나노바이오실험(1) A 자료) 1. Sampling, Spreading, Cell Counting

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1. Sampling

실험의 필요성에 맞는 적절한 sample을 구하는 것이 중요합니다. 화장실 변기에서 채취한 sample은 균이 배양되지 않았는데, 이는 채취 과정에서 오염되었거나 균의 수가 매우 적었을 수 있습니다. 두 번째 sample인 흙에서는 colony가 관찰되었지만, 희석 배율에 따른 결과가 일관되지 않았습니다. 이는 시료 내 이물질로 인한 희석 과정의 오류, 도말 과정에서의 오염, 열 처리 불충분 등이 원인으로 추정됩니다.
2. Serial dilution

미생물의 수를 측정할 때 시료를 10배씩 단계적으로 희석하는 serial dilution 방법을 사용했습니다. 희석한 시료를 배지에 배양하여 colony 수를 세고, 희석 배수를 곱하여 원액의 미생물 수를 계산할 수 있습니다. 이번 실험에서는 10-7배까지 희석하여 배양했지만, 일부 배율에서 예상과 다른 결과가 나왔습니다.
3. CFU (Colony-Forming Unit)

CFU는 미생물학에서 눈에 보이는 박테리아나 균류의 숫자를 측정하는 단위입니다. 액체 시료의 경우 CFU/mL, 고체 시료의 경우 CFU/g으로 표현합니다. 이번 실험에서는 희석 배수 10-2의 colony 수 186개를 기준으로 CFU를 계산하여 1.86 × 105 CFU/mL로 도출했습니다.

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1. Sampling

Sampling is a fundamental concept in various fields, including scientific research, quality control, and data analysis. It involves selecting a subset of a population or a larger set of data to make inferences or draw conclusions about the entire population or dataset. Proper sampling techniques are crucial for ensuring the validity and reliability of research findings and decision-making processes. The key aspects of sampling include the selection of a representative sample, the determination of an appropriate sample size, and the implementation of unbiased sampling methods. Depending on the research objectives and the characteristics of the population, different sampling techniques, such as random sampling, stratified sampling, or cluster sampling, may be employed. Effective sampling strategies can help researchers or analysts overcome the practical limitations of studying an entire population, while still providing accurate and meaningful insights. By carefully designing and executing sampling procedures, researchers can make informed decisions, test hypotheses, and draw reliable conclusions from the available data. Furthermore, the concept of sampling is not limited to scientific research; it is also widely used in various industries, such as quality control, market research, and public health monitoring, to ensure the efficient and cost-effective assessment of product quality, consumer preferences, or disease prevalence. Overall, the understanding and application of sampling techniques are essential for generating reliable and actionable insights from data, ultimately contributing to the advancement of scientific knowledge, the improvement of products and services, and the informed decision-making process.
2. Serial dilution

Serial dilution is a widely used technique in various scientific disciplines, particularly in microbiology, biochemistry, and analytical chemistry. It involves the systematic dilution of a sample or solution to obtain a series of samples with decreasing concentrations of the target analyte or microorganism. The primary purpose of serial dilution is to enable the quantification or enumeration of a specific component within a complex mixture. By creating a series of dilutions, researchers can accurately measure the concentration or number of the target substance, which is often essential for various applications, such as: 1. Microbial enumeration: In microbiology, serial dilution is used to determine the number of viable microorganisms (e.g., bacteria, fungi) in a sample by counting the number of colony-forming units (CFUs) on agar plates. 2. Enzyme activity assays: In biochemistry, serial dilution is employed to measure the activity of enzymes by testing their ability to catalyze a specific reaction at different substrate concentrations. 3. Analytical quantification: In analytical chemistry, serial dilution is used to prepare calibration standards for the quantification of target analytes, such as drugs, toxins, or environmental pollutants, using techniques like spectrophotometry or chromatography. The accuracy and precision of serial dilution are crucial, as the results can directly impact the reliability of subsequent analyses and the validity of research findings. Careful attention to factors such as pipetting technique, volume measurements, and the use of appropriate diluents is essential to ensure the integrity of the dilution series. Overall, serial dilution is a powerful and versatile technique that enables researchers to obtain quantitative information about the concentration or abundance of specific components within complex systems, contributing to the advancement of scientific knowledge and the development of various applications in diverse fields.
3. CFU (Colony-Forming Unit)

CFU, or Colony-Forming Unit, is a fundamental concept in microbiology that is used to quantify the number of viable microorganisms in a sample. It is a widely used method for enumerating the population of bacteria, fungi, or other microorganisms in various applications, such as food safety, environmental monitoring, and clinical diagnostics. The CFU is determined by counting the number of colonies that develop on a solid growth medium, such as agar plates, after inoculating the sample and allowing the microorganisms to grow and form visible colonies. Each colony is assumed to have originated from a single viable cell or a clump of cells, and the number of colonies is used to calculate the concentration of the microorganisms in the original sample. The CFU method is advantageous because it provides a direct measure of the number of viable microorganisms, which is often more relevant than the total cell count, as it reflects the population of cells that are capable of growth and reproduction. This information is crucial in various contexts, such as: 1. Food microbiology: Determining the microbial load in food samples to assess quality, safety, and shelf-life. 2. Environmental monitoring: Quantifying the presence of indicator organisms (e.g