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Fulltext Evaluation of 3M™ loop-mediated isothermal amplification-based kit and 3M™ ready-to-use plating system for detection of Listeria in naturally contaminated leafy vegetables, chicken, and their related processing environments

Abatcha MG, Tan PL, Chuah LO, Rusul G, Chandraprasad SR, Effarizah ME

Food Sci Biotechnol, 2020 Aug;29(8):1141-1148.
PMID: 32670668 DOI: 10.1007/s10068-020-00762-2

The effectiveness of two different rapid methods involving the 3M™ molecular detection assay Listeria and the 3M™ Petrifilm environmental Listeria Plate were evaluated for the rapid detection of Listeria from naturally contaminated vegetables and chicken-processing environments against the standard culture-based method. A total of 178 samples were examined for the presence of Listeria. A total of 47/178 (26.4%) by standard ISO culture-based method (EN ISO 11290-1), 42/178 (23.6%) by 3M™ MDA Listeria and 40/178 (22.5%) by 3M™ Petrifilm EL Plate showed positive results, respectively. The accuracy, sensitivity, specificity, positive predictive value, and negative predictive value for 3M™ MDA Listeria and 3M™ Petrifilm EL Plate were 97.2, 89.4, 99.3, 97.7, 96.4% and 96.1, 85.1, 100.0, 100.0, 94.9%, respectively. Based on the Cohen's Kappa value, there was a complete and robust concordance between 3M™ MDA Listeria (0.911) and 3M™ Petrifilm EL Plates (0.894) as compared to the standard culture-based method.
Antibiotic susceptibility and molecular characterization of Salmonella enterica serovar Paratyphi B isolated from vegetables and processing environment in Malaysia

Abatcha MG, Effarizah ME, Rusul G

Int J Food Microbiol, 2019 Feb 02;290:180-183.
PMID: 30342248 DOI: 10.1016/j.ijfoodmicro.2018.09.021

Salmonella enterica serovar Paratyphi B (S. Paratyphi B) is a major foodborne pathogen distributed all over the world. However, little is known about the antibiotic resistance, genetic relatedness and virulence profile of S. Paratyphi B isolated from leafy vegetables and the processing environment in Malaysia. In this study, 6 S. Paratyphi B isolates were recovered from different vegetables and drain water of processing areas obtained from fresh food markets in Malaysia. The isolates were characterized by antibiogram, Pulsed-field gel electrophoresis (PFGE) and virulence genes. Antibiotic susceptibility test showed that 3 of the isolates were resistant to the antibiotics. These include S. Paratyphi B SP251 isolate, which was resistant to chloramphenicol, ampicillin, sulfonamides and streptomycin; Isolate SP246 which was resistant to chloramphenicol, sulfonamides and streptomycin and Isolate SP235 showing resistance to nalidixic acid only. PFGE subtyped the 6 S. Paratyphi B isolates into 6 distinct XbaI-pulsotypes, with a wide range of genetic similarity (0.55 to 0.9). The isolates from different sources and fresh food markets location were genetically diverse. Thirteen (tolC, orgA, spaN, prgH, sipB, invA, pefA, sofB, msgA, cdtB, pagC, spiA and spvB) out of the 17 virulence genes tested were found in all of the S. Paratyphi B isolates. Another gene (lpfC), was found only in one isolate (SP051). None of the isolates possessed sifA, sitC and ironN genes. In summary, this study provides unique information on antibiotic resistance, genetic relatedness, and virulotyping of S. Paratyphi B isolated from leafy vegetables and processing environment.
Fulltext Data on antibiogram and resistance genes harboured bySalmonellastrains and their Pulsed-field gel electrophoresis clusters

