Quantification of citrate lyase by enzyme-linked immunosorbent assay for determining the population of Lactococcus lactis subsp. Lactis biovar diacetylactis in pure and mixed cultures

David, P. F.; Boquien, Clair‐Yves; Nakache, F.; Bassit, N.; Hartley, Donna F.; Paraf, A; Corrieu, Georges

doi:10.1007/s002530050521

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“…On the other hand phenyl ethyl alcohol agar plates are used to estimate gram positive organisms such as B. subtilis (DuTeau et al [ 1998 ]). Enzyme linked immunosorbant assay can be used to quantify specific organism in a biofilm or mixed cultures (Bauer-Kreisel et al [ 1996 ], David et al [ 1995 ]). Terminal-Restriction fragment length polymorphism has also been used to specifically quantify cells in cultures containing more than two cultures (Schmidt et al [ 2007 ]).…”

Section: Introductionmentioning

confidence: 99%

Study of CFU for individual microorganisms in mixed cultures with a known ratio using MBRT

Nandy

Venkatesh

2014

AMB Expr

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Determination of metabolically active cell count is an important step in designing, operating and controlling fermentation processes. It’s particularly relevant in processes involving mixed cultures, where multiple species contribute to the total growth. The motivation for the current study is to develop a methodology to estimate metabolically active cell counts for the individual species in a mixed culture with approximate equal numbers. Further, the methodology should indicate the presence of a contaminant in short time periods since in the agar plate methods used frequently it takes about 24 h. We present a methodology based on the rate of Methylene blue (MB) reduction to evaluate total count of metabolically active cells. The standard curve relating the slope of MB reduction and CFU of the individual species could be used to measure the metabolic activity of each species in the mixed culture. The slope of MB reduction could also be used to obtain the growth rate of individual species in a mixed culture and that of the total cell count. These measurements were achieved in less than 6 minutes during the growth of the cells. Evaluating the metabolic activity of individual species in a mixed culture is tedious, difficult and time consuming. The Methylene Blue dye Reduction Test (MBRT) presented here is capable of quickly estimating colony forming units (CFU) of individual species in a mixed culture if the ratio of the numbers of cells is known. The method was used to dynamically detect the occurrence of a contaminating microorganism during fermentation. The protocol developed here can be adapted to applications in processes involving mixed cultures.

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