Journal List > Korean Lepr Bull > v.52(1) > 1139961

Park, Kim, and Kim: Effect of temperature and medium on the viability of Mycobacterium leprae during long term-storage

Abstract

Background

Mycobacterium leprae (M. leprae) is pathogenic bacterium with polymorphic, acid-fast properties and causes leprosy that it is called Hansen's disease. Leprosy can be completely cured using multidrug therapy (MDT), but it is not easy to eradicate leprosy and M. leprae on the planet.

Object

We still do not understand the exact pathogenesis mechanism of leprosy. The main reason is that we cannot grow bacteria in vitro. Therefore, quantitative measurement and damage-free storage of live M. leprae are very important.

Methods

Here, we generated bacteria stocks of M. leprae using HBSS with 0.05% tween 80 or freezing solution 11 months ago and evaluated conditional survival of bacteria by Propidium monoazide (PMA) staining, real-time PCR.

Results

There were assessed for bacteria viability under the conditions of each temperature or medium by delta-Ct level of real-time PCR. We also observed that frozen-stored M. leprae (2.14) compare to refrigerated-stored M. leprae (1.03) was significant decreased delta-Ct in HBSS (P<0.05). However, frozen-stored M. leprae (1.14) was not difference refrigerated-stored M. leprae (0.84) in freezing solution (P=NS). Real-time PCR with SYBR green method was reliable for results and statistical significance, but data for real-time PCR with probe method were unreliable.

Conclusions

Taken together, these results indicated that freezing solution regardless of temperature increase much more bacterial survival. In addition, if use not freezing solution, M. leprae must be stored frozen.

Figures and Tables

Fig. 1

Real-time PCR for differences in stored media

PMA-stained M. leprae was confirmed by real-time PCR of SYBR green method. A) ΔCt of Freezing solution group (Freezing sol., n=7) was significantly decreased at 4℃ compare to HBSS group (HBSS, n=7)(HBSS 2.14 vs Freezing sol. 1.03, *p<0.05). B) ΔCt of Freezing solution group (Freezing sol., n=7) was decreased at −20℃ compare to HBSS group (HBSS, n=7)(HBSS 1.14 vs Freezing sol. 0.84, NS). Samples were stored for 11 months in HBSS or freezing solution (Mean ± S.E.M; *p<0.05; NS, Not significant; each data point is represented on graphs).
klb-52-41-g001
Fig. 2

Real-time PCR for differences in stored temperature

PMA-stained M. leprae was confirmed by real-time PCR of SYBR green method. A) ΔCt of refrigerated group (4℃, n=7) was significantly decreased in HBSS compare to frozen group (−20℃, n=7)(4℃ 2.14 vs −20℃ 1.14, *p<0.05). B) ΔCt of refrigerated group (4℃, n=7) was decreased in freezing solution compare to frozen group (−20℃, n=7)(4℃ 1.03 vs −20℃ 0.84, NS). Samples were stored for 11 months in HBSS or freezing solution. (Mean ± S.E.M; *p<0.05; NS, Not significant; each data point is represented on graphs).
klb-52-41-g002
Fig. 3

Real-time PCR for differences in stored media

PMA-stained M. leprae was confirmed by real-time PCR of probe method. A) ΔCt of freezing solution group (Freezing sol., n=7) was increased at 4℃ compare to HBSS group (HBSS, n=7)(HBSS −0.03 vs Freezing sol. 0.31, NS). B) ΔCt of freezing solution group (Freezing sol., n=7) was increased at −20℃ compare to HBSS group (HBSS, n=7)(HBSS 0.41 vs Freezing sol. 0.6, NS). Samples were stored for 11 months in HBSS or freezing solution (Mean ± S.E.M; NS, Not significant; each data point is represented on graphs).
klb-52-41-g003
Fig. 4

Real-time PCR for differences in stored temperature

PMA-stained M. leprae was confirmed by real-time PCR of probe method. A) ΔCt of refrigerated group (4℃, n=7) was increased in HBSS compare to frozen group (−20℃, n=7)(4℃ −0.03 vs −20℃ 0.41, NS). B) ΔCt of refrigerated group (4℃, n=7) was increased in freezing solution compare to frozen group (−20℃, n=7)(4℃ 0.31 vs −20℃ 0.6, NS). Samples were stored for 11 months in HBSS or freezing solution. (Mean ± S.E.M; *p<0.05; NS, Not significant; each data point is represented on graphs).
klb-52-41-g004
Fig. 5

Summary in this experiment

PMA-stained M. leprae was confirmed by real-time PCR. The results of experiments using real-time PCR of SYBR green showed increase ΔCt deviation compare to real-time PCR of probe method. However, Contrary to SYBR green method, probe method results are unreliable because group of each observed ΔCt.
klb-52-41-g005
Table 1

Results of real-time PCR for SYBR green method

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Table 2

Results of real-time PCR for probe method

klb-52-41-i002

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TOOLS
ORCID iDs

Jin-Ho Park
https://orcid.org/0000-0002-2613-7246

Yun-Ji Kim
https://orcid.org/0000-0002-0003-8880

Jong-Pill Kim
https://orcid.org/0000-0003-0421-6389

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