Chuah LO, Shamila Syuhada AK, Mohamad Suhaimi I, Farah Hanim T, Rusul G

Data Brief, 2018 Apr;17:698-702.
PMID: 29511712 DOI: 10.1016/j.dib.2018.01.098

This article describes the Pulsed-field gel electrophoresis clustering of the predominantSalmonellastrains (Salmonellaser. Albany,Salmonellaser. Brancaster, andSalmonellaser. Corvallis) isolated from poultry and processing environment in wet market and small-scale processing plant in Penang and Perlis, the northern states of Malaysia. Agar disk diffusion assay was performed to determine the phenotypic antibiotic resistance of theseSalmonellastrains. The most common antibiograms among the three predominantSalmonellaserovars were reported. The presence of integrase genes and antibiotic resistance genes conferring to resistance against β-lactams, aminoglycosides, tetracyclines, quinolones, sulphonamides and chloramphenicol, was detected via PCR amplification.
Corrigendum: Floricoccus tropicus gen. nov., sp. nov. and Floricoccus penangensis sp. nov. isolated from fresh flowers of durian tree and hibiscus

Chuah LO, Yap KP, Shamila-Syuhada AK, Thong KL, Ahmad R, Liong MT, et al.

Int J Syst Evol Microbiol, 2018 03;68(3):974.
PMID: 29493487 DOI: 10.1099/ijsem.0.002582
Genetic relatedness, antimicrobial resistance and biofilm formation of Salmonella isolated from naturally contaminated poultry and their processing environment in northern Malaysia

Chuah LO, Shamila Syuhada AK, Mohamad Suhaimi I, Farah Hanim T, Rusul G

Food Res Int, 2018 03;105:743-751.
PMID: 29433269 DOI: 10.1016/j.foodres.2017.11.066

We investigated the genetic relatedness, antibiotic resistance and biofilm-producing ability of 114 strains of Salmonella, belonged to three serotypes (Corvallis, Brancaster and Albany), isolated from naturally contaminated poultry and their environment in wet markets and smale-scale processing plant from northern Malaysia. Pulsed-field gel electrophoresis revealed that Salmonella strains isolated from various wet markets were clonally related, suggesting the widespread dissemination of these three serotypes in northern Malaysia. All except one strain of Salmonella were resistant to more than two classes of antibiotics, hence regarded as multidrug resistant (MDR). Resistance to sulphonamide (96.5%), ampicillin (89.5%), tetracycline (85.1%), chloramphenicol (75.4%), trimethoprim (68.4%), trimethoprim-sulfamethoxazole (67.5%), streptomycin (58.8%) and nalidixic acid (44.4%) were observed. Resistance determinants, floR, cmlA, tetA, tetB, tetG, temB, blaPSE-1, sul1, sul2, qnrA, qnrS, strA and aadA were detected by PCR among MDR Salmonella strains. Seventy-six strains (66.7%) harboured class-I integrons. The gene cassettes identified were dfrA1, dfrA12, aadA2 and an open reading frame orfC with unknown function. All Salmonella strains produced biofilm and 69.3% of them were strong biofilm-producers. Our findings suggested that most likely, persistent Salmonella colonises various sites in the processing environment by producing biofilm, which leads to their widespread dissemination in wet markets located in northern Malaysia.
Fulltext Effect of pasteurization treatment and calamansi (Fortunella Japonica) juice on the physicochemical, microbiological, and sensory characteristics of black stem sugarcane juice

Chew, S.K., Md Noor, N.A., Maizura, M., Tan, T.C., Rusul, G.

