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Appréciation
Concernant la présentation orale.
La durée est beaucoup trop longue (8:11 mins au lieu de 5 mins!),
Quelques erreurs à éviter comme : "the honey", "it is a medium", "ten less two, etc.." =} **ten to the power of two etc..", "Then we homogenized by keeping" =} " Then we homogenized it by keeping", "the resultat" ….. the for the calculate…."=} "the results ….. then for the calculations …", ""ten less one, etc.." =} ten to the power of one etc..", "one hundred and three point six three (113.63)"
Attention à la prononciation de certains mots comme "know", "quantities", "microorganisms", "weighed", " pipette", "petri", "sligthly", "finally", "degrees"
Il faut bien prononcer les "s" à la 3ème personne du singulier et après chaque mot au pluriel, exemple "
N'oublie pas de bien prononcer le morphème –ed : "we have decided", "we have chose" =} have chosen, "this volume was placed drop by drop, "was kept supercooled"
Il faut bien prononcer les "s" à la 3ème personne du singulier et après chaque mot au pluriel comme " This agar allows rapid growth",
Attention à la traduction de certains mots comme "this will be the mother suspension". =} "this will be the initial suspension."
N'oublie pas de bien prononcer le morphème –ed : "all the microorganisms **deposited on it"
C'est bien présenté et ton texte est bien écrit.
INTRODUCTION :RETENTION THEME:
The theme we have decided to address is honey. We chose this theme because hives have been installed in our high school (Jean Moulin High School) and we also know that honey has antiseptic, antibiotic, healing and antimicrobial properties. Honey was therefore very affordable with all its properties, so we knew that a lot of handling would be possible.
PRESENTATION OF HONEY :
First of all, the definition of the term "honey" was given in 1969 by the Codex Alimentarius Commission F.A.O.- W.M.S. "Honey is the natural sweet substance produced by bees from the nectar of plants or from the secretions of living parts of plants or from excretions left on them by sucking insects, which they collect, transform, by associating them with specific clean materials, deposit, dehydrate, store and leave to mature in the combs of the hive". Subsequently, honey is essentially made up of a supersaturated solution of various sugars, the two main ones being glucose and fructose. Its water content is on average 17%, usually no more than 20% water. Sugars represent more than 80% of the constituents of honey. Honey is composed of different sugar contents. It contains 75-80% carbohydrates, of which 38% is fructose, 31% glucose, just under 2% sucrose depending on the plants the bees forage, as well as about 7% maltose and various polysaccharides. Nectar honeys are very acidic and have a pH between 3.5 and 4.5, while honeydew honeys are less acidic and have a pH above 4.5.
The colour varies from almost colourless to dark brown. The proportions of the different sugars are variable.
Does high school honey have the same properties as conventional honey?
HYPOTHESES FORMULATED:According to various studies (see attached document) the antiseptic power comes from the high sugar content (glucose-fructose) and also from enzymes such as ex amylase diastases.
→ Do these 2 types of honeys have the same honey content?
Highlighting the antimicrobial power of the 2 types of honey :
→ Does one have a more effective antimicrobial power than the other ?
→ Do they keep the same antimicrobial properties after 1 month, 2 months… if we heat the honeys which of the 2 will be the most resistant to temperature?
Does one have more microorganisms than the other?
TECHNOLOGICAL ACTIVITIES ENVISAGED :
An antibiogram to highlight the antibacterial power of honeys: on a Muller Hinton agar medium with 3 different strains of bacteria (S.Aureus, Pseudomonas, E. Coli). Also by heating the honey because we know that honey is used in the medical field as a dressing for healing wounds for example and for this reason it is pasteurized, heated, so we want to see if its antibacterial power changes or not.
A thin layer chromatography of the sugars to check the presence of glucose fructose and saccharose in the 2 honeys.
A refractometer analysis to determine the water content, which must be less than 18%.
An enzymatic kit to determine the content of sugars, glucose, fructose and saccharose in the honeys.
An enumeration to determine if the honeys contain yeast in small or large quantities.
A pH-metry to determine the pH of the high school honey which is normally acidic, i.e. a pH lower than 7.
PRESENTATION OF A MANIPULATION :
PRINCIPLE:
The count makes it possible to know the number of yeasts present in the honey, whether they are in small or large quantities. For this we will calculate the number of CFU per mL in the honey suspension. We have chosen to inoculate the honeys on two agars, one PCA agar because it is a medium used for the enumeration of microorganisms also called FMAR. It is a medium without inhibitors, so the interest is to promote the development of all the microorganisms deposited on it. As a second agar, we chose an S+C agar, Sabouraud with glucose. This agar allows rapid growth of yeasts and moulds thanks to the presence of nutrients provided by the peptone and glucose.
