- Volume 78, Issue 1, 1973

Summary: Streptococcus faecalis 10C1 and 6783 grew anaerobically on glucose in media lacking lipoic acid and acetate, and assays with Streptococcus cremoris KH indicated that extracts of S. faecalis 10C1 contained lipoic acid activity equivalent to 200 ng of α-d,l-lipoic acid/mg protein. The Y glucose value for a continuous culture of strain 10C1 grown anaerobically in lipoic acid-deficient medium was 37·2, about the same as that for 10C1 in lipoic acid-sufficient medium (35·5). Strains 10C1 and 6783 metabolized low concentrations of glucose (1 to 8 mümol/ml) non-homolactically and produced per mol of glucose about 1·0 mol lactate, 1·2 mol acetate, and 0·4 mol ethanol. Appreciable amounts of pyruvate, formate, glycerol, acetoin, diacetyl, and 2,3-butylene glycol were not detected. The Y glucose values for strain 10C1 were lower (25, 17 and 21, respectively) if 10−4 M-arsenite or 0·5 % acetate was added or the pH value in the fermentor was decreased to 5·3. With acetate added or the pH value reduced, the glucose was metabolized mostly to lactate. Results indicate that S. faecalis 10C1 used the pyruvate-dehydrogenase-enzyme complex rather than the phosphoroclastic mechanism in metabolizing anaerobically to acetate approximately half of the pyruvate produced from low concentrations of glucose.

Summary: Snoswell’s (1959) postulate that NAD-independent lactic dehydrogenases are associated with anaerobiosis has been examined by searching for the enzymes in 20 heterotrophic bacteria. The NAD-independent dehydrogenases are widely distributed but are particularly associated with facultative anaerobes.

Summary: The NAD-dependent lactate dehydrogenase of Rhizopus oryzae, like some bacterial lactate dehydrogenases, catalyses reduction of pyruvate by NADH but not the reverse reaction. It will, however, catalyse reduction of the NAD+ analogue, 3-acetylpyridine adenine dinucleotide (APAD+) by l(+)-lactate; NAD+ does not inhibit the rate of APAD+ reduction in this reaction. The relationship between pyruvate reductase activity and NADH concentration is sigmoidal with a high apparent K m for NADH (2·9 × 10−4 M).

Enzyme level reaches a peak during early vegetative growth of the mycelium and declines rapidly before sporulation. The peak level reached is dependent on the glucose concentration of the medium, being greatest in high glucose media. When grown in media containing growth-limiting concentrations of glucose, lactate dehydrogenase activity is negligible. Transfer of such mycelia to high glucose media results in a rapid increase in the specific activity of the enzyme; this increase is prevented by cycloheximide. High levels of lactate dehydrogenase can also be induced by growing the fungus in media containing growth-limiting concentrations of zinc.

Summary: Ninety-six Campylobacters were isolated from cattle, sheep, pigs and fowls, of which 40 were studied in detail. Characterization by routine biochemical tests indicated that all isolates were similar and that differences did not correspond with habitat or pathogenicity. The electrophoresis patterns of acid plus phenol-soluble proteins from the 40 Campylobacters allowed the isolates to be placed in three groups which correlated with habitat. Group I comprised all the Campylobacters from the bovine genital tract (these isolates were associated with infertility). Group II comprised all the strains isolated from cattle faeces and all the strains associated with sporadic abortions in cattle and sheep. Group III comprised all the Campylobacters from healthy pigs and from pigs with swine dysentery. Isolates could not be differentiated by electrophoresis of total soluble proteins. Isocitrate dehydrogenase and peroxidase electrophoresis patterns each allowed the pig Campylobacters to be differentiated from cattle and sheep Campylobacters, but did not allow finer differentiation. Malate dehydrogenase patterns, which were produced only by the pig Campylobacters, provided three groups but these did not correlate with isolation source. It is concluded that there is no qualitative difference in the Campylobacter population of the gut of healthy and dysenteric pigs.

