Streaking an Agar Plate

[Mxsmanic]

I'm confused: if you sterilize the loop before you touch it to the agar plate, doesn't that mean that there will be no bacteria on the plate? Where is the bacteria coming from?

[robin182]

Vebzther - it depends on your standard. Based on water ana colony count below 0-500 is still acceptable.

[82Horror]

touching the agar with the loop just to cool it that's all

[Vebzther]

Pls answer me guys I really need help. I am asked to perform total plate count/aerobic plate count on a pasteurized fruit juice. I need to prove that the product is safe to drink. My teacher told me to make 0, -1, and -2 dilution. If I want to prove that my product is safe thru microbiological reasons does that mean that all my plates should have 0 count? Is it fine to have count at the range of 30-300? Or does 30-300 count mean that my juice product is not safe to consume? TY!

[PatterGuitsIt]

Too bad, no audio but great video.

[hamzie11]

Lol this isnt how you inoculate.

And no touching the agar is not a way to cool the tip, it is a way to make sure it still isnt hot.

and you definitely dont cut it near the centre of the agar and then streak over it

[riool]

Bad example. He is not wearing a white coat and the lid of the petridish should be with the open side on the table. In this way you do not get any dust and bacteria from your white coat (clothes) in the lid.

[Erysipelothrix14]

why is he sterilizing the loop horizontally our professor told us to sterilize it vertically

[unclesam6]

so you don't burn your hand off?

[EedDeryi]

I don't get how that isolates single colonies, if they're all lumped in together and that's why you're trying to seperate them, how does spreading them out result in individual colonies? I'd be grateful for an explanation, I'm studying this at the moment. Thanks:P

[Animechiongster]

@EedDeryi

By spreading the bacteria out u are actually diluting the number of cells per streak. eventually u will only get a few cells in 1 streak and each viable cell will form 1 colony.

[cinbau1]

I think he was just showing general streaking technique- not how to isolate individual colonies. To isolate individual colonies requires a sterile loop for each different colony type and an area of agar to replant the fresh isolate.

Each additional streak will thin out the colonies. =) Hope that helps

[rgiegoldt]

Streaking a plate is like a finger print....everyone does it differently and NONE of them are wrong....the same goes for gram stains.

[D0UKHI]

i think its better to use small loop for streaking and spread he bacterial to 4 part start with clock wise unter u finish the streaking with minimum bacterial colony to identifying the bacterial morphology not like that !!

[akifetti]

i think only one streak is not enough, it must be at least twice....

[Shakeitupyes]

agar-agar is for making food, wtf are you streaking it with a metal rod for O.o

[ilcavalinoboig]

a parte de no llevar guantes, la siembra que realiza es bastante extraña, ademas agujerea el agar en dos ocasiones....

[zensokuracer13]

Gloves are NOT required when handling bacterial cultures. Labcoats are recommended. Just have some good hand hygiene and everybody will be ok.

[nobushino]

LOL!! Lot of angry people out here, with no videos of their own to show how to properly do the procedure. You people love to criticize others by calling them idiots or dumbasses. Is it really necessary? We can say our opinions in a good and civilized manner. So why not post your own videos?

[2zikita]

why leaving the agar plate that open thats the dumbest thing i have seen in microbiology. dumb ass.

[LTown8365]

He's leaving it uncovered to effectively show you how he's doing it. It it was covered, you wouldnt be able to see shit. But yes you're right you shouldnt leave the plate uncovered. You happy?

[lbrayanb]

16 streak plate method is more effective.

[D081]

lol wow whys everyone so angry xD

[rohitfedup]

good work...carry on to add new more educating videos.....

[jackiechan511]

I wonder why the guy isn't wearing gloves. This could be a safety violation

[Orasen28]

dude follow at least bio safety level 2..........or better shut down your lab.

[bigtingz416]

dumbass, if you know and understand the technique of streak plating, youd know that you need to flame your loop in order to kill off some so the consecutive streaks arent as heavily innoculated as the first.

[drsyafiq]

A lot of mistakes i could tell. The biggest is he loop touched the wall of the plate which increase the contamination possibility..

[TiMiSdRuNk]

Yeah i admit the spreading here isn't all that great but he's just doing an example. The one thing i really don't understand is his need to flame the loop so many times as working in a lab you get so many plates and doing it his way would mean working like two hours over everynight...

[CockYaLegS]

You know how this procedure works right?

[triniqueen2560]

whats the point in sterilizing the loops several timesf its touching the same organism?? and dat guy's streaking looks like a 5 yr old's

[hong87k]

he is doing dilution of the bacteria to obtain single,isolated bacteria colonies.

[rubito007]

why cant he finish the agar plate? he is going to end up with a pile of them

[moomoo1337]

Why are you doing this mad streaking, it doesn't make any sense and looks stupid, its innoculum well , change loop (or if you are being stupid use burn loops) then 4 streaks then either or a wiggle or 4 more streaks then a wiggle. I can streak over 500 plates a day in work and it works just fine for me, everyone else i know in working laboratories uses this method as well as it being part of standard practice.

[59arkady]

Please; why are you touching the sterilized loop to the agar (post inoculation) before you start your streak?

Thank you.

[cegodsey]

You can wait several seconds to make sure the loop is cool, or you can touch it to the agar to cool it.

[59arkady]

Used this in my class - the example was a great help to me.

[nauolin]

because you need to cool it, you dont want to kill the other colonies that you had cultured

[nauolin]

thats why he put the loop in the agar before streaking:

answer to 59arkady =)

[The0leon]

@59arkady  to cool down the wire loop so that it will not kill the bacteria

[whosshane]

no point of sterilizing metal loops...just get sterile plastic ones. 3 sections...streak first section, pull from the section across the plate, turn; pull from 2nd section down the plate.

[ImSpartacus811]

Why do you need to streak a plate? I dont understand how this would isolate a single bacteria cell to make a pure culture. I assume that's what youre trying to do.

I'm sorry if I'm insulting you in any way, I am trying to learn more about bacteria cultung and identification methods. I have a sci fair project and theres not too many places that flat out explain why streaking and other things are done.

[kileu]

By flaming the loop between streaks, less bacteria is smeared. This allows for a smaller amount of bacteria to be separated which will hopefully lead to the growth of individual colonies.

[ImSpartacus811]

Thank you. Didn't know.

Lol, since that comment, I have finished my science project. I got helped by someone my dad works with. Found out I wouldn't have to do any testing at all. Just contact plates (which are insanely simple) and a little over a week on top of the fridge.

It's kind of depressing that I learned a bunch of college level stuff about micro (though i prolly couldn't demonstrate in in real life), and I didnt have to use any of that knowledge.

[kileu]

Well, it's very interesting and you can always impress people with any knowledge that is gained. ^^

[moomoo1337]

Its all about distance, you are more likely to isolate what you are looking for if you take it across its preferred medium for a longer length, so it can outperform competing bacteria during its incubation period

[Kabulay]

Stroke yo moma, you suck!

[cegodsey]

Actually, this is the method used by the US Navy.

[Kabulay]

Its far better to make right strokes..! 5-5-5-5..!

And you are not sterilizing proberly, you should hold the loop more in the flame, not just the tip!

[cegodsey]

whatever!  Stroke this!

[JaCalsGal]

@cegodsey lol!