Section 3 — Molecular and Microbial Genetics 



it was possible to demonstrate transduction of 

 sporogenesis in an asporogenous strain (Sp~l) 

 of Bacillus subtitisM) It was also reported that 

 the locus sp-1 was linked to prototrophy and to 

 streptomycin and erythromycin resistance loci 

 at different frequencies. Examination of sporo- 

 genous (sp + ) recombinants obtained from a 

 number of other asporogenous (sp~) strains by 

 transduction with SB19-ery (prot, sp + , str-r and 

 ery-r) as donor, revealed that three distinct sp 

 loci were linked to amino acid markers (serine, 

 phenylalanine and tryptophan-phenylalanine) 

 at relatively high frequencies. By reciprocal 

 transduction performed with fourteen sp~ 

 strains, nine genes which govern spore formation 

 in this organism were recognizable. The finding 

 that certain sp loci are linked to amino acid 

 markers or to antibiotic markers and the re- 

 sults of the reciprocal transduction experiments 

 suggest that these sp~ characters are under the 

 control of chromosomal determinants. In addi- 

 tion, an anomalous recombination pattern was 

 observed with strain Sp _ H12-3. This strain was 

 never transduced to sp + even when a wild type 

 donor was used, although this strain could act 

 effectively as donor for other sp' strains and was 

 transducible for prototrophy and erythromycin 

 resistance. The mechanism responsible for this 

 anomalous recombination will be discusesd. 



18th hour the growth stops and in the next 

 24 hours neither autolysis nor further growth was 

 to be observed. From the filtrate of such cultures 

 it is possible to isolate a factor (probably 

 polypeptide) which inhibits the growth of the 

 producing strain. The inhibiting effect can be 

 antagonized with proteins or with denaturated 

 proteins. 



The mutant C-46 (Am+) and the B. subtilis 

 wild types grow well on a synthetic medium in 

 which the sole nitrogen source in (NH4)2S04. 

 In these cultures autolysis does not take place. 



The activity of ALA-dehydrogenase, which — 

 according to literature — probably plays a role 

 in the ammonia assimilation has been deter- 

 mined in the lysozym-lysat of cells. 



Inthelysate of (Am - ) cells active (100 per cent) 

 ALA-dehydrogenase, in the lysate of wild type 

 reduced (10 per cent) ALA-dehydrogenase have 

 been found. It is not possible to find ALA- 

 dehydrogenase in the lysozym-lysat of C-46 

 (Am + ) cells. 



The results indicate that in the case of B. sub- 

 tilis the ammonia is not assimilated by means 

 of ALA-dehydrogenase. Presumably the re- 

 pression of the process of ammonia assimilation 

 is simultaneous with the induction of ALA- 

 dehydrogenase. 



1. B.B. Res. Comm. 5, 171, 1961. 



3.42. The Initial Events in Transduction of Galactose 

 Fermentation in Salmonella typhimurium Cell. 



J. Hubacek (Prague, Czechoslovakia). 



3.41. Inheritable Changes in the Nitrogen Assimila- 

 tion of Bacillus subtilis. Istvan Turtoczky 

 and Imre Fedorcsak (Budapest, Hungary). 



The growing and the nitrogen assimilation 

 of B. subtilis C-46 (Am") and C-46 (Am+) 

 as well as B. subtilis wild types have been 

 studied in aerated synthetic medium containing 

 different nitrogen sources. 



The mutant C-46 (Am - ) is not able to the assim- 

 ilation of ammonia. It requires glutamic acid 

 to its growth. In a medium in which the sole 

 nitrogen source is glutamic acid, autolyis takes 

 place regularly in the 18th hour. In the filtrate 

 of autolysat it has not been possible to find the 

 presence of infective phage particles. The auto- 

 lysis does not take place if (NHi) 2 S04 or 

 NaHCC»3 is also present in the medium besides 

 glutamic acid; or if 20-30 vol. per cent CO2 is 

 mixed to the air used for aeration. The autolysis 

 does not occur if the nitrogen source in the 

 medium is only glutamic acid but if the Mg ++ 

 concentration of the medium is reduced from 

 1.0 mMmg/l.toO.l mMmg/liter. In this case in the 



The frequency of the transduced cells is reduced 

 by the transfer of the Salmonella typhimurium 

 recipient cells in the early period after the adsorp- 

 tion of the transducing phage from a complete 

 to a minimal medium and subsequent cultivation 

 for 90 min at 37°C. The potentially transduced 

 cells are most sensitive to this treatment at the 

 onset of transduction process (3 min after the 

 adsorption of the phage) and then after cultiva- 

 tion in compit-te medium the sensitivity gradually 

 decreases. After 90 min cultivation in complete 

 medium the frequency of transduction is practi- 

 cally not influenced by the transfer of the cells to 

 minimal medium. 



In order to time the period of the incorporation 

 of the transducing element its elimination in the 

 non-integrated form has been followed using 

 acriflavine. It was shown that the incorporation 

 requires the multiplication of the cells and takes 

 place during the period from the onset of growth 

 up to 110-120 min of cultivation (2-3 divisions). 

 The sensitive phase of transduced cells to the 

 minimal medium precedes this incorporation 

 event. We assume, therefore, that the reduced 



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