Antibacterial Activity of Polymeric Membranes Against Antibiotic-Resistant Bacteria

Kai Shen Choong Author

07/31/2020 Added

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Studying the Antibacterial Activity of Polymeric Membranes against Antibiotic-resistant Bacteria Kai Shen Choong This project is to study the introduction of sulfonated polysulfone membranes to ampicillin-resistant E. Coli.

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[00:00:01.224]Hello everyone, my name is Kai.
[00:00:03.488]I’m from the College of Engineering,
[00:00:05.769]Department of Chemical and Biomolecular Engineering,
[00:00:09.680]and today I’m going to talk about
[00:00:11.850]my UCARE project with the title of
[00:00:14.181]Studying the Antibacterial Activity of Polymeric Membranes
[00:00:18.246]against Antibiotic-resistant Bacteria.
[00:00:21.840]Let’s get started.
[00:00:23.076]Bacteria had existed for ages
[00:00:25.521]and gave us human beings problem.
[00:00:27.897]We solved that by creating antibiotics for the bacteria.
[00:00:31.612]Over time, as we are trying to protect ourselves,
[00:00:34.402]we overuse and misuse antibiotics.
[00:00:37.467]This is why there are so many antibiotic-resistant bacteria today
[00:00:44.634]because the bacteria itself
[00:00:46.224]mutate and evolve to protect themselves.
[00:00:49.553]From some studies, it has been shown that
[00:00:53.394]multi-block sulfonated polymers could inactivate more than 99%
[00:00:57.964]of Gram-positive and negative bacterial strains within five minutes.
[00:01:02.730]So, the aim of this project is
[00:01:04.592]to study the antibacterial activity of sulfonated polymers,
[00:01:09.462]mainly polysulfone and sulfonated lignin,
[00:01:14.036]against ampicillin-resistant E. coli.
[00:01:18.426]So, I formed the membranes
[00:01:20.590]using solution casting method
[00:01:22.835]and the materials used were
[00:01:25.805]polysulfone (PS),
[00:01:28.085]sulfonated polysulfone (SPS),
[00:01:31.983]PS and lignin sulfonate (LS)
[00:01:34.331]in a ten to one ratio
[00:01:36.516]as well as SPS with LS in a ten to one mass ratio.
[00:01:42.607]The casted membranes were then
[00:01:44.751]cut into 1 cm by 1 cm pieces.
[00:01:47.591]Then, the bacteria are cultured using
[00:01:52.460]ampicillin-resistant E. coli (pSSBIO2)
[00:01:57.144]grown following the standard protocol.
[00:02:00.538]It was cultured in Luria-Bertani (LB) media
[00:02:04.760]and incubated at 37 degree Celsius overnight.
[00:02:09.080]A single colony was then transferred
[00:02:11.390]into new LB media and
[00:02:14.179]incubated for 37 degree Celsius overnight.
[00:02:18.649]So, it’s time to test the membranes.
[00:02:21.525]The membranes were added to the bacteria cells
[00:02:24.457]and incubated for four hours
[00:02:27.913]then the treated bacteria were
[00:02:29.793]transferred into LB media to grow for 3 hours.
[00:02:34.537]Finally, the absorbance at 600 nanometers
[00:02:38.833]was measured and the antibacterial activities of the membranes were calculated using Equation 1,
[00:02:49.612]shown at the bottom of the materials and methods section.
[00:02:54.772]After those experiments, this is what I got.
[00:02:58.152]Figure 1 shows the chemical structures
[00:03:00.702]of the polymer that I used
[00:03:02.960]which were SPS and LS,
[00:03:05.432]if it is a PS then the sulfonate group in SPS is just a hydrogen.
[00:03:13.648]The image shown in the middle of Figure 1
[00:03:16.650]is an example of a casted membrane
[00:03:20.404]this one here is a SPS membrane in 1 cm by 1 cm dimension.
[00:03:25.811]Keep in mind that
[00:03:27.130]all the membranes were about
[00:03:29.341]60 micrometers thick.
[00:03:32.536]The table next to it shows the membrane
[00:03:36.353]and its ion-exchange capacity.
[00:03:39.524]Figure 2 here shows a
[00:03:41.954]schematic of the methods used.
[00:03:44.034]As mentioned before, the bacteria were
