Determination of optimal liquid medium for enzyme expression by Helicobacter pylori

The use of AlbuMAX II(®) as a blood or serum alternative for the culture of Helicobacter pylori

BACKGROUND

Growth of Helicobacter pyloriin vitro depends on supplementation of the medium with blood or serum. However, these supplements often require frozen storage and can show batch-to-batch variation, resulting in differences in bacterial growth. In this study, we introduce the use of a commercially available, lipid-rich supplement called AlbuMAX II(®) (Gibco BRL, Grand Island, NY, USA) for use as a serum/blood replacement for H. pylori culture.

MATERIALS AND METHODS

The growth of H. pylori on solid and liquid media was examined by comparing growth after supplementation with horse blood, fetal calf serum, β-cyclodextrin or AlbuMAX II(®) (Gibco BRL). Human gastric adenocarcinoma (AGS) cellular responses to H. pylori were measured by NF-κB luciferase assays and IL-8 ELISA.

RESULTS

We show that the growth of H. pylori on both solid and liquid media containing AlbuMAX II(®) (Gibco BRL) were comparable to levels obtained on blood agar or liquid media supplemented with serum. Growth was consistently higher in media supplemented with AlbuMAX II(®) (Gibco BRL) than media containing β-cyclodextrin. Furthermore, bacteria grown in AlbuMAX II(®) (Gibco BRL) induced proinflammatory responses in AGS cells.

CONCLUSIONS

AlbuMAX II(®) (Gibco BRL) can be used as a serum/blood replacement for the cultivation of H. pylori in solid and liquid media. This medium could be useful for an improved understanding of H. pylori metabolism or for antigen production. Furthermore, AlbuMAX II(®) (Gibco BRL) may be suitable for use in remote locations, particularly in areas where frozen storage of serum may be a problem.

A thin-layer liquid culture technique for the growth of Helicobacter pylori

BACKGROUND AND AIMS

Several attempts have been successful in liquid cultivation of Helicobaccter pylori. However, there is a need to improve the growth of H. pylori in liquid media in order to get affluent growth and a simple approach for examining bacterial properties. We introduce here a thin-layer liquid culture technique for the growth of H. pylori.

METHODS

A thin-layer liquid culture system was established by adding liquid media to a 90-mm diameter Petri dish. Optimal conditions for bacterial growth were investigated and then viability, growth curve, and released proteins were examined.

RESULTS

Maximal growth of H. pylori was obtained by adding 3 mL of brucella broth supplemented with 10% horse to a Petri dish. H. pylori grew in both DMEM and RPMI-1640 supplemented with 10% fetal bovine serum and 0.5% yeast extract. Serum-free RPMI-1640 supported the growth of H. pylori when supplemented with dimethyl-beta-cyclodextrin (200 microg/mL) and 1% yeast extract. Under optimal growth, H. pylori grew exponentially for 28 hours, reaching a density of 3.4 OD(600) with a generation time of 3.3 hours. After 24 hours, cultures at a cell density of 1.0 OD(600) contained 1.3 +/- 0.1 x 10(9 )CFU/mL. gamma-Glutamyl transpeptidase, nuclease, superoxide dismutase, and urease were not detected in culture supernatants at 24 hours in thin-layer liquid culture, but were present at 48 hours, whereas alcohol dehydrogenase, alkylhydroperoxide reductase, catalase, and vacuolating cytotoxin were detected at 24 hours.

CONCLUSIONS

Thin-layer liquid culture technique is feasible, and can serve as a versatile liquid culture technique for investigating bacterial properties of H. pylori.

Helicobacter pylori detection and antimicrobial susceptibility testing

The discovery of Helicobacter pylori in 1982 was the starting point of a revolution concerning the concepts and management of gastroduodenal diseases. It is now well accepted that the most common stomach disease, peptic ulcer disease, is an infectious disease, and all consensus conferences agree that the causative agent, H. pylori, must be treated with antibiotics. Furthermore, the concept emerged that this bacterium could be the trigger of various malignant diseases of the stomach, and it is now a model for chronic bacterial infections causing cancer. Most of the many different techniques involved in diagnosis of H. pylori infection are performed in clinical microbiology laboratories. The aim of this article is to review the current status of these methods and their application, highlighting the important progress which has been made in the past decade. Both invasive and noninvasive techniques will be reviewed.

Sphingomyelinase of Helicobacter pylori-induced cytotoxicity in AGS gastric epithelial cells via activation of JNK kinase

The aim of this study was to determine whether the Helicobacter pylori-derived sphigomyelinase (SMase) affects the sphingomyelin pathway and growth in AGS epithelial cells. We showed that the exogenous SMase increased the intracellular level of ceramide in AGS cells and led to rapid stimulation of extracellular signal-regulated kinase (ERK) and c-Jun kinase (JNK) activities. Incubation of AGS cells with H. pylori-derived SMase also resulted in suppression of cell growth and a concomitant induction of apoptosis. Data showed that PD98059 (up to 50 microM), an ERK inhibitor, did not affect the cell viability, whereas the cytotoxicity of exogenous SMase was completely blocked by SP600125, a JNK inhibitor at a concentration of 210 nM. We conclude that the activation of the mitogen-activated protein (MAP) kinases in AGS cells by exogenous H. pylori SMase is a major pathway to mediate the cytotoxicity.