Lenticules for the control of quantitative methods in food microbiology

Abstract

A .A . C O DD , I . R. RI C HA RD S ON AN D N. AN D RE WS . 1998. Control dried organisms as lenticules are a dependable and convenient alternative to wet cultures for quality assurance and process controls in routine food microbiology. Lenticules are designed to give a fixed, reproducible inoculum over an extended period of time without loss of cultural characteristics or viability. During a period of 23 months, 596 paired counts were performed by both Miles and Misra and spiral plating techniques on lenticule controls. Correlation between the two methods and within batches was excellent. Only 14 counts (2·5%) fell outside the standard operating limit of 0·5 log 10 . All were within 1·0 log 10 . On two separate occasions, replicate runs were performed on five reconstituted lenticules from a batch. The counts obtained showed variation within and between lenticules only slightly in excess of what is expected by chance. Lenticule replicates performed by three other laboratories also produced satisfactory results. It is thought that lenticules could improve the accuracy of total plate counts and lead to a better standardization of quantitative methods in food microbiology within and between laboratories.

Genetic stability of strains preserved on LENTICULE discs and by freeze-drying: a comparison using fluorescent amplified fragment length polymorphism analysis

“…However, it is essential to evaluate the effect of LENTICULE disc production and processing on the viability, growth characteristics and stability of the microbial cells. Previous studies have confirmed the suitability of lenticulation with respect to reproducible inoculum size without changes to the colonial morphology, and cultural and biochemical characteristics of the bacteria (Codd et al, 1998). In this study we have utilized FAFLP analysis of the gross microbial chromosome to detect potential processassociated mutations arising from LENTICULE disc production compared with the gold standard FD method.…”

Human Enteric Viruses Occurrence in Shellfish from European Markets

“…Data summarised in Table 1 (Codd et al 1998) that had been loaded with around 10 3 genome copies norovirus (GGI and/or GGII) and/or 1 9 10 5 -8 9 10 4 genome copies of hepatitis A virus (Anon 2008b). Of the 28 laboratories, 27 returned results within the specified time frame, amongst which 17 NRLs and 10 non-NRL and third country laboratories, i.e.…”

Assessment of the stability of cell-surface components of microorganisms by MALDI-TOF-MS following preservation on lenticule discs

“…The mechanism for the procedure relies on the preservative properties of trehalose on membranes, proteins and biomolecules (Prior et al, 2005). The lenticule disc process has the advantage of providing accurate homogeneous quantitative cultures (Codd et al, 1998); freeze-drying is more commonly used for qualitative controls. Consequently, it is essential to establish that the process enables retention of microbial expression and cellular properties.…”