scholarly journals First Report of Natural Hybrids of Phytophthora nicotianae and P. cactorum on Loquat in Taiwan

Plant Disease ◽  
2001 ◽  
Vol 85 (1) ◽  
pp. 98-98 ◽  
Author(s):  
W. A. Man in 't Veld
Keyword(s):  
Growth Temperature ◽  
Petri Dish ◽  
Maximum Growth ◽  
Selective Medium ◽  
Phytophthora Nicotianae ◽  
Eriobotrya Japonica ◽  
Maximum Growth Temperature ◽  
Natural Hybrids ◽  
Central Taiwan ◽  
Species Specific

In 1995 loquat trees (Eriobotrya japonica [Thunb.] Lindl.) in several orchards in central Taiwan suffered from a severe stemrot and rootrot (2). Two populations of Phytophthora spp. isolates were recovered from diseased trees by placing pieces of plant tissue in a petri dish containing selective medium (2). One group of isolates possessed papillate sporangia, appeared to be heterothallic with amphigynous antheridia, and had a maximum growth temperature of 36°C. Upon mating, isolates of this group produced oogonia and oospores measuring 26.1 and 21.4 μm in diameter, respectively. These isolates were identified as typical strains of P. parasitica (=P. nicotianae) (2). The second group of isolates showed papillate sporangia, was homothallic with predominantly amphigynous antheridia, and had a maximum growth temperature of 34.5°C. However, the sizes of oogonia and oospores were considerably larger (average 34.7 and 30.3 μm in diameter, respectively) than those of P. nicotianae. Amplification of genomic DNA of one isolate (95023) of the second group by polymerase chain reaction (PCR) using P. nicotianae species specific primers PAR1 and PAR2, produced a special 1,000 bp sequence, indicating that the atypical isolates of second group were closely related to P. nicotianae. Isozyme analysis of two isolates (95023 and 95034, provided by L. L. Chern, Taiwan) of the second group, using the dimeric enzymes malic enzyme (MDHP; EC 1.1.1.40) and malate dehydrogenase (MDH; EC 1.1.1.37), was applied as described before (1,3). These two isolates generated the same three banded patterns using either enzyme (genotype: MDHP: 92/100; MDH-2: 93/100); the Mdhp92 allele and the Mdh-293 allele are diagnostic for P. cactorum, whereas the Mdhp100 allele and the Mdh-2100 allele are diagnostic for P. nicotianae. These well-defined heterozygous band patterns were exactly identical to those generated in atypical isolates which were identified earlier as hybrids of P. nicotianae and P. cactorum (1,3). Based on their atypical morphology and isozyme genotyping, it was concluded that these two isolates of the second group represent hybrids of P. nicotianae and P. cactorum. One of the parents, P. nicotianae, was also found closely associated with diseased loquat trees; the other parental species, P. cactorum, was not isolated from loquat in this study. It is the first time that natural hybrids of P. nicotianae and P. cactorum were found on loquat in Asia. References: (1) P. J. M. Bonants et al. Phytopathology 90:867–874, 2000. (2) L. L. Chern et al. Plant Dis. 82:651–656, 1998. (3) W. A. Man in 't Veld et al. Phytopathology 88:922–929, 1998.

Mesophilic mutants of an obligate psychrophile, Micrococcus cryophilus

1969 ◽  
Vol 15 (10) ◽  
pp. 1145-1150 ◽  
Author(s):  
P-C. Tai ◽  
H. Jackson
Keyword(s):  
Growth Temperature ◽  
Metabolic Pathways ◽  
Thermal Denaturation ◽  
Deoxyribonucleic Acid ◽  
Elevated Temperatures ◽  
Maximum Growth ◽  
Maximal Growth ◽  
Denaturation Temperature ◽  
Maximum Growth Temperature ◽  
Thermal Denaturation Temperature

Several mutants with elevated maximal growth temperature (MGT) were developed from an obligate psychrophile, Micrococcus cryophilus ATCC 15174, by ultraviolet irradiation. Two of the mutants, T8 and M19, have the most similar characteristics to those of their parent. The mutants lost the ability to grow well at 0 °C and showed changes in metabolic pathways while acquiring the ability to grow at elevated temperatures. Heat resistance and deoxyribonucleic acid thermal denaturation temperature were shown to be unrelated to maximum growth temperature. The significance of the mutants is discussed.