International Food Research Journal, 2018;25(3):1007-1015.
MyJurnal

Sugarcane juice deteriorates rapidly as enzymatic browning and microbial spoilage take place soon after juice extraction. Therefore, the effects of pasteurization treatment (70ºC for 10 minutes) and addition of calamansi juice at different concentrations (0, 1.0, 1.5, and 3.0%, v/v) on the physicochemical (color, pH, total soluble solid, titratable acidity, and peroxidase enzymatic activity), microbiological (total plate count, yeast and mold), and sensory characteristics of black stem sugarcane juice were investigated. Quantitative descriptive analysis (QDA®) was conducted by eight trained panelists to determine the intensity of the sensory attributes of sugarcane juice, such as brownish color, grassy aroma, citrus aroma, sweetness, sourness, sweet aftertaste, and overall acceptability using a 15 cm unstructured line scale. The results showed that the pasteurization treatment significantly (p ˂ 0.05) increased the L* value (lightness) of sugarcane juice at 0% (v/v) of calamansi juice. Increasing the concentration of calamansi juice decreased the pH value and increased the titratable acidity of the sugarcane juice at 5% significance level. The relative effectiveness in reducing the peroxidase (POD) enzymatic activity and microbial load of sugarcane juice was shown after the addition of calamansi juice and pasteurization treatment, respectively. Significant (p ˂ 0.05) changes in the intensity of brownish color, grassy aroma, and sweet aftertaste of sugarcane juice were observed after the pasteurization treatment at 0% (v/v) calamansi juice; whereas, the addition of calamansi juice at different concentrations increased the intensity of citrus aroma and sourness, but decreased the intensity of grassy aroma and sweet aftertaste of sugarcane juice at 5% significance level. Hence, pasteurization treatment coupled with the addition of 1.5% (v/v) calamansi juice was effective in achieving microbial stability and consumer’s acceptability on sugarcane juice.
Floricoccus tropicus gen. nov., sp. nov. and Floricoccus penangensis sp. nov. isolated from fresh flowers of durian tree and hibiscus

Chuah LO, Yap KP, Shamila-Syuhada AK, Thong KL, Ahmad R, Liong MT, et al.

Int J Syst Evol Microbiol, 2017 Dec;67(12):4979-4985.
PMID: 29034853 DOI: 10.1099/ijsem.0.002386

Three strains of Gram-staining-positive, coccus-shaped, lactic acid bacteria, designated as HibF3T, HibF2 and HibF5 were isolated from fresh flowers of hibiscus, and a fourth, DF1T, was isolated from fresh flowers of durian tree, in Penang, Malaysia. Taxonomic characterisation was performed by polyphasic analysis. Sequence similarities of the 16S rRNA gene and the housekeeping rpoA and pheS genes of these strains with their closely-related lactococcal and streptococcal relatives were 92-94, 78 and 81 %, respectively. The results of phylogenetic analysis indicated that strains DF1T, HibF2, HibF5 and HibF3T were clustered together but were clearly separated from species of the genera Streptococcus and Lactococcus, indicating that they represent members of a novel genus of the family Streptococcaceae. Calculation of average nucleotide identity (ANI) values between the genomes of DF1T and HibF3T yielded values of 92.50-92.93 %. ANI values below the cut-off value and distinctive chemotaxonomic characteristics supported the hypothesis that these strains represented two novel species. Major cellular fatty acids in DF1T, HibF2 and HibF5 were C18 : 1ω7c and C16 : 0, while C12 : 0 and C14 : 0 were also dominant, in addition to C18 : 1ω7c and C16 : 0, in HibF3T. A novel genus is proposed with the name Floricoccus gen. nov. which consists of two species, Floricoccus tropicus sp. nov as the type species, and Floricoccus penangensis sp. nov. The respective type strains are DF1T (=LMG 29833T=JCM 31733T) and HibF3T (=LMG 29831T=DSM 31735T).
Fulltext Prevalence of Salmonella in poultry processing environments in wet markets in Penang and Perlis, Malaysia

Nidaullah H, Abirami N, Shamila-Syuhada AK, Chuah LO, Nurul H, Tan TP, et al.

Vet World, 2017 Mar;10(3):286-292.
PMID: 28435190 DOI: 10.14202/vetworld.2017.286-292

