Inoculating Loops and Needles
Inoculating loops and needles (sometimes called microstreakers or inoculating wands) are hand-held devices for inoculating plated or tubed growth media with microorganisms such as bacteria or yeasts prior to incubation, multiplication and growth. The inoculum is typically streaked onto, or stabbed into, solid agar-based media, or simply introduced and dispersed into liquid media. Inoculating loops and needles are also useful for sampling and transferring small quantities of microorganism prior to further analysis, microscopic examination, or serial dilution.
Inoculating loops and needles consist of a handle with a terminal loop or needle which is designed to pick up and transfer a small quantity of inoculum (typically 1 to 10μL) from a donor culture to the growth medium of choice. Some loops are calibrated and colour-coded to transfer semi-quantitative amounts of inoculum.
What are the different types of inoculating loops and needles?
Inoculating loops and needles are available as fully disposable items made entirely from plastics such as polystyrene or polypropylene for strength and flexibility. These plastic versions are usually supplied presterilised by gamma irradiation in single or multiple packs. Alternatively, they may be constructed from reusable, autoclavable and flame-sterilisable materials, such as aluminium or stainless-steel handles with integral or interchangeable loops or needles made of platinum, nichrome or tungsten.
Inoculating loops and inoculating needles are invaluable items in any laboratory or workplace performing routine or occasional microbiological culture or maintenance, microbiological QA/QC, microbiological identification, or MIC (minimal inhibitory concentration) assessment of novel antibiotics, pharmaceuticals, or biocides.