scholarly journals Growth Temperatures of Ropy Slime-Producing Lactic Acid Bacteria

1990 ◽  
Vol 53 (9) ◽  
pp. 793-794 ◽  
Author(s):  
HANNU J. KORKEALA ◽  
PIA M. MÄKELÄ ◽  
HANNU L. SUOMINEN
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Growth Temperature ◽  
Meat Products ◽  
Maximum Growth ◽  
Meat Processing ◽  
Continuous Growth ◽  
Maximum Growth Temperature ◽  
Processing Plants ◽  
Cooked Meat

The minimum, optimum, and maximum growth temperatures of ropy slime-producing lactic acid bacteria able to spoil vacuum-packed cooked meat products were determined on MRS-agar with temperature-gradient incubator GradiplateR W10. The minimum growth temperatures of slime-producing lactobacilli and Leuconostoc mesenteroides strain D1 were below −1°C and 4°C, respectively. The low minimum growth temperature allows these bacteria to compete with other bacteria in meat processing plants and in meat products causing ropiness problems. The maximum growth temperatures varied between 36.6–39.8°C. The maximum growth temperature of lactobacilli seemed to be an unstable character. Single lactobacilli colonies were able to grow above the actual maximum growth temperature, which is determined as the edge of continuous growth of the bacteria. The significance of this phenomenon needs further study.

scholarly journals Ion permeability of the cytoplasmic membrane limits the maximum growth temperature of bacteria and archaea

1995 ◽  
Vol 18 (5) ◽  
pp. 925-932 ◽  
Author(s):  
Jack L.C.M. van de Vossenberg ◽  
Trees Ubbink-Kok ◽  
Marieke G.L. Elferink ◽  
Arnold J.M. Driessen ◽  
Wil N. Konings
Keyword(s):  
Growth Temperature ◽  
Cytoplasmic Membrane ◽  
Maximum Growth ◽  
Ion Permeability ◽  
Maximum Growth Temperature

EFFECTS OF INCUBATION TEMPERATURE ON THE SALT TOLERANCE OF SALMONELLA

1972 ◽  
Vol 35 (1) ◽  
pp. 39-44 ◽  
Author(s):  
Jack R. Matches ◽  
J. Liston
Keyword(s):  
Salt Tolerance ◽  
Salmonella Typhimurium ◽  
Growth Temperature ◽  
Low Temperatures ◽  
Incubation Temperature ◽  
Maximum Growth ◽  
Nutrient Broth ◽  
Maximum Growth Temperature ◽  
Low Levels ◽  
Salmonella Heidelberg

Salt has been shown effective in preventing growth of salmonellae in foods. Many of the studies reported in the literature have been on the lethal action of high levels of salt as used in curing brines. Little information is available on the interaction of incubation temperature and low levels of salt on the growth of salmonellae. The growth of Salmonella heidelberg, Salmonella typhimurium, and Salmonella derby in nutrient broth containing 0 to 8% added NaCl (in 0.5 or 1% increments) has been tested by shake cultures at 8, 12, 22, and 37 C. In addition, S. heidelberg has also been tested in 0 to 9% added NaCl at 39, 41, 43, and 45 C. At 8 C, growth of S. heidelberg took place in 1 and 2% added NaCl; S. typhimurium increased in numbers in 1% added NaCl; and S. derby failed to increase. When incubated at 12 C, the three serotypes were all able to increase in numbers in the range of 0 to 4% NaCl. At 22 C, this range increased from 0 to a maximum of 5 to 8%. When incubated at 37 C, the organisms were able to increase in numbers in up to 7 to 8% NaCl. The salinity of the medium was not found to increase the maximum growth temperature of S. heidelberg as has been reported in the literature for other organisms. Low levels of salt were found to stimulate growth of salmonellae. This stimulation was more pronounced at low temperatures than near the optimum for the organisms. Since salt is used to preserve foods, these data are important in the preservation of perishable foods. Salt concentrations preventing growth of salmonellae at low temperatures may not be sufficient to prevent growth of these pathogens at higher temperatures.

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