Tips from the Journals of the American Society for Microbiology

03/19/04

Fungi Cause of Wood Decay in Historic Antarctic Huts
Soft rot fungi appears to be the cause of some decay in historic wooden huts in Antarctic, say researchers from Minnesota, Iowa and New Zealand. Their results appear in the March 2004 issue of the journal Applied and Environmental Microbiology.

Three huts the Discovery hut, the Cape Royds hut and the Cape Evans hut --were built in Antarctica the early 20th century and were used to shelter men and equipment for several years during scientific investigations and explorations in the South Pole region. These huts, now international historic sites, have begun to exhibit wood degradation over the past several decades.

"It is a great misconception that the cold, dry polar climate protects organic material from decomposition and significant deterioration has occurred in the 90 to 100 years since the huts were built," say the researchers. "Nonbiological deterioration of wood from the huts and artifacts caused by salt corrosion has resulted in significant damage. Microbial degradation of wood at these historic sites may also occur, but nothing is known about the organisms responsible."

In the study, samples of wood were taken from three expedition huts built between 1901 and 1911 and transported to Antarctica. Several species of Cadophora fungi were identified in two of the three samples and researchers determined the cause to be moisture in the ground from extreme melting and thawing during certain seasons.

"The presence of Cadophora species, but only limited decay, suggests there is no immediate threat to structural integrity of the huts," say the researchers. "These fungi, however, are widely found in wood from the historic huts and have the capacity to cause extensive soft rot if conditions that are more conducive to decay become common."

(R.A. Blanchette, B.W. Held, J.A. Jurgens, D.L. McNew, T.C. Harrington, S.M. Duncan, R.L. Farrell. 2004. Wood-destroying soft rot fungi in the historic expedition huts of Antarctica. Applied and Environmental Microbiology, 70. 3: 1328-1335.)

Cheese-Making Bacteria Survive Pasteurization
The bacteria involved in the ripening of cheeses may find their way into the final product by surviving the pasteurization process say researchers from Italy, Ireland and France. Their findings appear in the March 2004 issue of the journal Applied and Environmental Microbiology.

In the study researchers looked at strains of Lactobacillus plantarum, one of a group of bacteria known as nonstarter lactic acid bacteria (NSLAB) believed to be essential to the ripening process and flavor development in a variety of cheeses including cheddar, feta and pecorino. They found that while heat treatment, like that used in pasteurization, killed most of the bacteria, some did recover.

"Since more hygienic cheese-making practices have negligible effects on NSLAB contamination, survival during pasteurization is the most probably entry route for the few NSLAB cells found in cheese during early ripening," say the researchers, who also tried to identify the mechanisms of heat resistance. "The results of this study show that the heat resistance of L. plantarum is a complex process which is also related to cold shock and general stress responses."

(M. De Angelis, R. Di Cagno, C. Huet, C. Crecchio, P.F. Fox, M. Gobbetti. 2004. Heat shock response in Lactobacillus plantarum. Applied and Environmental Microbiology, 70. 3: 1336-1346.)

Sand Fly Saliva Contributes to Disease in Humans
Researchers from Texas and California found that the saliva of female sand flies may be a contributing factor in a disease they transmit to humans. Their findings appear in the March 2004 issue of the journal Infection and Immunity.

Leishmania amazonensis, considered endemic in South America and other parts of the world, is a parasite that causes lesions often resulting in disfigurement and sometimes death. In the study, mice were administered injections of salivary gland extracts from sand flies combined with L. amazonensis. Those mice developed earlier onset of disease, larger lesions, and higher levels of interleukin-10 (IL-10) compared to mice that did not receive the extracts. Although the role of IL-10 in the progression of the disease is uncertain, it is thought to inhibit the destruction of the infectious organism.

"Together, these results imply that the sand fly saliva facilitates Leishmania evasion of the host immune system by modulating IL-10 production," say the researchers. "These observations are important in our understanding of the pathogenic mechanisms of cutaneous leishmanias caused by this New World parasite species."

(N.B. Norsworthy, J. Sun, D. Elnaiem, G. Lanzaro, L. Soong. 2004. Sand fly saliva enhances Leishmania amazonensis infection by modulating interleukin-10 production. Infection and Immunity, 72. 3: 1240-1247.)

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