# Attempts at growing hydrogen-oxidizing bacteria

**URL:** <https://forum.amybo.org/t/attempts-at-growing-hydrogen-oxidizing-bacteria/111>\
**Category:** Bugs\
**Created:** [4 January 2025 14:24 UTC](https://forum.amybo.org/t/attempts-at-growing-hydrogen-oxidizing-bacteria/111 "2025-01-04T14:24:43Z")\
**Posts on this page:** 1\
**Showing post:** 5

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**Author:** ![Martin](https://forum.amybo.org/user_avatar/forum.amybo.org/martin/32/19_2.png) [@Martin](https://forum.amybo.org/u/Martin)\
**Post date:** [9 January 2025 01:57 UTC](https://forum.amybo.org/t/attempts-at-growing-hydrogen-oxidizing-bacteria/111/5 "2025-01-09T01:57:28Z")

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> [@gerrit](#):
>
> For my next experiment I think I’ll attempt a soil/sediment sample, as there’s probably a higher chance to find HOB in there.

Yes, I think soil/sediment probably makes most sense. I’m thinking about getting a large enough sample that we can drain water and test it’s ionic strength to avoid osmotic shock.

> [@gerrit](#):
>
> Looks like there may have been a very small amount of biofilm growing on the cathode? Or am I being too much of an optimist now?

I can’t see in this photo if its bubbles or what could be biofilm. Is it just me or is your cathode bolt looking rather darker than the portion above the cap?

Also I notice the ‘rusty’ discolouration on your anode. I have just checked the specs of my [original bolts](https://amzn.eu/d/aqf8Igo) and they were A2 like your [304SS bolts](https://www.ebay.co.uk/itm/234853770967), so I have bought a set of these [A4 316 bolts](https://amzn.eu/d/0VfpKFj) as I couldn’t find any 316L’s. I should probably have gone up a grade to duplex, the prices aren’t unreasonable, but M6 is the smallest, and the options I can find are either [full thread hex head](https://www.westfieldfasteners.co.uk/Bolts-Screws-Metric/Hex-Bolt-Full-Thread-M6x60-Duplex-1.4462-Stainless.html) or [cap head without full thread](https://www.accu.co.uk/metric-cap-head-screws/642067-SSC-M6-60-DX).

> [@gerrit](#):
>
> I guess you could do this manually or with the peristaltic pumps.

I was definitely meaning with the persitaltic pumps. Start with pure sample in the vial and operate in turbidostat mode feeding in your nutrient solution. If you didn’t see any rise in OD, you’d want to do a small manual pump activation to get the trace nutrients in - GPTo1 reckons you’d only want to wait 1-2 hours for this (which seems way too rapid IMHO) and is worried that the HOB may starve if left without trace nutrients for 6h.

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