Differential Responses to Amino Acids in Bacterial Growth

Author(s):  
GERRIT TOENNIES
2019 ◽  
Vol 7 (12) ◽  
pp. 693 ◽  
Author(s):  
Ting Li ◽  
Zhaohong Zhan ◽  
Yunuan Lin ◽  
Maojuan Lin ◽  
Qingbiao Xie ◽  
...  

Xanthomonas oryzae pv. oryzae (Xoo) is the causal agent of rice bacterial blight disease, which causes a large reduction in rice production. The successful interaction of pathogens and plants requires a particular nutrient environment that allows pathogen growth and the initiation of both pathogen and host responses. Amino acid synthesis is essential for bacterial growth when bacteria encounter amino acid-deficient environments, but the effects of amino acid synthesis on Xoo pathogenicity are unclear. Here, we systemically deleted the essential genes (leuB, leuC, leuD, ilvC, thrC, hisD, trpC, argH, metB, and aspC) involved in the synthesis of different amino acids and analyzed the effects of these mutations on Xoo virulence. Our results showed that leucine, isoleucine, valine, histidine, threonine, arginine, tryptophan, and cysteine syntheses are essential to Xoo infection. We further studied the role of leucine in the interaction between pathogens and hosts and found that leucine could stimulate some virulence-related responses and regulate Xoo pathogenicity. Our findings highlight that amino acids not only act as nutrients for bacterial growth but also play essential roles in the Xoo and rice interaction.


2003 ◽  
Vol 4 (1) ◽  
pp. 23 ◽  
Author(s):  
U. CHRISTAKI ◽  
F.V. WAMBEKE ◽  
M. BIANCHI

Heterotrophic bacterial growth and substrate utilization were studied in March and September of 1997 in the oligotrophic Aegean Sea. Maximum velocities of ectoproteolytic activity (ectoaminopeptidase ctivity, EAP), as well as amino acid assimilation and respiration rates (AA-A, AA-R) were measured along with bacterial production (protein synthesis). At the northern stations which are influenced by the input of the Black Sea waters, rates at 5 m depth of EAP, AA-A and bacterial production were 2 to 3 times higher than at southern stations. Influenced by the Black Sea water, mean bacterial numbers in the 0-100 m layer showed typical oceanic concentrations averaging 0.7 x 10 6 cells ml -1 . These values, along with low bacterial production rates (30 ng C l -1 h -1 ) implied slow growth for bacteria and/or that a large number among them were inactive. Neither bacterial abundance nor production were correlated with primary production. The percentage of amino acids respired was higher in September compared to March, particularly in the northern Aegean (mean 69 %). The enzyme kinetic analysis showed a biphasic model, the transition between the high and low affinity enzymes being obtained at 50 ΜM. Ectoaminopeptidase activity was weakly correlated with bacterial production (p < 0.05), but strongly correlated with respiration rates of amino acids (p < 0.001), suggesting that the substrate used was devoted to maintain energy requirements.


2016 ◽  
Vol 82 (20) ◽  
pp. 6150-6157 ◽  
Author(s):  
Yuichi Oogai ◽  
Masaya Yamaguchi ◽  
Miki Kawada-Matsuo ◽  
Tomoko Sumitomo ◽  
Shigetada Kawabata ◽  
...  

ABSTRACTStaphylococcus aureusis a human pathogen, andS. aureusbacteremia can cause serious problems in humans. To identify the genes required for bacterial growth in calf serum (CS), a library ofS. aureusmutants with randomly inserted transposons were analyzed for growth in CS, and the aspartate semialdehyde dehydrogenase (asd)-inactivated mutant exhibited significantly reduced growth in CS compared with the wild type (WT). The mutant also exhibited significantly reduced growth in medium, mimicking the concentrations of amino acids and glucose in CS. Asd is an essential enzyme for the biosynthesis of lysine, methionine, and threonine from aspartate. We constructed inactivated mutants of the genes for lysine (lysA), methionine (metE), and threonine (thrC) biosynthesis and found that the inactivated mutants oflysAandthrCexhibited significantly lower growth in CS than the WT, but the growth of themetEmutant was similar to that of the WT. The reduced growth of theasdmutant was recovered by addition of 100 μg/ml lysine and threonine in CS. These results suggest thatS. aureusrequires lysine and threonine biosynthesis to grow in CS. On the other hand, theasd-,lysA-,metE-, andthrC-inactivated mutants exhibited significantly reduced growth in mouse serum compared with the WT. In mouse bacteremia experiments, theasd-,lysA-,metE-, andthrC-inactivated mutants exhibited attenuated virulence compared with WT infection. In conclusion, our results suggest that the biosynthesis ofde novoaspartate family amino acids, especially lysine and threonine, is important for staphylococcal bloodstream infection.IMPORTANCEStudying the growth of bacteria in blood is important for understanding its pathogenicity in the host.Staphylococcus aureussometimes causes bacteremia or sepsis. However, the factors responsible forS. aureusgrowth in the blood are not well understood. In this study, using a library of 2,914 transposon-insertional mutants in theS. aureusMW2 strain, we identified the factors responsible for bacterial growth in CS. We found that inactivation of the lysine and threonine biosynthesis genes led to deficient growth in CS. However, the inactivation of these genes did not affectS. aureusgrowth in general medium. Because the concentration of amino acids in CS is low compared to that in general bacterial medium, our results suggest that lysine and threonine biosynthesis is important for the growth ofS. aureusin CS. Our findings provide new insights forS. aureusadaptation in the host and for understanding the pathogenesis of bacteremia.