AIM: The aim of this study was to determine the prevalence of various Salmonella serotypes in chickens, carcass contact surfaces as well as environmental samples collected from wet markets and small scale processing plant.
MATERIALS AND METHODS: A total of 182 poultry and environmental samples were collected at random on separate occasions from wet markets and small scale processing plant, during the period of October 2014 to July 2015 in Penang and Perlis, Malaysia. The samples were analyzed for the presence of Salmonella using ISO 6579:2002 conventional culture-based method. Presumptive Salmonella colonies were subjected to various biochemical tests (such as triple sugar iron and lysine iron test), serologically confirmed using polyvalent O and H antisera and further serotyped at Public Health Laboratory, Ministry of Health, Perak, Malaysia.
RESULTS: Salmonella serotypes were isolated from 161 out of 182 samples (88.46%) with 100% prevalence in the whole chicken carcass and chicken cuts - as well as transport crate, cage, drum, knife, chopping board, display table, floor, bench wash water, wash water, and drain water. Salmonella was isolated from 91.67%, 83.33%, and 66.67% of defeathering machines, drain swabs, and apron, respectively. 17 serotypes were isolated in this study with Salmonella Albany (57/161), Salmonella Corvallis (42/161), and Salmonella Brancaster (37/161) being the predominant serovars.
CONCLUSION: The most carcass contact and environmental samples collected along the wet market chicken processing line were consistently contaminated with Salmonella. This indicates that Salmonella has established itself in poultry processing environments by colonizing the surfaces of the equipment and survives in these environments by establishing biofilms. Our results highlight the need of implementing strict hygiene and sanitation standards to reduce the incidence of Salmonella. The prevalence of Salmonella in poultry can be reduced effectively by identifying and eliminating the sources and contamination sites during slaughter and processing of poultry.
Physio-chemical, microbiological properties of tempoyak and molecular characterisation of lactic acid bacteria isolated from tempoyak

Chuah LO, Shamila-Syuhada AK, Liong MT, Rosma A, Thong KL, Rusul G

Food Microbiol, 2016 Sep;58:95-104.
PMID: 27217364 DOI: 10.1016/j.fm.2016.04.002

This study aims to determine physio-chemical properties of tempoyak, characterise the various indigenous species of lactic acid bacteria (LAB) present at different stages of fermentation and also to determine the survival of selected foodborne pathogens in tempoyak. The predominant microorganisms present in tempoyak were LAB (8.88-10.42 log CFU/g). Fructobacillus durionis and Lactobacillus plantarum were the dominant members of LAB. Other LAB species detected for the first time in tempoyak were a fructophilic strain of Lactobacillus fructivorans, Leuconostoc dextranicum, Lactobacillus collinoides and Lactobacillus paracasei. Heterofermentative Leuconostoc mesenteroides and F. durionis were predominant in the initial stage of fermentation, and as fermentation proceeded, F. durionis remained predominant, but towards the end of fermentation, homofermentative Lb. plantarum became the predominant species. Lactic, acetic and propionic acids were present in concentrations ranging from 0.30 to 9.65, 0.51 to 7.14 and 3.90 to 7.31 mg/g, respectively. Genotyping showed a high degree of diversity among F. durionis and Lb. plantarum isolates, suggesting different sources of LAB. All tested Lb. plantarum and F. durionis (except for one isolate) isolates were multidrug resistant. Salmonella spp., Listeria monocytogenes and Staphylococcus aureus were not detected. However, survival study showed that these pathogens could survive up to 8-12 days. The results aiming at improving the quality and safety of tempoyak.
Antibiotic Application and Emergence of Multiple Antibiotic Resistance (MAR) in Global Catfish Aquaculture

Chuah LO, Effarizah ME, Goni AM, Rusul G

Curr Environ Health Rep, 2016 Jun;3(2):118-27.
PMID: 27038482 DOI: 10.1007/s40572-016-0091-2

Catfish is one of the most cultivated species worldwide. Antibiotics are usually used in catfish farming as therapeutic and prophylactic agents. In the USA, only oxytetracycline, a combination of sulfadimethoxine and ormetoprim, and florfenicol are approved by the Food Drug Administration for specific fish species (e.g., catfish and salmonids) and their specific diseases. Misuse of antibiotics as prophylactic agents in disease prevention, however, is common and contributes in the development of antibiotic resistance. Various studies had reported on antibiotic residues and/or resistance in farmed species, feral fish, water column, sediments, and, in a lesser content, among farm workers. Ninety percent of the world aquaculture production is carried out in developing countries, which lack regulations and enforcement on the use of antibiotics. Hence, efforts are needed to promote the development and enforcement of such a regulatory structure. Alternatives to antibiotics such as antibacterial vaccines, bacteriophages and their lysins, and probiotics have been applied to curtail the increasing emergence of antibiotic-resistant bacteria due to the imprudent application of antibiotics in aquaculture.
Fulltext Genetic Relatedness of Salmonella Serovars Isolated from Catfish (Clarias gariepinus) and Tilapia (Tilapia mossambica) Obtained from Wet Markets and Ponds in Penang, Malaysia

