
pp. 272-273 ◽  
Author(s):  
R. L. DAISE ◽  
E. A. ZOTTOLA ◽  
R. J. EPLEY
Keyword(s):  
Coliform Bacteria ◽  
Plate Count ◽  
Aerobic Bacteria ◽  
Gram Negative ◽  
Consumer Complaints ◽  
Psychrotrophic Bacteria ◽  
Plate Count Agar ◽  
Litmus Milk ◽  
Musty Odor ◽  
Retail Cuts

Retail cuts of beef and hamburger packages from a North Dakota meat processor were examined due to consumer complaints of a strong potato-like or musty odor associated with the meat. Examination for total numbers of aerobic bacteria on plate count agar and for gram-negative psychrotrophic bacteria on crystal violet tetrazolium agar revealed numbers in excess of 108 CFU/g. Numbers of coliform bacteria on violet red bile agar were in excess of 106 CFU/g. Gram-negative rods were isolated and identified. The isolates were characterized by a positive catalase reaction, oxidase production, an oxidative O/F reaction, nonutilization of lactose, liquefication of nutrient gelatin, slight motility, production of acid in litmus milk with decoloration and clotting, nonproduction of indole, and nonreduction of nitrate. The isolate was tentatively identified as a Pseudomonas of undetermined species, probably a variant of either Pseudomonas taetrolens or Pseudomonas perolens.

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