Bacteria were isolated from soil on a 100-fold dilution of nutrient broth agar, a 10-fold dilution of alubumin yeast extract agar, or agar without additional nutrient. Their growth was severely suppressed by full strength nutrient broth but well supported by a 100-fold dilution of nutrient broth and these organisms were proposed to be called dilute nutrient broth (DNB) organisms. One percent each of peptone and meat extract, and 1% or 2% casamino acids severely suppressed growth of most of them. Glycine, arginine, serine, or lysine (10mM), yeast extract (0.1%), nicotinic acid or thiamine (20μg/ml), and sodium succinate (20-50mM) inhibited growth of many organisms though sensitivity of each organism to organic compounds was of a great variety. They were also highly sensitive to NaCl and KCl. Growth inhibition of some isolates by serine was recovered by coexisting threonine, alanine, or leucine and valine. Inhibitive effect of serine was also influenced by NaCl, KCl, CaCl2, or MgCl2.
Addition of lactate to the medium for the non-selective colony counts in sewage digestor fluids resulted in remarkable increase in the counts. In the presence of lactate, percentages of strictly anaerobic, Gram- negative curved rods in the isolates were usually much higher than those in the absence of lactate. Conversion of lactic acid to acetic acid by these bacteria was thought to be a very important process in the fermentation in digestor fluids. The lactate-utilizing bacteria were thought to belong to Desulfovibrio. Some strains of lactate-utilizing, strictly anaerobic, Gram-negative rods were also isolated.
Sulfate-reducers in sewage digestor fluids were enumerated by the anaerobic roll tube method. To discriminate them from other bacteria, two media, one of which contained 10% of the supernatant of autoclaved sewage digestor fluid and the other did not, were used. Enumeration of sulfate-reducers was easily carried out with these media by counting black colonies and isolation could also be performed by picking up the colonies without any particular attention. The addition of the sewage digestor fluid to the medium markedly increased the count of sulfate-reducers in the digestor fluid. They were proved to grow well in a richer medium, VLS-lactate agar, which contained Trypticase, yeast extract, 40% of the sewage digestor fluid, and so on. On the contrary, for sulfate-reducers in other environments such as polluted streams, the addition of sewage digestor fluid showed no effect.
Four kinds of cellulolytic strains of fungi were isolated for the purpose of cellulose biodegradation. Among them, Aspergillus sp. No. 81 could degrade more than 86% of Solka Floc added as the substrate within three days' cultivation. At the same time, the conversion rate to insoluble nitrogen from soluble nitrogen reached above 30% based on the initial amount of soluble nitrogen in liquid medium. From the values of insoluble nitrogen formed, the protein productivity by isolated Aspergillus sp. No. 81 was estimated to be 2-2.5g protein per 100g cellulose per day.
Protein-synthesizing activity at 0° of Pseudomonas aeruginosa, a mesophile, decreased by chilling at 0° and was lost completely after 12hr of the treatment. The relative amount of polysomes was not changed by chilling, and the addition of rifampin did not affect the dissociation of polysomes at 0°. These results suggest that the loss of viability by the chilling reported previously may be attributed to the cold sensitivity in an elongation-termination process of the protein synthesis. In Pseudomonas sp. strain 351 (P. 351), a psychrotroph, and Vibrio sp. strain ABE-1 (V. ABE-1), a psychrophile, protein-synthesizing activities at 0° were increased by chilling, but the polysome levels temporarily dropped by the chilling and recovered gradually to the original level.
When exponentially growing cells of Erwinia carotovora 645Ar, a sensitive strain to carotovoricin Er, were exposed to carotovoricin Er, turbidity of the culture decreased depending on the amount of bacteriocin added. Lysis by the bacteriocin infection occurred when the sensitive cells were treated with the bacteriocin in buffers containing phosphate, ethylenediaminetetraacetic acid, or arsenate, but did not occur in a buffer containing Mg2+. However, Mg2+ did not rescue the sensitive cells from lethal action of the bacteriocin. The lysis caused by the bacteriocin depended on temperature and the cells fixed with formaldehyde or glutaraldehyde did not lyse, suggesting that the lysis of carotovoricin-infected cells was caused by some lytic enzyme(s) of the sensitve cells rather than that of the bacteriocin itself.
Comparisons of proteins synthesized by the sexually differentiated and non-differentiated cells of Tremella mesenterica IFO-9313 (mating type ab) were performed with the soluble cell-fraction prepared by centrifugation at 25, 000×g for 30min. By employing the two-dimensional gel electrophoresis, it was demonstrated that alteration in synthesis of some cellular proteins is induced in response to a mating hormone, tremerogen A-10, secreted by T. mesenterica IFO-9310 (mating type AB). Typical example of alteration is as follows: Cellular proteins a (MW, 30, 000) and b (MW, 13, 000), located by a region of an isoelectric point, around 5.8, are remarkably decreased and increased, respectively, during sexual differentiation. These findings suggest the occurrence of gene control for sexual differentiation in response to the extracellular information substance.