Budiati T, Rusul G, Wan-Abdullah WN, Chuah LO, Ahmad R, Thong KL

J Food Prot, 2016 Apr;79(4):659-65.
PMID: 27052872 DOI: 10.4315/0362-028X.JFP-15-372

A total of 43 Salmonella enterica isolates belonging to different serovars (Salmonella Albany, Salmonella Agona, Salmonella Corvallis, Salmonella Stanley, Salmonella Typhimurium, Salmonella Mikawasima, and Salmonella Bovismorbificans) were isolated from catfish (Clarias gariepinus) and tilapia (Tilapia mossambica) obtained from nine wet markets and eight ponds in Penang, Malaysia. Thirteen, 19, and 11 isolates were isolated from 9 of 32 catfish, 14 of 32 tilapia, and 11 of 44 water samples, respectively. Fish reared in ponds were fed chicken offal, spoiled eggs, and commercial fish feed. The genetic relatedness of these Salmonella isolates was determined by random amplified polymorphic DNA PCR (RAPD-PCR) using primer OPC2, repetitive extragenic palindromic PCR (REP-PCR), and pulsed-field gel electrophoresis (PFGE). Composite analysis of the RAPD-PCR, REP-PCR, and PFGE results showed that the Salmonella serovars could be differentiated into six clusters and 15 singletons. RAPD-PCR differentiated the Salmonella isolates into 11 clusters and 10 singletons, while REP-PCR differentiated them into 4 clusters and 1 singleton. PFGE differentiated the Salmonella isolates into seven clusters and seven singletons. The close genetic relationship of Salmonella isolates from catfish or tilapia obtained from different ponds, irrespective of the type of feed given, may be caused by several factors, such as the quality of the water, density of fish, and size of ponds.
Fulltext Effectiveness of ascorbic acid and sodium metabisulfite as anti-browning agent and antioxidant on green coconut water (Cocos nucifera) subjected to elevated thermal processing

Tan, T.C., Cheng, L.H., Bhat, R., Rusul, G., Easa, A.M.

International Food Research Journal, 2015;22(2):631-637.
MyJurnal

Thermal processing of green coconut water (GCW) caused non-enzymic browning and development of rancidity. Effect of the addition of several combinations of ascorbic acid (AA) (0 to 100 ppm) and sodium metabisulfite (SMB) (0 to 30 ppm) on brown discolouration and rancidity of GCW during elevated thermal processing (121°C for 5 min at 15 psi) was investigated. Addition of AA and/or SMB significantly (P
Composition, physicochemical properties and thermal inactivation kinetics of polyphenol oxidase and peroxidase from coconut (Cocos nucifera) water obtained from immature, mature and overly-mature coconut

Tan TC, Cheng LH, Bhat R, Rusul G, Easa AM

Food Chem, 2014 Jan 1;142:121-8.
PMID: 24001821 DOI: 10.1016/j.foodchem.2013.07.040

Composition, physicochemical properties and enzyme inactivation kinetics of coconut water were compared between immature (IMC), mature (MC) and overly-mature coconuts (OMC). Among the samples studied, pH, turbidity and mineral contents for OMC water was the highest, whereas water volume, titratable acidity, total soluble solids and total phenolics content for OMC water were the lowest. Maturity was found to affect sugar contents. Sucrose content was found to increase with maturity, and the reverse trend was observed for fructose and glucose. Enzyme activity assessment showed that polyphenol oxidase (PPO) in all samples was more heat resistant than peroxidase (POD). Compared to IMC and MC, PPO and POD from OMC water showed the lowest thermal resistance, with D83.3°C=243.9s (z=27.9°C), and D83.3°C=129.9s (z=19.5°C), respectively.
Growth properties and cholesterol removal ability of electroporated Lactobacillus acidophilus BT 1088

