Influence of genes encoding proton-translocating enzymes on suppression of Salmonella typhimurium growth and colonization

Abstract

Twenty-four-hour-old, aerobically grown, Luria-Bertani broth cultures of Salmonella typhimurium F98 suppressed the growth of a spectinomycin-resistant (Spc r ) derivative of the same strain inoculated at 10 3 CFU ml ؊1 . This growth suppression is genus specific and RpoS independent, and it is not solely a result of nutrient depletion (P. A. Barrow, M. A. Lovell, and L. Zhang-Barber, J. Bacteriol. 178:3072-3076, 1996). Mutations in three genes are shown here to significantly reduce growth suppression under these conditions. The mutations were located in the nuo, cyd, and unc operons, which code for the NADH dehydrogenase I, cytochrome d oxidase, and F 0 F 1 proton-translocating ATPase complexes, respectively. When cultures were grown under strictly anaerobic conditions, only the unc mutant did not suppress growth. Prior colonization of the alimentary tract of newly hatched chickens with the S. typhimurium F98 wild type or nuo or cyd mutants suppressed colonization by an S. typhimurium F98 Spc r derivative inoculated 24 h later. In contrast, the S. typhimurium unc mutant did not suppress colonization. The nuo and unc mutants showed poorer growth on certain carbon sources. The data support the hypothesis that growth suppression operates because of the absence of a utilizable carbon source or electron acceptor.The normal microbial flora of the alimentary tract is a major factor protecting animals and humans against colonization by pathogenic bacteria (17). Newly hatched chickens without an established flora are particularly susceptible to Salmonella infection and colonization. Colonized young chicks often excrete large numbers of salmonellae into their environment for long periods, thus becoming a potential reservoir of infection (7). When chickens reach several weeks of age, the lower alimentary tract is colonized by large numbers of obligate anaerobes which confer increased resistance to the establishment of Salmonella infection. The resistance of young chicks to infection may be artificially increased by oral administration, immediately after hatching, of a suspension or culture of cecal contents obtained from healthy adult birds (23). This phenomenon has been termed "competitive exclusion," and its discovery has led to a search for individual strains of bacteria which can inhibit colonization by pathogens to the same extent as the normal flora. Oral administration of an avirulent Salmonella typhimurium strain to day-old chicks can confer protection against oral infection by a virulent strain (known as colonization inhibition) (8, 10). Colonization inhibition is normally genus specific, is not caused by bacteriophage or bacteriocin activity, and is not a consequence of immunity induced by the first strain (8). Attempts are currently under way to elucidate the mechanisms responsible for this effect. An analogous phenomenon in vitro has been observed with 24-h-old stationaryphase nutrient broth cultures of S. typhimurium (6,8,11). When such cultures are inoculated with small numbers of genetically tagged (antibiot...

Glycogen production by different Salmonella enterica serotypes: contribution of functional glgC to virulence, intestinal colonization and environmental survival

“…For intestinal colonization studies, mutants were used which were resistant to nalidixic acid. The Nal R resistance determinant has previously been shown not to adversely affect growth, virulence or colonization (Barrow et al, 1987c;Zhang-Barber et al, 1997). Lodge et al (1992) Growth media and conditions used.…”

“…The defined mutation in glgC was produced as previously described (Zhang-Barber et al, 1997;Turner et al, 1998). Fragments of the glgC gene were amplified from S. Typhimurium F98 DNA by PCR using the primer pairs Gly01-EcoRI (59-TGAAT-TCGTGAGTTTAGAGAAGAACGA-39) and Gly02-KpnI (59-CAATT-CATACAGGTACCCATCACGCCGAACGCCGT-39), and Gly03-KpnI (59-ATGGGTACCTGTATGAATTGCTGG-39) and Gly04-XbaI (59-CTCTAGACAGCATTTCACGCGTGACCA-39) (restriction sites are underlined).…”

Salmonella infections: immune and non-immune protection with vaccines

“…The mechanism of colonisation-inhibition is also poorly understood, and although an early hypothesis arose from the observation that a similar inhibition could be demonstrated in stationary-phase nutrient broth cultures (Zhang-Barber et al, 1997), interactions with the host, either by competition for sites of adhesion or through stimulation of the innate immune system (van Immerseel et al, 2005), have by no means been discounted. Of these mechanistic explanations neither explains completely the colonisation-inhibition phenomenon, and both may be involved simultaneously.…”

“…Amongst the Salmonellae, not all strains were equally inhibitory. The mechanism was studied using an in vitro system of stationary-phase broth cultures 1991) and it appeared to relate to the use and depletion of carbon sources and other nutrients available under the relevant redox conditions under which the organisms are growing (Zhang-Barber et al, 1997). However, the practical aspects of the effect were immediately apparent and warranted further investigation.…”

Interactions between Heme d and Heme b595 in Quinol Oxidase bd from Escherichia coli: A Photoselection Study Using Femtosecond Spectroscopy

“…There is growing evidence that cytochrome bd expression is a prerequisite for the virulence of many pathogenic bacteria, such as Brucella abortus (5), Shigella spp. (bacillary disentery) (6), and Salmonella typhimurium (7).…”