[00:03:46.528]treated with the membranes for four hours.
[00:03:50.938]And then, 50 microliters of the treated cells
[00:03:55.568]were added to LB media for 3 hours at 37 degree C.
[00:04:01.321]Figure 3 shows the colony forming units (CFUs) for each trial.
[00:04:09.941]In A, it is the untreated one,
[00:04:14.119]which looks like a hot mess.
[00:04:16.337]And in B, this is the one which was treated with PS.
[00:04:22.217]In C, it is treated with PS with LS.
[00:04:26.057]In D, it is treated with SPS and
[00:04:29.377]finally in E, it is the one treated with SPS with LS.
[00:04:35.437]Here we can see that the hot messes
[00:04:38.419]were reduced after being treated by the membranes.
[00:04:42.689]The samples that were treated with PS and PS with LS membranes
[00:04:51.113]did not cause much or any reduction in bacterial colonies
[00:04:56.466]as the plates were not clear.
[00:04:59.059]However, the samples that were treated with SPS and SPS with LS membranes
[00:05:06.067]showed great reduction in bacterial colonies
[00:05:09.117]as the plates were almost clear.
[00:05:11.650]The absorbances of untreated sample and treated sample
[00:05:15.812]of each trial were also measured and used
[00:05:20.236]in equation 1 to calculate the growth inhibition.
[00:05:23.768]Figure 4 shows the results for it.
[00:05:27.575]PS and PS with LS did not possess much growth inhibition,
[00:05:34.205]they were about 0% and 3%
[00:05:37.479]but, SPS and SPS with LS showed about 98% and 100% growth inhibition.
[00:05:48.570]This agrees in the previous part,
[00:05:50.460]which was the CFU reduction.
[00:05:53.450]So, SPS and SPS with LS membranes are effective
[00:06:00.388]against antibiotic-resistant bacteria.
[00:06:04.400]If we take a closer look into
[00:06:06.542]the table on the left column of results section
[00:06:10.040]and the graph on the right column of results section,
[00:06:14.235]we can corelate its ion-exchange capacity to the growth inhibition
[00:06:20.463]as the trend looks similar.
[00:06:23.109]This is helpful as more trials with
[00:06:25.589]different ratios of SPS and LS or PS with LS,
[00:06:32.003]in which produces membranes with varying ion-exchange capacity,
[00:06:40.149]are needed to be done
[00:06:43.485]to complete the function in the future
[00:06:45.937]to further understand the relationship between
[00:06:49.211]ion-exchange capacity and its antibacterial activity
[00:06:53.047]using polysulfone membranes.
[00:06:57.625]In conclusion, the membranes with
[00:07:01.061]60 micrometers thick were casted successfully
[00:07:04.511]using solution casting methods.
[00:07:07.111]Sulfonated membranes showed
[00:07:10.011]antibacterial activity against antibiotic-resistant E. coli.
[00:07:15.791]Antibacterial activity of membranes
[00:07:19.361]was a function of ion-exchange capacity,
[00:07:23.245]like the membranes with higher
[00:07:26.230]ion-exchange capacity showed
[00:07:28.459]higher antibacterial activity
[00:07:30.966]against ampicillin-resistant E. coli.
[00:07:35.778]The final point that I want to point out is that
[00:07:39.716]SPS and SPS with LS membranes inhibited
[00:07:46.692]growth rate of bacteria cells around 100%.
[00:07:51.972]I’d like to end this off with some acknowledgments.
[00:07:54.662]I’d like to thank Doctor Dishari for her encouragement
[00:07:57.921]in order to complete the work.
[00:08:00.110]I would also like to thank the two graduate students from Dr. Dishari’s group;
[00:08:04.320]they are Ehsan Zamani and Seefat Farzin
[00:08:08.248]for their support and guidance throughout the experiments.
[00:08:11.396]Without them, this project wouldn’t be a success.
[00:08:14.442]With that said, I’d like to end this presentation.
[00:08:18.068]Thank you all for listening!

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Antibacterial Activity of Polymeric Membranes Against Antibiotic-Resistant Bacteria

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