Summary: The survival of Nocardia corallina and the degradation of constituents were examined during periods of starvation. Organisms were harvested at the end of the growth phase and were starved, after resuspending in phosphate buffer containing Mg2+, with vigorous aeration at 30°C. Viability fell gradually to 50 % over a period of 480 h. After 48 h of starvation the dry weight of the organisms was reduced by 35% and the Q O2, was decreased from 10 to approximately 1. The fall in dry weight coincided with a decrease of microbial polysaccharide from 25 % to 7 % of the initial dry weight. After this degradation of polysaccharide there was a decrease in microbial protein and a release of ammonia into the supernatant. The contribution of different constituents to the total decrease in dry weight during a period of 240 h starvation was; polysaccharide, 40 %; protein, 25 %; RNA, 6%; total fatty acids, 5%. Loss of viability could not be directly correlated with the utilization of any particular constituent.

Summary: A temperature-sensitive Bacillus subtilis mutant (Combts M8) has been isolated which is defective in genetic transformation at the restrictive temperature (42 °C). The mutant was selected on the basis of its transforming properties at 42 and 28 °C on agar plates spread with DNA. During growth at 37 °C the mutant shows normal development of transformability (competence), whereas at 42 °C competence is very low or completely absent. At 42 °C the mutant is not transfectable with DNA from bacteriophage 029, but susceptible to normal infection with the complete bacteriophage, indicating that the ability to take up exogenous DNA is impaired at this temperature.

In addition to the loss of competence the mutant shows a changed growth pattern at the restrictive temperature: cultures grow initially at the same rate as cultures of the parental strain up to the late exponential phase of growth and then abruptly change over to a much lower growth rate, simultaneously producing shorter cells than the parental strain. From a genetic analysis evidence has been obtained suggesting that the two altered properties of the mutant, loss of competence and a changed growth pattern at 42 °C, are due to the same mutation.

When the mutant is shifted during growth from the restrictive to the permissive temperature, its subsequent pattern of competence development is similar to that displayed by the parental strain after such a shift. Likewise, the response to an opposite shift is also similar in both strains. Only when the mutant is grown continuously at 42 °C, including the overnight incubation period, is the mutant genotype expressed completely.

The results suggest that at 42 °C the mutant is blocked in a relatively late step in the development of competence.

Summary: Non-transferring plasmids containing the genetic determinants for resistance to streptomycin (Sm), sulphonamides (Su) and ampicillin (Ap), colicine production (Col) and α-haemolysin production (Hly) were incorporated in the same strain of Escherichia coli K12. A plasmid coding for tetracycline (Tc) resistance was then co-transferred to it by eleven transfer factors, including F and I.

Some of the transfer factors differed greatly in the rate at which they transferred the determinants from this Tc+Col+Hly+Sm+Su+Ap+ donor strain to another strain of K12 and some of the determinants differed greatly in the rate at which they were transferred. Only F and one other transfer factor were found to transmit Hly. Some transfer factors were not detected to transfer Col or Ap. Linkage was demonstrated between Tc and three transfer factors, including F, and between Sm and Su. The other plasmids and transfer factors appeared to exist as separate units. In mating studies between the donor strain possessing both F and I, and recipient strains possessing different combinations of these transfer factors, the determinants most greatly affected by the choice of recipient were the F-linked Tc and Hly.

When a multiple antibiotic resistance plasmid, instead of the Tc one, was co-transferred to the donor strain by I or F, then I, but not F, established a linkage with this plasmid. Although this linkage was probably responsible for the higher rate at which the plasmid was transferred from the I+ than from the F+ strain, its actual transfer rate was lower than that of the unlinked Col plasmid also possessed by the I+ strain.

Summary: Crosses between P+ strains of Vibrio cholerae (biotype ‘eltor’) and P− strains of V. cholerae (‘classical’) were infertile under conditions in which P+ × P− crosses of V. cholerae (‘classical’) strains were fertile. The efficiency of conjugation, as determined by the frequency of P transfer, was lower with P+ strains of the ‘eltor’ biotype compared with P+ strains of V. cholerae (‘classical’). However, incubation of P+ strains at 44·5°C, prior to mating, induced fertility in bacteria of the ‘eltor’ biotype and enhanced it in V. cholerae (‘classical’) crosses. It is suggested that new donors associated with a greater efficiency of conjugation are formed at 44·5°C in P+ strains of both biotypes.

Summary: Botrytis cinerea conidia failed to germinate whilst being leached with water or mineral solution. Only a small proportion of conidia germinated in water after cessation of leaching but a high proportion germinated in the presence of glucose or mineral/glucose solutions. Sometimes minerals alone could restore germmation of leached conidia. Conidia germinated well on membranes during leaching with glucose or mineral/glucose solutions.