First we weighed 1 gram of high school honey and 1 gram of commercial all-flower honey. We put the 1 gram of honey in a test tube containing 9 mL of physiological water, this will be the mother suspension.
Then we performed a serial dilution from the stock solution, introducing 1mL of the previous solution with a 1mL graduated pipette into a test tube containing 9mL of physiological water. For the dilutions 10-1, 10-2, 10-3 and 10-4 we seed them twice in kneading boxes. A precise volume of 1 mL was taken with the sterile 1 mL graduated pipette, then this volume was placed drop by drop on an empty Petri dish and 10 mL of PCA agar medium was poured in, and for the second plates the S+C agar medium was kept supercooled but slightly cooled (at a temperature at which the tube can be held in the hand without burning, allowing the survival of the microorganisms, and at which the agar does not take up mass at about 45 °C).
Then we homogenized by keeping the open Petri dish in circular movements (by drawing 8s on the bench). Let the agar cool without moving it in the sterile medium. Finally add a second layer of agar medium on top of the first dry layer and homogenize with circular movements and let it dry. Finally incubate the agars of the two honeys at 37°C for 24 hours. RESULT :
For high school honey agar on PCA agar:
| 10-1 | 10-2 | 10-3 | 10-4 | |
| Microorganism number (FMAT) | 11 | 8 | 5 | 4 |
Calculations:
For the calculation we kept the 10-1 box because the number of colonies is between 10 and 300.
CN(FMAT ; sol miel) = ∑C / V x d x (n1 + (0.1 x n2))
[UFC. mL-1 ] = [UFC / mL x Ø x (Ø + (0.1 x Ø))]
CN(FMAT ; sol miel) = 11 / 1 x 10-1 x (1 + (0.1 x 1))
CN(FMAT ; sol miel) = 100 CFU. mL-1
The volume concentration of FMAT in the honey stock suspension is 100 CFU. mL-1 for high school honey in PCA agar.
N(FTMA ;miel) = CN(FMAT ; sol miel) x ( Vsm / mmiel )
[UFC.g-1] =[ UFC. mL-1 x( mL/ g)]
N(FTMA ;miel) = 100 x ( 10/1 )
N(FTMA ;miel) = 1000 CFU.g-1
The germ content in high school honey is 1000 CFU.g-1.
For high school honey agar on S+C agar and for commercial all-flower honey agar on S+C agar::| 10-1 | 10-2 | 10-3 | 10-4 | |
| Microorganism number (FMAT) | 0 | 0 | 0 | 1 |
As the number of yeasts is nil, no calculation can be made.
For commercial all-flower honey agar on PCA agar:| 10-1 | 10-2 | 10-3 | 10-4 | |
| Microorganism number (FMAT) | 15 | 10 | 6 | 3 |
For the calculation we kept the boxes 10-1 and 10-2 because the number of colonies is between 10 and 300.
CN(FMAT ; sol miel) = ∑C / V x d x (n1 + (0.1 x n2))
[UFC. mL-1 ] = [UFC / mL x Ø x (Ø + (0.1 x Ø))]
CN(FMAT ; sol miel) = 25 / 1 x 10-1 x (2 + (0.1 x 2))
CN(FMAT ; sol miel) = 113.63 CFU. mL-1
The volume concentration of FMAT in the honey stock suspension is 113.63 CFU. mL-1 for the high school honey in PCA agar.
N(FTMA ;miel) = CN(FMAT ; sol miel) x ( Vsm / mmiel )
[UFC.g-1] =[ UFC. mL-1 x( mL/ g)]
N(FTMA ;miel) = 113.63 x ( 10/1 )
N(FTMA ;miel) = 1136.3 CFU.g-1
The germ content in high school honey is 1136.3 CFU.g-1.
CONCLUSION :
To conclude, for PCA agars, high school honey has a lower germ content than commercial honey, high school honey having a content of 1000 CFU.g-1 while commercial honey has a content of 1136.3 CFU.g-1 . For the S+C agars the results are null, indeed there is no yeast present. Following these results we can conclude that high school honey has a lower germ content than commercial honey, which means that high school honey has less microorganisms than conventional honey.