Lye HS, Khoo BY, Karim AA, Rusul G, Liong MT

J Microbiol Biotechnol, 2012 Jul;22(7):981-9.
PMID: 22580318

This study aimed to evaluate the effects of electroporation on the cell growth, cholesterol removal, and adherence abilities of L. acidophilus BT 1088 and their subsequent passages. The growth of electroporated parent cells increased (P<0.05) by 4.49-21.25% compared with that of the control. This may be attributed to the alteration of cellular membrane. However, growth of first, second, and third passages of treated cells was comparable with that of the control, which may be attributed to the resealing of transient pores on the cellular membrane. Electroporation also increased (P<0.05) assimilation of cholesterol by treated parent cells (>185.40%) and first passage (>21.72%) compared with that of the control. Meanwhile, incorporation of cholesterol into the cellular membrane was also increased (P<0.05) in the treated parent cells (>108.33%) and first passage (>26.67%), accompanied by increased ratio of cholesterol:phospholipids (C:P) in these passages. Such increased ratio was also supported by increased enrichment of cholesterol in the hydrophilic heads, hydrophobic tails, and the interface regions of the membrane phospholipids of both parent and first passage cells compared with that of the control. However, such traits were not inherited by the subsequent second and third passages. Parent cells also showed decreased intestinal adherence ability (P<0.05; decreased by 1.45%) compared with that of the control, without inheritance by subsequent passages of treated cells. Our data suggest that electoporation could be a potential physical treatment to enhance the cholesterol removal ability of lactobacilli that was inherited by the first passage of treated cells without affecting their intestinal adherence ability.
Ultrasound enhanced growth and cholesterol removal of Lactobacillus fermentum FTDC 1311 in the parent cells but not the subsequent passages

Lye HS, Khoo BY, Karim AA, Rusul G, Liong MT

Ultrason Sonochem, 2012 Jul;19(4):901-8.
PMID: 22265020 DOI: 10.1016/j.ultsonch.2011.12.018

The aim of this study was to evaluate the effect of ultrasound on the intestinal adherence ability, cell growth, and cholesterol removal ability of parent cells and subsequent passages of Lactobacillus fermentum FTDC 1311. Ultrasound significantly decreased the intestinal adherence ability of treated parent cells compared to that of the control by 11.32% (P<0.05), which may be due to the protein denaturation upon local heating. Growth of treated parent cells also decreased by 4.45% (P<0.05) immediately upon ultrasound (0-4h) and showed an increase (P<0.05) in the viability by 2.18-2.34% during the later stage of fermentation (12-20 h) compared to that of the control. In addition, an increase (P<0.05) in assimilation of cholesterol (>9.74%) was also observed for treated parent cells compared to that of the control, accompanied by increased (P<0.05) incorporation of cholesterol into the cellular membrane. This was supported by the increased ratio of membrane cholesterol:phospholipids (C:P), saturation of cholesterol in the apolar regions, upper phospholipids regions, and polar regions of membrane phospholipids of parent cells compared to that of the control (P<0.05). However, such traits were not inherited by the subsequent passages of treated cells (first, second, and third passages). Our data suggested that ultrasound treatment could be used to improve cholesterol removal ability of parent cells without inducing permanent damage/defects on treated cells of subsequent passages.
Ultrasound treatment enhances cholesterol removal ability of lactobacilli

Lye HS, Alias KA, Rusul G, Liong MT

Ultrason Sonochem, 2012 May;19(3):632-41.
PMID: 21907608 DOI: 10.1016/j.ultsonch.2011.08.004