The majority of isolates of bacteria obtained from leaves were positive or strongly positive in aniline blue dye-absorption tests, indicating the presence of extracellular polysaccharide. Uptake of nutrients into the polysaccharide sheath of bacteria situated near conidia may increase the concentration gradient from within to outside the conidium, so resulting in nutrient depletion and loss of germinability. The effect brought about by leaching of conidia was thought to simulate the action of bacteria. Similarities with spores inhibited in soil by fungistasis are discussed.

Summary: During the growth of the yeast-like fungus Pullularia pullulans, the pattern of glucose utilization by the cell varied from a complete inability to elaborate extracellular polysaccharide to the diversion of almost two-thirds of metabolized glucose to pullulan elaboration. The effects of carbon and nitrogen levels on this changing pattern during growth were examined. These investigations indicated that the elaboration of pullulan, and the onset of a morphological change of Pullularia from a filamentous to a yeast-like form, were related to the availability of nitrogen, and not carbon, in the growth medium.

Summary: Aeromonas hydrophila strain B3646 produced extracellular haemolysin in various complex or defined liquid media. The haemolytic activity in all media investigated was proportional to the bacterial dry weight at the end of exponential growth, and there is probably no way to stimulate the production of haemolysin specifically. The haemolytic activity appeared late in the autolytic part of the stationary phase. Inhibition of protein and DNA synthesis by chloramphenicol or nalidixic acid revealed that the haemolysin was synthesized during the late logarithmic phase and released into the medium by lysis. Attempts to release the haemolysin from the bacteria by various disintegration methods were all negative. Cyclic AMP did not affect the synthesis or release of haemolytic activity. The haemolysin is probably bound to some bacterial constituent in the cytoplasm and activated upon lysis. Malate dehydrogenase and protease activity accumulated in the medium simultaneously during this lytic phase, while staphylolytic enzyme was released during the logarithmic phase.

Summary: Zoospores of Phytophthora palmivora suspended in water aggregated within 2 min at 16°C. Individual spores in aggregates were separate and actively swimming. The optimum temperature for aggregation was 16°C. Aggregate formation depended on zoospore concentration and depth of suspension.

Summary: A study has been made in methanol- and ethanol-grown Hyphomicrobium x of the specific activities of the following enzymes: serine hydroxymethyltransferase, serine-glyoxylate aminotransferase, hydroxypyruvate reductase, glycerate kinase, phosphopyruvate hydratase, phosphopyruvate carboxylase, serine dehydratase, malate dehydrogenase (decarboxylating), phosphopyruvate synthase, phosphopyruvate carboxykinase, glycerate phosphomutase, malate dehydrogenase, malate lyase (CoA acetylating-ATP cleaving), citrate synthase, aconitate hydratase, isocitrate lyase and malate synthase. It was concluded that during growth on ethanol the glyoxylate cycle operated, while during growth on methanol, C1 units and glyoxylate were converted to malate by the serine pathway. The glyoxylate was regenerated by cleavage of malate into glyoxylate and acetyl-CoA. The acetyl-CoA was itself oxidized to glyoxylate by some of the reactions of the tricarboxylic acid cycle and isocitrate lyase, thus permitting net synthesis of C3 and C4 compounds from methanol and carbon dioxide.

Summary: The effects of l-sorbose on the diameter, compartment length, wall thickness and fine structure of hyphae from colonies and batch cultures of Neurospora crassa (spco 1 and spco 9) were studied. The specific growth rates and yields of the strains in batch culture and their germ-tube specific growth rates were at most reduced by only 18% when 2% l-sorbose was added to Vogel’s medium containing 1% sucrose.

The addition of l-sorbose to solid medium induced both strains to branch profusely and resulted in the formation of dense, slow growing colonies (about 90 % reduction in radial growth rate). This reduction in the radial growth rate of spco 9 colonies could be largely correlated with a reduction (from 4·0 mm to 0·5 mm) in the width of the peripheral growth zone of colonies grown on media containing l-sorbose. Plugging of the septal pores and autolysis of hyphae of spco 9 occurred closer to the colony’s periphery when l-sorbose was present in the medium. l-Sorbose reduced the number and size of the vesicles found at the tips of hyphae of spco 9.