This study reports the capacity of Staphylococcus aureus strain 7-8 to undergo photoenzymatic repair of UV-irradiation induced damage and compares it to the photoreactivation (PR) response of Escherichia coli strain B. Staphylococcus aureus showed greater inhibition by UV irradiation than E. coli, consistent with its higher adenine and thymine content of DNA. Staphylococcus aureus showed an enhanced rate of photoreactivation with no lag in initiation of the PR response at low PR doses compared to E. coli. Maximum PR capacity of both cultures was about equal and occurred in cultures incubated at 23-25°. The PR responses at 11-12 and 35-37° for S. aureus and E. coli differed although both were capable of PR at each of these temperatures. The PR response of E. coli was directly related to the dosage of PR light (J/m2); however, the photoenzymatic capacity of S. aureus was not directly responsive to continued decrease in light intensity. The capacity of S. aureus to undergo liquid holding recovery (LHR) occurred at 23-25° (not at 11-12° or 35-37°), whereas E. coli underwent LHR at 11-12° and 23-25° but not at 35-37°. The LHR response of S. aureus was somewhat more effective than E. coli and did not show the direct response to increased liquid-holding period as did E. coli.
The soil cores of a salt tolerant grass Diplachne fusca Linn. Beauv. Commonly grown in the saline-sodic area of Pakistan showed high nitrogenase activity. High input values of N, up to 127 kg/ha/100 days were obtained by extrapolating the acetylene reduction values. Anabaenavariabilis was isolated from the soil, and isolated algae showed values of nitrogenase activity and 15N incorporation comparable to those of A. cylindrica. Enrichment assays resulted in recovery of several N2-fixing bacteria. Some characteristics of the most efficient isolate were studied, which suggests that the isolate belongs to genus Azospirillum. However, confirmative identification with the collaboration of the German Collection of Microorganisms, Gottingen, is in progress.
The relationship of nine Candida species, five Torulopsis species, and five species and two varieties of Kloeckera to the ascosporogenous yeast species considered to be their teleomorphs was studied by electrophoretic comparison of enzymes. Close relationships were seen between fourteen teleomorphs and their anamorphic counterparts, Candida guilliermondii and Pichia guilliermondii, Candida krusei and Issatchenkia orientalis (Pichia kudriavzevii), Candida lambica and Pichia fermentans, Candidamelinii and Hansenula wingei, Candida utilis and Hansenula jadinii, Candida macedoniensis and Kluyveromyces marxianus, Candida pseudotropicalis and Kluyveromyces fragilis, Candida parapsilosis (group 2) and Lodderomyces elongisporus, Torulopsis holmii and Saccharomyces exiguus, Torulopsis colliculosa and Torulaspora delbrueckii (Saccharomycesfermentati), Torulopsis stellata and Torulaspora delbrueckii (Saccharomycesrosei), Kloeckera africana and Hanseniaspora vinea, Kloeckeraapiculata and Hanseniaspora uvarum, and Kloeckera japonica and Hanseniaspora valbyensis. There was no apparent relation between the four pairs: Candida valida and Pichia membranaefaciens, Candida parapsilosis (group 1) and Lodderomyces elongisporus, Torulopsis molischiana and Hansenula capculata, and Torulopsis candida and Debaryomyceshansenii and Debaryomyces marama. From these results, this zymographic technique is considered to be a useful tool for the study of relalationships between the different states of a yeast species.
Species composition and growth-temperature characteristics of coliforms isolated from several types of environmental samples were investigated. It was possible to divide these isolates into eight distinct groups, six species groups and two unidentified, on the basis of their biochemical properties. The isolates included in the unidentified groups, giving IMViC reactions of --++ and -+-+, were tentatively termed "typical psychrotrophic coliform (TPC)" bacteria because of their ability to grow at 1°. The TPC bacteria and Citrobacter freundii constituted the normal coliform flora of mountain soil and stream water samples. In contrast, Escherichia coli and Klebsiella pneumoniae were major predominant coliforms in polluted river water and sewage samples, the former being most common in human feces samples. In testing the growth response at different temperatures, the isolates of E. coli and the TPC bacteria showed relatively constant temperature preferences regardless of origin, whereas those of other coliform members gave varied results dependent upon their sources. The results provided circumstantial evidence that population densities of coliforms able to grow in EC broth at 43° and above but not in ordinary nutrient broth at 5° within 7 days of incubation in the environment are directly proportional to the degree of potential fecal contamination.
Four strains, representative of an undescribed species of Pichia, have been recovered from insect infestations of Euphorbia ingens in South Africa. A description of the new species, Pichia kodamae, is given. The type strain of Pichia kodamae was found not to hybridize with strains of Pichia pini, Pichia methanolica and Pichia cellobiosa.
Although Serratia marcescens has been reported to possess pili, little attention has been given to the role of the pill in this organism. This piliated bacterium agglutinates human and chicken erythrocytes, and the activity is inhibited by α-D-mannose. The degree of piliation, induced by shaking or static culture conditions, correlate with the hemagglutination activity. S. marcescens depiliated by UV irradiation failed to agglutinate erythrocytes. The possible role of pili as an important virulence factor in promoting adherence to host cells was studied by investigating the ability of piliated S. marcescens to attach to buccal epithelial cells. Results showed that S. marcescens attached to human buccal epithelial cells and that adherence is associated with the presence of common type-1 pili on their surfaces.
The growth kinetics of NH4+-oxidizing bacteria and NO2--oxidizing bacteria were studied using the indirect immunofluorescent counting method. In the case of NH4+-oxidizing bacteria, the maximum specific growth rate (μmax) was 0.58 day-1 and the half saturation constant (Kg) was 200μM NH4+. Maximum specific activity (Amax) during the exponential growth phase was 6.6×10-5nmol/cell/day. From the relationship between the specific growth rate and the specific activity, the maximum growth yield (Ymax) and maintenance coefficient (m) were calculated. Ymax was 1.0×104cells/nmol NH4+ and m was 1.1×10-5 nmol/cell/day. The maintenance coefficient was about 17% of Amax. In the case of NO2--oxidizing bacteria, μmax, Kg and Amax were 0.81 Day-1, 15μM and 2.8×10-4nmol/cell/day, respectively. Ymax and m could not be calculated, since the maintenance coefficient became negative. From these results, the growth kinetics of nitrifying bacteria were discussed.
The growth of NH4+-oxidizing bacteria and NO2--oxidizing bacteria and the concentration of NO2- were measured in mixed culture systems. The growth kinetics of the above two nitrifying bacteria in the mixed cultures were as same as those in the uni-bacterial cultures (described previously). When the NO2- concentration was maintained at a constant level, the growth yields of NH4+- and NO2--oxidizing bacteria were in the ratio of about 2:1. The specific activities of NO2--oxidizing bacteria, calculated from the data of the uni-bacterial cultures and the mixed cultures, did not change linearly with the specific growth rates. It was suggested that energy spilling might occur at higher specific growth rates. The conditions under which the NO2- concentration may be maintained at a constant level were discussed.