1923 ◽  
Vol 21 (4) ◽  
pp. 376-385 ◽  
Author(s):  
G. A. Wyon ◽  
J. W. McLeod

While amino-acids in appropriate concentrations have long been known as valuable aids to bacterial growth, it does not appear to have been recognised that in relatively low concentrations they are often inhibitory.Inhibition has been shown to occur with 10 out of 11 single amino-acids tested and with certain mixtures rich in amino-acids. The inhibitory concetration varies from 11 to 130 millimols per litre, or from 0·2 to 2%(wt./vol. ). It is of some intrest that the amino-acids inhibitory in the lowest concentration were the cyclic compounds—histidine, tyrosine, tryphane, phenylalamine. Of the chain compounds tested cystine was the most inhibitory.Several organisus belonging to various groups of bacteria are susceptible of inhibition by amino-acids; certain intestinal organisms are not susceptible. The effect cannot be attributed to the physical effects of high concentration.There is an apparent divergence between our results and those of workers who have recommended tryptic digests for stimulating the growth of some of the bacteria here shown to be readily inhibited by amino-acids. A suggested explanation of this divergence is that it is the products of partial protein digestion, the polypetides, which are mainly responsible for the effect of stimulating growth, not the amino-acids. A “polypeptide medium” might prove particularly valuable for bacterial growth.A metabolism experiment with glycine in high but sub-inhibitory concentration showed that the amino-acid is broken down by Staphylococcus aureus, at this concentration.


2007 ◽  
Vol 189 (7) ◽  
pp. 2677-2682 ◽  
Author(s):  
Lei Liu ◽  
Jian-Feng Wu ◽  
Ying-Fei Ma ◽  
Sheng-Yue Wang ◽  
Guo-Ping Zhao ◽  
...  

ABSTRACT Comamonas sp. strain CNB-1 degrades nitrobenzene and chloronitrobenzene via the intermediates 2-aminomuconate and 2-amino-5-chloromuconate, respectively. Deamination of these two compounds results in the release of ammonia, which is used as a source of nitrogen for bacterial growth. In this study, a novel deaminase was purified from Comamonas strain CNB-1, and the gene (cnbZ) encoding this enzyme was cloned. The N-terminal sequence and peptide fingerprints of this deaminase were determined, and BLAST searches revealed no match with significant similarity to any functionally characterized proteins. The purified deaminase is a monomer (30 kDa), and its V max values for 2-aminomuconate and 2-amino-5-chloromuconate were 147 μmol·min−1·mg−1 and 196 μmol·min−1·mg−1, respectively. Its catalytic products from 2-aminomuconate and 2-amino-5-chloromuconate were 2-hydroxymuconate and 2-hydroxy-5-chloromuconate, respectively, which are different from those previously reported for the deaminases of Pseudomonas species. In the catalytic mechanism proposed, the α-carbon and nitrogen atoms (of both 2-aminomuconate and 2-amino-5-chloromuconate) were simultaneously attacked by a hydroxyl group and a proton, respectively. Homologs of cnbZ were identified in the genomes of Bradyrhizobium japonicum, Rhodopseudomonas palustris, and Roseiflexus sp. strain RS-1; these genes were previously annotated as encoding hypothetical proteins of unknown function. It is concluded that CnbZ represents a novel enzyme that deaminates xenobiotic compounds and/or α-amino acids.


1994 ◽  
Vol 218 (1) ◽  
pp. 204-209 ◽  
Author(s):  
W.M. Jones ◽  
D. Ringe ◽  
K. Soda ◽  
J.M. Manning
Keyword(s):  

2015 ◽  
Vol 78 (4) ◽  
pp. 819-824 ◽  
Author(s):  
SHIGENOBU KOSEKI ◽  
NOBUTAKA NAKAMURA ◽  
TAKEO SHIINA

Under osmotic stress, bacterial cells uptake compatible solutes such as glycine-betaine to maintain homeostasis. It is unknown whether incompatible solutes exist that are similar in structure to compatible solutes but have adverse physiological effects on bacterial physiology. The objective of this study was to evaluate solute incompatibility of various amino acids against bacterial growth. Bacterial growth was evaluated by changes in optical density at 595 nm in peptone-yeast-glucose (PYG) broth. Twenty-three amino acids with l and/or d isomers were examined for the effect of bacterial growth inhibition. Among the various amino acids examined, d-tryptophan (~40 mM) in PYG broth supplemented with 0 to 4% (wt/vol) salt inhibited the growth of Listeria monocytogenes, Salmonella enterica, and Escherichia coli O157:H7 at 25°C. d-Tryptophan (30 to 40 mM) completely inhibited the growth of E. coli O157:H7 and Salmonella in the presence of &gt;3% salt, but the growth of L. monocytogenes was not completely inhibited under the same conditions. Low concentrations of salt (0 to 2% NaCl) with d-tryptophan did not significantly inhibit the growth of all bacteria except L. monocytogenes, which was relatively inhibited at 0% NaCl. The effect of d-tryptophan differed depending on the bacterial species, illustrating the difference between gram-positive and gram-negative bacteria. These results indicate that the uptake of d-tryptophan as a compatible solute during osmotic stress may inhibit bacterial growth. The antibacterial effect of d-tryptophan found in this study suggests that d-tryptophan could be used as a novel preservative for controlling bacterial growth in foods.


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