A procaryotic intracellular symbiont of the Great Salt Lake brine shrimp Artemia salina (L.).

Individuals of Artemia salina, the brine shrimp, were captured from the Great Salt Lake, a highly saline (330--340 g (see formula: solids content) terminal lake in Utah. Electron microscopy revealed the presence of intracellular procaryotic symbionts in the epithelial lining of the midgut. Fine structure and possible role of the symbiont are discussed.

The microbial ecology of the Great Salt Lake.

The Great Salt Lake is actually two lakes. A highly saline (330-gml(-1)) northern arm and a moderately saline (120-gml(-1)) southern arm separated by a semipermeable rock causeway. The lake, particularly the northern arm, has a massive accumulation of organic matter resulting from more than 100,000 years of productivity, cycling from a freshwater to a saline lake, plus the influence of human industry and agriculture in more recent times. The north arm planktonic and attached community consists principally of, in order of biomass: bacteria of at least two genera,Halobacterium andHalococcus; two algae,Dunaliella salina andD. viridis; the brine shrimp,Anemia salina; and, two species of brine fly,Ephydra gracilis andE. hians and possibly one more species. The algae and the bacteria appear to depend on each other for nutrients. The bacteria use organic matter produced by the algae and the algae use ammonia produced by the bacteria and possibly the brine shrimp. The production of ammonia appears to be the rate-limiting step although there is no shortage of other forms of nitrogen in the north arm. Based on aquarium studies, the potential for biomass production of algae and bacteria is much higher than actually observed in the north arm, leading to the postulation of two additional factors controlling population; the grazing of the algae by invertebrates with the excretion of compounds rich in nitrogen, and the effect of a low habitat temperature and winter cold on the bacteria, reducing their metabolic activities to nearly zero. Some aspects of the various organisms and their metabolism are discussed. A comparison is made with recent work on the Dead Sea.

Influence of phosphate compounds on certain fungi and their preservative effects on fresh cherry fruit (Prunus cerasus, L.).

Studies were conducted to ascertain the retarding effects of four phosphate compounds (sodium hexametaphosphate, sodium tripolyphosphate, sodium tetraphosphate, and tetrasodium pyrophosphate) on molding of fresh cherries (Prunus cerasus, L.). In vitro studies on their antimycotic effects against the most common fungal spoilers, Penicillium expansum, Rhizopus nigricans, and Botrytis sp., were also carried out. Sodium tetraphosphate appeared to be the most effective compound in preserving cherries and also had the greatest antimycotic effects in the in vitro studies. A 10% concentration, when applied as a dip, inhibited fungal growth on fresh cherries for up to 30 days of storage at 1.1 C (34 F) and a relative humidity of 94%, whereas untreated controls showed fungal growth at 14 days. Following in order of effectiveness were sodium hexametaphosphate, sodium tripolyphosphate, and tetrasodium pyrophosphate.

Simple medium for the selective isolation of Bacteroides and related organisms, and their occurrence in sewage.

A medium composed of 0.009% sodium azide, 0.07% sodium deoxycholate, and 0.0007% ethyl violet in Brain Heart Infusion Agar (Difco) and a process of incubation in an atmosphere of 90% N(2) and 10% CO(2) for the selective isolation of certain members of the intestinal bacteroides are described. The medium appears to select predominantly members of the genus Bacteroides and a few of the genus Sphaerophorus. A survey of the occurrence of these organisms in sewage and various stages of sewage treatment indicates that they survive complete sewage treatment in low numbers and that their rate of decline parallels that of the coliforms. Large numbers were recovered from sludge digestion tanks, suggesting a possible role in the anaerobic breakdown of organic matter.