A two-layer membrane filtration (MF) medium (injury-mitigating MF [IM-MF]) and a procedure for the enumeration of injured fecal coliforms are described. These procedures included the addition of glycerol and acetate plus reducing agents to both layers of a two-layer medium and rinsing of the filter with a rich resuscitation medium. Some changes in incubation time and temperatures were used. This method was compared with the multiple-tube fermentation most-probable-number procedure and the one-step M-FC agar-membrane filter method (direct M-FC) in terms of fecal coliform recovery from various aquatic environments that cause bacterial injury. With chlorinated sewage effluents, results of the IM-MF technique were equal to or greater than the most probable number in 9 of 18 trials and were 1.3 to 19 times greater than the M-FC method. When sewage samples were chlorinated in the laboratory, fecal coliform counts with IM-MF equaled or exceeded the most probable number in 7 of 15 trials and always exceeded the M-FC. M-FC was exceeded by IM-MF in 30 of 33 trials with clean mountain stream water. Fecal coliform bacteria that were exposed to low levels of an iodophore in the laboratory produced IM-MF counts 3 to 10 times greater than those with M-FC. A biochemical rationale for the formation of the IM-MF medium is discussed.

Bacterial survival was determined in linens (i) inoculated with Staphylococcus aureus (ii), taken from hospital isolation patients' beds, and (iii) used by students in their homes. Two different washers using temperatures of 38, 49, 54 and 60 C, respectively, for different times were employed along with a commercial tumbler dryer. Findings, after macerating the linens in a Waring blender and enumerating on nonselective media, indicate that acceptable levels of survivors can be achieved in motel and hotel linens by an 8to 10-min wash cycle at 54 C followed by adequate drying. However, it is recommended that a wash cycle with 60 C for 10 to 13 min be employed for linens in health care factilities. The microbial significance of various laundering practices is discussed.

Fecal colitbrm (FC) disappearance studies were conducted in Ford Lake during the summer of 1979. Ford Lake, an artificial impoundment at the lower end of the Huron River drainage basin belov, ~ Ypsilanti, Michigan, receives all upstream flow (2072 km: of drainage). During dry weather an overall daytime FC disappearance rate of 0.4 (h-t) (K base e) was measured using dye tracer for timed collection. assuming a first order equation of the Chick type. Sedimentation was demonstrated as important in the overall FC disappearance in the upper end of the lake. Rooftop studies showed light level to affect daytime disappearance. Two types of wet weather conditions were documented: (1) where a substantial increase in flow occurred due to an isolated upriver storm; and (2) as a result of two different storm events in the Ford Lake area itself. In both cases, Ford Lake was effective in substantially reducing the large FC contribution.

Comparisons of two common bioaerosol samplers were made after sampling and enumeration of airborne fungal propagules in several office structures on a university campus in Southern California. Data collected on five occasions throughout the year showed that a Surface Air Systems (SAS) high flow portable sampler recovered consistently lower levels of colony forming units (cfu) than an Andersen N6 single stage impactor. There was no difference statistically between the samplers when concentrations of Cladosporium were compared. Compared to the Andersen N6, the SAS sampler recovered about half the number of cfu for three other fungal categories, i.e. non-sporulating species, Aspergillus and Penicillium and others. Differences in sampler efficiencies are discussed in terms of effective particle diameters. Counts of culturable airborne fungal spores obtained with the SAS sampler should be interpreted with caution when genera other than Cladosporium predominate.

Two methods are described for measurement of bacterial injury in water. Laboratory time preceding cell division measured with slide cultures and spheroplast formation after lysozyme treatment were accurate and rapid measurements of bacterial damage.