An in vitro method using a multienzyme system for the estimation of protein digestibility has been developed. The multienzyme system consists of trypsin, chymotrypsin and peptidase. It was found that the pH of a protein suspension immediately after 10 min digestion with the multienzyme solution was highly correlated with the in vivo apparent digestibility of rats. Regression analyses of 23 samples tested showed that the correlation coefficient between pH at 10 min and in vivo apparent digestibility was 0.90 with a standard error of estimate of 2.23. The regression equation was Y = 210.464 -18.103, where "X" was the pH of protein suspension immediately after the 10 min digestion with the multienzyme solution. The most significant advantage of this in vitro method for predicting apparent protein digestibility was that it can be completed within 1 hr and with a high degree sensitivity. The method can detect the effects of trypsin inhibitor, chlorogenic acid, and heat treatment on protein digestibility. Strong buffer salts may affect the measurement of protein digestibility, but the buffering effects found in general food proteins and products tested did not create any problem with the procedure.

Swimming in ocean water, including ocean water at beaches not impacted by known point sources of pollution, is an increasing health concern. This study was an initial evaluation of the presence of indicator microbes and pathogens and the association among the indicator microbes, pathogens, and environmental conditions at a subtropical, recreational marine beach in south Florida impacted by non-point sources of pollution. Twelve water and eight sand samples were collected during four sampling events at high or low tide under elevated or reduced solar insolation conditions. The analyses performed included analyses of fecal indicator bacteria (FIB) (fecal coliforms, Escherichia coli, enterococci, and Clostridium perfringens), human-associated microbial source tracking (MST) markers (human polyomaviruses [HPyVs] and Enterococcus faecium esp gene), and pathogens (Vibrio vulnificus, Staphylococcus aureus, enterovirus, norovirus, hepatitis A virus, Cryptosporidium spp., and Giardia spp.). The enterococcus concentrations in water and sand determined by quantitative PCR were greater than the concentrations determined by membrane filtration measurement. The FIB concentrations in water were below the recreational water quality standards for three of the four sampling events, when pathogens and MST markers were also generally undetectable. The FIB levels exceeded regulatory guidelines during one event, and this was accompanied by detection of HPyVs and pathogens, including detection of the autochthonous bacterium V. vulnificus in sand and water, detection of the allochthonous protozoans Giardia spp. in water, and detection of Cryptosporidium spp. in sand samples. The elevated microbial levels were detected at high tide and under low-solar-insolation conditions. Additional sampling should be conducted to further explore the relationships between tidal and solar insolation conditions and between indicator microbes and pathogens in subtropical recreational marine waters impacted by non-point source pollution.Global estimates indicate that each year more than 120 million cases of gastrointestinal disease and 50 million cases of severe respiratory diseases are caused by swimming and bathing in wastewater-polluted coastal waters (42). Swimming-related illness is attributed predominantly to exposure to microbial pathogens, which enter the water through point sources, such as sewage outfalls. Water quality at beaches may also be impacted by non-point sources, such as storm water runoff, sand resuspension, animal fecal inputs, and human bather shedding (8,12,22,47,59).The concentration of indicator microorganisms in a body of recreational water is used to estimate the health risk to bathers. These microbes serve as surrogates for microbial pathogens. Studies show that the U.S. Environmental Protection Agency (EPA)-recommended indicator microbe for marine beaches, enterococci, shows a significant correlation with illness in marine beaches impacted by point source pollution (38,54). However, a similar correlation has not been identifi...

Enterococci, a common fecal indicator, and Staphylococcus aureus, a common skin pathogen, can be shed by bathers affecting the quality of recreational waters and resulting in possible human health impacts. Due to limited information available concerning human shedding of these microbes, this study focused on estimating the amounts of enterococci and S. aureus shed by bathers directly off their skin and indirectly via sand adhered to skin. Two sets of experiments were conducted at a marine beach located in Miami-Dade County, Florida. The first study, referred to as the "large pool" study, involved 10 volunteers who immersed their bodies in 4700 L during four 15 min cycles with exposure to beach sand in cycles 3 and 4. The "small pool" study involved 10 volunteers who were exposed to beach sand for 30 min before they individually entered a small tub. After each individual was rinsed with off-shore marine water, sand and rinse water were collected and analyzed for enterococci. Results from the "large pool" study showed that bathers shed concentrations of enterococci and S. aureus on the order of 6 × 10 5 and 6 × 10 6 colony forming units (CFU) per person in the first 15 min exposure period, respectively. Significant reductions in the bacteria shed per bather (50% reductions for S. aureus and 40% for enterococci) were observed in the subsequent bathing cycles. The "small pool" study results indicated that the enterococci contribution from sand adhered to skin was small (about 2% of the total) in comparison with the amount shed directly from the bodies of the volunteers. Results indicated that bathers transport significant amounts of enterococci and S. aureus to the water column, and thus human microbial bathing load should be considered as a nonpoint source when designing recreational water quality models.

BackgroundStaphylococcus aureus including methicillin resistant S. aureus, MRSA, are human colonizing bacteria that commonly cause opportunistic infections primarily involving the skin in otherwise healthy individuals. These infections have been linked to close contact and sharing of common facilities such as locker rooms, schools and prisons Waterborne exposure and transmission routes have not been traditionally associated with S. aureus infections. Coastal marine waters and beaches used for recreation are potential locations for the combination of high numbers of people with close contact and therefore could contribute to the exposure to and infection by these organisms. The primary aim of this study was to evaluate the amount and characteristics of the shedding of methicillin sensitive S. aureus, MSSA and MRSA by human bathers in marine waters.ResultsNasal cultures were collected from bathers, and water samples were collected from two sets of pools designed to isolate and quantify MSSA and MRSA shed by adults and toddlers during exposure to marine water. A combination of selective growth media and biochemical and polymerase chain reaction analysis was used to identify and perform limited characterization of the S. aureus isolated from the water and the participants. Twelve of 15 MRSA isolates collected from the water had identical genetic characteristics as the organisms isolated from the participants exposed to that water while the remaining 3 MRSA were without matching nasal isolates from participants. The amount of S. aureus shed per person corresponded to 105 to 106 CFU per person per 15-minute bathing period, with 15 to 20% of this quantity testing positive for MRSA.ConclusionsThis is the first report of a comparison of human colonizing organisms with bacteria from human exposed marine water attempting to confirm that participants shed their own colonizing MSSA and MRSA into their bathing milieu. These findings clearly demonstrate that adults and toddlers shed their colonizing organisms into marine waters and therefore can be sources of potentially pathogenic S. aureus and MRSA in recreational marine waters. Additional research is needed to evaluate recreational beaches and marine waters as potential exposure and transmission pathways for MRSA.