Lactococcus lactis F10, isolated from freshwater catfish, produces a bacteriocin (BacF) active against Staphylococcus aureus, Staphylococcus carnosus, Lactobacillus curvatus, Lactobacillus plantarum, and Lactobacillus reuteri. The operon encoding BacF is located on a plasmid. Sequencing of the structural gene revealed no homology to other nisin genes. Nisin F is described.

No abstract

The occurrence of microorganisms in water due to contamination is a health risk and control thereof is a necessity. Conventional detection methods may be misleading and do not provide rapid results allowing for immediate action. The quantitative polymerase chain reaction (qPCR) method has proven to be an effective tool to detect and quantify microorganisms in water within a few hours. Quantitative PCR assays have recently been developed for the detection of specific adeno- and polyomaviruses, bacteria and protozoa in different water sources. The technique is highly sensitive and able to detect low numbers of microorganisms. Quantitative PCR can be applied for microbial source tracking in water sources, to determine the efficiency of water and wastewater treatment plants and act as a tool for risk assessment. Different qPCR assays exist depending on whether an internal control is used or whether measurements are taken at the end of the PCR reaction (end-point qPCR) or in the exponential phase (real-time qPCR). Fluorescent probes are used in the PCR reaction to hybridise within the target sequence to generate a signal and, together with specialised systems, quantify the amount of PCR product. Quantitative reverse transcription polymerase chain reaction (q-RT-PCR) is a more sensitive technique that detects low copy number RNA and can be applied to detect, e.g. enteric viruses and viable microorganisms in water, and measure specific gene expression. There is, however, a need to standardise qPCR protocols if this technique is to be used as an analytical diagnostic tool for routine monitoring. This review focuses on the application of qPCR in the detection of microorganisms in water.

The harvesting of rainwater is gaining acceptance among many governmental authorities in countries such as Australia, Germany, and South Africa, among others. However, conflicting reports on the microbial quality of harvested rainwater have been published. To monitor the presence of potential pathogenic bacteria during high-rainfall periods, rainwater from 29 rainwater tanks was sampled on four occasions (during June and August 2012) in a sustainable housing project in Kleinmond, South Africa. This resulted in the collection of 116 harvested rainwater samples in total throughout the sampling period. The identities of the dominant, indigenous, presumptive pathogenic isolates obtained from the rainwater samples throughout the sampling period were confirmed through universal 16S rRNA PCR, and the results revealed that Pseudomonas (19% of samples) was the dominant genus isolated, followed by Aeromonas (16%), Klebsiella (11%), and Enterobacter (9%). PCR assays employing genusspecific primers also confirmed the presence of Aeromonas spp. In addition, on one sampling occasion, Giardia spp. were detected in 25% of the eight tank water samples analyzed. This study highlights the diverse array of pathogenic bacteria that persist in harvested rainwater during high-rainfall periods. The consumption of untreated harvested rainwater could thus pose a potential significant health threat to consumers, especially children and immunocompromised individuals, and it is recommended that harvested rainwater be treated for safe usage as an alternative water source. R ainwater harvesting (RWH) has been described as an alternative improved water source, as this technology could assist in the provision of water directly to households for drinking and domestic purposes (1). Communities are also able to capture and store rainwater for utilization in small-scale productive activities, such as vegetable gardening, which could make a positive contribution toward food security for individuals from lower socioeconomic groups (2). In addition, low economic growth and the effects of climate change have compelled many governments and water authorities worldwide to rely on the process of harvesting rainwater as an alternative source of water (3).A limited number of qualitative studies (4) have been conducted on the usage of rainwater for domestic and potable purposes, and while some studies have determined that harvested rainwater is safe for drinking purposes without prior treatment (5, 6), a few studies have, however, shown that harvested rainwater is, in fact, not suitable for potable purposes (7, 8, 9, 10, 11). As rainwater is collected from roof surfaces, pathogenic organisms that are found in bird feces, insects, mammals, reptiles, and other debris may be flushed into the tanks via the gutters and the tank inlet systems. This phenomenon could pose serious human health risks (12), and between 1978 and 2006, six incidents of disease related to rainwater were reported (10,13,14).Indicator organisms, such as fecal coliforms and Escherichia coli, ...

Aims:  To determine the antimicrobial activity of nisin F against Staphylococcus aureus in the respiratory tract. Methods and Results:  The respiratory tract of nonimmunosuppressed and immunosuppressed Wistar rats were colonized with 4 × 105 viable cells of S. aureus K and then treated by administering 8192 arbitrary units (AU) nisin F intranasal. Symptoms of pneumonia were detected in the trachea and lungs of immunosuppressed rats that had not been treated with nisin F. The trachea and lungs of immunosuppressed rats treated with nisin F were healthy. No significant differences were recorded in blood cell indices. The antimicrobial activity of low concentrations nisin F (80–320 AU ml−1) was slightly stimulated by lysozyme and lactoferrin. Conclusions:  Nisin F inhibited the growth of S. aureus K in the respiratory tract of immunocompromised rats. Treatment with nisin F at 8192 AU proofed safe, as the trachea, lungs, bronchi and haematology of the rats appeared normal. Significance and Impact of the Study:  Nisin F is nontoxic and may be used to control respiratory tract infections caused by S. aureus. This is, however, a preliminary study with an animal model and need to be confirmed with studies on humans.