This study aimed to evaluate the effect of ultrasound treatment on the cholesterol removing ability of lactobacilli. Viability of lactobacilli cells was significantly increased (P < 0.05) immediately after treatment, but higher intensity of 100 W and longer duration of 3 min was detrimental on cellular viability (P < 0.05). This was attributed to the disruption of membrane lipid bilayer, cell lysis and membrane lipid peroxidation upon ultrasound treatment at higher intensity and duration. Nevertheless, the effect of ultrasound on membrane properties was reversible, as the viability of ultrasound-treated lactobacilli was increased (P < 0.05) after fermentation at 37 °C for 20 h. The removal of cholesterol by ultrasound-treated lactobacilli via assimilation and incorporation of cholesterol into the cellular membrane also increased significantly (P < 0.05) upon treatment, as observed from the increased ratio of membrane C:P. Results from fluorescence anisotropies showed that most of the incorporated cholesterol was saturated in the regions of phospholipids tails, upper phospholipids, and polar heads of the membrane bilayer.
Prevalence, antibiotic resistance and RAPD typing of Campylobacter species isolated from ducks, their rearing and processing environments in Penang, Malaysia

Adzitey F, Rusul G, Huda N, Cogan T, Corry J

Int J Food Microbiol, 2012 Mar 15;154(3):197-205.
PMID: 22285201 DOI: 10.1016/j.ijfoodmicro.2012.01.006

We report for the first time on the prevalence, antibiotic resistance and RAPD types of Campylobacter species in ducks and duck related environmental samples in Malaysia. Samples were examined by enrichment in Bolton Broth followed by plating onto modified Charcoal Cefoperazone Deoxycholate agar (mCCDA) and/or plating directly onto mCCDA. A total of 643 samples were screened, and the prevalence of Campylobacter spp. in samples from different sources ranged from 0% to 85%. The method of isolation had a significant (P<0.05) effect on the isolation rate. One hundred and sixteen Campylobacter isolates, comprising of 94 Campylobacter jejuni, 19 Campylobacter coli and three Campylobacter lari, were examined for their sensitivity to 13 antibiotics. Majority of the C. jejuni isolates were resistant to cephalothin (99%), tetracycline (96%), suphamethoxazole/trimethoprim (96%), and very few were resistant to gentamicin (5%), chloramphenicol (7%) and erythromycin (1%). All C. coli isolates were resistant to cephalothin, nalidixic acid, norfloxacin and tetracycline but susceptible to chloramphenicol, erythromycin and gentamicin. The three C. lari isolates were resistant to all the antibiotics tested except chloramphenicol and gentamicin (1/3 and 2/3 susceptible, respectively). Genetic diversity of Campylobacter isolates were determined using random amplification of polymorphic DNA (RAPD). C. jejuni and C. coli isolates belong to fifty-eight and twelve RAPD types, respectively.
Electroporation enhances the ability of lactobacilli to remove cholesterol

Lye HS, Karim AA, Rusul G, Liong MT

J Dairy Sci, 2011 Oct;94(10):4820-30.
PMID: 21943733 DOI: 10.3168/jds.2011-4426

The objective of the present study was to evaluate the effect of electroporation on the membrane properties of lactobacilli and their ability to remove cholesterol in vitro. The growth of lactobacilli cells treated at 7.5 kV/cm for 4 ms was increased by 0.89 to 1.96 log(10) cfu/mL upon fermentation at 37 °C for 20 h, the increase being attributed to the reversible and transient formation of pores and defragmentation of clumped cells. In addition, an increase of cholesterol assimilation as high as 127.2% was observed for most cells electroporated at a field strength of 7.5 kV/cm for 3.5 ms compared with a lower field strength of 2.5 kV/cm. Electroporation also increased the incorporation of cholesterol into the cellular membrane, as shown by an increased cholesterol:phospholipids ratio (50.0-59.6%) upon treatment at 7.5 kV/cm compared with treatment at 2.5 kV/cm. Saturation of cholesterol was observed in different regions of the membrane bilayer such as upper phospholipids, apolar tail, and polar heads, as indicated by fluorescence anisotropy using 3 fluorescent probes. Electroporation could be a useful technique to increase the ability of lactobacilli to remove cholesterol for possible use as cholesterol-lowering adjuncts in the future.
Removal of cholesterol by lactobacilli via incorporation and conversion to coprostanol

