Shane Vontelin van Breda

16 Questions 44 Answers 0 Followers

Questions related from Shane Vontelin van Breda

Can someone suggest an alternative SEM preparation method for bacteria?

I am trying to prepare Mycobacterium tuberculosis for SEM analysis. This is my current method, basically summarized: Fix cells in buffer + formaldehyde and glutaraldehyde, rinse in buffer, fix in...

11 November 2014 900 3 View

Could I use stoichiometry ratios to predict MICs for different CFU/ml?

I have determined MIC at > 90 % cellular inhibition using 1 x 10^5 CFU/ml for MTB. I would like to predict how much of my antimicrobial peptide I would require to achieve the same inhibition...

09 September 2014 3,373 3 View

What is the best way to determine the effect a cationic peptide would have on the cell wall of bacteria?

I am investigating the effect of a cationic peptide on M. tuberculosis. I am using various microscopy techniques such as TEM, SEM, AFM and CSLM. Which of these two methods would be the best? 1)...

08 August 2014 9,087 10 View

Can anyone suggest how to deal with low cell titers and TEM?

I hope someone could help with this question. I am trying prepare bacterial cells for TEM analysis after treatment with a cationic antimicrobial peptide. I determine my MIC in 96 well microtiter...

06 June 2014 2,226 1 View

Could the following storage and culture method affect my MIC results?

I am determining MICs for M. tuberculosis using the alamar blue method described by Franzblau et al. I have had good success up until now. I am experiencing some variation in my MICs. I grow my...

04 April 2014 7,352 8 View

Derivatization of polymyxins using FMOC - Cl?

I am attempting to derivatize polymyxins using FMOC - Cl. I run the derivatives on UPLC, but unfortunately I am struggling to determine which peaks are polymyxins. Briefly, using a vacuum...

03 March 2014 4,360 5 View

What is the difference in Mycobateria growth in flat vs v (conical) - well shaped 96 - well microtiter plates?

I have been determining MICs for M. tuberculosis using 96 - well microtiter plates, flat well shape. After five days, I confirm positive growth by adding alamar blue to my controls. Recently I...

03 March 2014 2,652 1 View

What is the difference in growth rates for MTB during MIC determinations?

I hope someone could explain this observation to me and how to possibly rectify this issue. I am determining MICs for a peptide against MTB. I started off with H37Ra. I incubate my cultures on...

03 March 2014 9,895 14 View

Any possible explanations for why Zinc is affecting peptide MICs against M. tuberculosis?

I have noticed that increasing the concentration of Zn2+ in my bacterial media improves the MICs of an anionic peptide I am investigating against M. tuberculosis H37Ra. I have used starting...

02 February 2014 6,333 15 View

What could explain these different MIC observations for M. tuberculosis?

When I use cells grown to mid - log phase, immediately out of the incubator, I obtain a MIC of 200 ug/ml for a peptide I am investigating. When I use mid - log cells that have been removed from...

01 January 2014 5,380 25 View

Antibiotic potency?

I am investigating MICs for colistin (15000 Units/mg) and polymyxin B (8000 IU/mg). Up until now I have just been weighing the antibiotics and reporting the MICs as mg/L. I am confused by this...

12 December 2013 5,760 8 View

Does anybody have experience with Alamar Blue?

I have noticed that my controls containing Alamar Blue + media only are reduced by 10% (expected due to loss of buffering capacity [comparing to Alamar blue + media with cells + no test...

11 November 2013 5,447 5 View

Does anybody know which Mycobacteria are catalase negative?

When performing the catalase test for Mycobacteria and obtaining a negative result, does that rule out any presence of MOTTs/NTMs. My negative result is positive for M. tuberculosis (MPT64...

11 November 2013 9,615 14 View

Does anybody know when mid - log phase of growth is reached for MTB when growing on 7H10 agar enriched with OADC?

When is mid - log phase of growth for MTB reached when growing on a solid media like 7H10 + OADC at 37 degrees Celsius? In general, is it three weeks? When I grow MTB in liquid media, I...

11 November 2013 4,043 2 View

Does anybody know if M. tuberculosis could utilize sucrose as a carbon source?

I would like to grow MTB in media containing sucrose as a carbon source (substituting glycerol [for reasons I won't go into right now]). But will it grow? I have not been able to come across any...

10 October 2013 2,164 21 View

Could somebody help me with interpreting M tuberculosis MIC with differences determined in different growth media?

I have a problem interpreting my MIC (minimum inhibitory concentration) results determined by the the alamar blue assay. Briefly, I am investigating the MIC of a cationic peptide against M....

10 October 2013 4,384 7 View