Hello mush fam....long time lurker and first time poster here. I've gained so much knowledge from these forums (thank you very much) so I figured it was time to reciprocate and write up a tek for you guys/gals to use in order to make your own wide mouth, modded, plastic grain spawn lids with SFD's and injection ports. After experimenting with a modded lid that has an SFD (synthetic filter disk) and a slightly modded plastic lid (no GE holes) with an injection port I decided to combine the best of both worlds.

After a few trials I concluded that the jars with the SFD lids colonized faster compared to the plastic lids with an injection port that were loosened (no mod style) in order to create gas exchange. What I didn't like about the modded SFD lids is the fact that I would have to open them in my SAB in order to inoculate them as well as the fact that the lids/rings are susceptible to rust over time.
The picture below shows a different variety of cubes in each jar, but each variety practically grew at the same rate when their liquid culture was placed onto an agar plate. The jar with the plastic lid may have had a little more LC injected on top vs the side, but it still didn't colonize faster than the modded SFD lids. **The difference in colonization may be due to that fact that I didn't open up the plastic lid enough, or it was opened too much. However, I did use both varieties in each type of jar and the results were the same (modded SFD colonized faster). Overall, I'd rather not worry about opening my jars or how much I need to unscrew the lid due to the fact that I use an SAB (still air box).

Tools and equipment needed: *Wide mouth plastic lids *Heavy duty injection ports (the orange ones). DO NOT use the smaller, gray injection ports since they are weaker and do not reach down as far below the lid. *Powered Drill *1/2" forstner drill bit (for the self healing injection ports) *1/8" drill bit for the GE (gas exhange) holes *Wide mouth synthetic filter disks (SFD's)
Start off by using the 1/2" inch forstner bit and drilling a hole right in the center of your plastic lid. The lid should have an indention that marks the center. I screwed the lid onto the jar and drilled the hole.

After your 1/2" hole is drilled in the middle of the lid place your SFD underneath the lid so you can trace a circle onto the SFD to cut out another 1/2" hole in the SFD. You can measure the SFD without the lid in order to find the center of the circle, but I found this method to be easier and less time consuming since I didn't have a protractor handy.

Use the same 1/2" bit to drill out the center of the SFD that you just traced (or measured). I figured that it was best to use the same SFD with the lid it was traced from in order to eliminate any discrepancies between the two holes. As far as drilling the SFD's is concerned, I placed a towel down with a few layers of cardboard on top in order to prevent the bit going through the SFD and scratching my table.

Make sure everything lines up! You should be able to place the disk underneath the lid and insert your HD injection port with no modifications to either hole. IF your SFD hole doesn't line up exactly with the hole in the lid that shouldn't be a big deal as long as your HD injection port creates a good seal with the lid. You can use RTV silicone here if you wish, but if you use a 1/2" forstner bit to drill your hole then the HD injection port should create a pretty nice seal with the lid. In other words, if your injection port slips right through the 1/2" hole in your lid then your seal isn't worthy. You should have to pinch and pull the injection port through both holes in order for the HD injection port to create a good seal.

This step can be done before or after the previous steps, but you need to drill holes for gas exchange. I drilled four 1/8" holes in my lid at 3, 6, 9 and 12 o'clock. Make sure that you drill these holes through the plastic lid only, NOT the SFD. The area of four 1/8" inch holes equals the same area as one 1/4" inch hole. After 5 holes (one 1/2" hole in the center and four 1/8" holes in each quadrant) have been drilled into your lid and one 1/2" hole drilled in your SFD you should have a finished product similar to this. The SFD is underneath the lid

DISCLAIMER: I have yet to use these particular lids, but they should hold up well in the PC and eliminate the need to unscrew your modded metal lids. Also, they won't oxidize (rust).
I made these lids to use with clean liquid cultures, but you can definitely make them without the injection port to use in place of the modded metal lids. I'll post pics of colonization as soon as I can. Thanks and mush love to you all!
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