Lye HS, Rusul G, Liong MT

J Dairy Sci, 2010 Apr;93(4):1383-92.
PMID: 20338415 DOI: 10.3168/jds.2009-2574

Fifteen strains of Lactobacillus and Bifidobacterium were screened based on their ability to adhere to hydrocarbons via the determination of cellular hydrophobicity. Lactobacillus acidophilus ATCC 314, L. acidophilus FTCC 0291, Lactobacillus bulgaricus FTCC 0411, L. bulgaricus FTDC 1311, and L. casei ATCC 393 showed greater hydrophobicity and, thus, were selected for examination of cholesterol-removal properties. All selected strains showed changes in cellular fatty acid compositions, especially total fatty acids and saturated and unsaturated fatty acids in the presence of cholesterol compared with those grown in the absence of cholesterol. In addition, we found that cells grown in media containing cholesterol were more resistant to sonication and enzymatic lysis compared with those grown without cholesterol. We further evaluated the location of the incorporated cholesterol via the insertion of fluorescence probes into the cellular membrane. In general, enrichment of cholesterol was found in the regions of the phospholipid tails, upper phospholipids, and polar heads of the cellular membrane phospholipid bilayer. Our results also showed that lactobacilli were able to reduce cholesterol via conversion of cholesterol to coprostanol, aided by the ability of strains to produce cholesterol reductase. Our results provided experimental evidence to strengthen the hypothesis that probiotics could remove cholesterol via the incorporation of cholesterol into the cellular membrane and conversion of cholesterol to coprostanol. The strains studied may be potential health adjunct cultures in fermented dairy products with possible in vivo hypocholesterolemic effects.
Inhibitory effect of oxalic acid on bacterial spoilage of raw chilled chicken

Anang DM, Rusul G, Radu S, Bakar J, Beuchat LR

J Food Prot, 2006 Aug;69(8):1913-9.
PMID: 16924917

Oxalic acid was evaluated as a treatment for reducing populations of naturally occurring microorganisms on raw chicken. Raw chicken breasts were dipped in solutions of oxalic acid (0, 0.5, 1.0, 1.5, and 2.0%, wt/vol) for 10, 20, and 30 min, individually packed in oxygen-permeable polyethylene bags, and stored at 4 degrees C. Total plate counts of aerobic bacteria and populations of Pseudomonas spp. and Enterobacteriaceae on breasts were determined before treatment and after storage for 1, 3, 7, 10, and 14 days. The pH and Hunter L, a, and b values of the breast surface were measured. Total plate counts were ca. 1.5 and 4.0 log CFU/g higher on untreated chicken breasts after storage for 7 and 14 days, respectively, than on breasts treated with 0.5% oxalic acid, regardless of dip time. Differences in counts on chicken breasts treated with water and 1.0 to 2.0% of oxalic acid were greater. Populations of Pseudomonas spp. on chicken breasts treated with 0.5 to 2.0% oxalic acid and stored at 4 degrees C for 1 day were less than 2 log CFU/g (detection limit), compared with 5.14 log CFU/g on untreated breasts. Pseudomonas grew on chicken breasts treated with 0.5% oxalic acid to reach counts not exceeding 3.88 log CFU/g after storage for 14 days. Counts on untreated chicken exceeded 8.83 log CFU/g at 14 days. Treatment with oxalic acid caused similar reductions in Enterobacteriaceae counts. Kocuria rhizophila was the predominant bacterium isolated from treated chicken. Other common bacteria included Escherichia coli and Empedobacter brevis. Treatment with oxalic acid caused a slight darkening in color (decreased Hunter L value), retention of redness (increased Hunter a value), and increase in yellowness (increased Hunter b value). Oxalic acid has potential for use as a sanitizer to reduce populations of spoilage microorganisms naturally occurring on raw chicken, thereby extending chicken shelf life.

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