spp. in powdered infant formula has been etiologically linked to meningitis and necrotizing enterocolitis in certain groups of infants. This study aimed to determine whether Yrt2a strain experiencing desiccation stress could enter viable but nonculturable (VBNC) state as well as to examine the expression of genes associated with stress and virulence during the above states. Stress and VBNC conditions were determined based on viability and culturability assays. Expression of genes related to stress (S) and virulence ( and A) was evaluated by real-time PCR. The results showed that Yrt2a entered VBNC 24 days post exposure to 2 h of desiccation treatment. The expression of S, and A genes was up-regulated during stress conditions, suggesting that successfully managed stress to maintain its culturability while maintaining its virulence. The expression of the target genes decreased at VBNC state but remained higher than that of a normal state. These findings reinforce the assumption that undergoing VBNC state maintains its pathogenicity.

Lactic acid b acteria (LAB) have b een isolated fromIndonesian fermented foods such as tempe and tape. Some lactic acid b acteria are known to have health b enefits and as prob iotics. The ob jective of this study was to evaluate the prob iotic potential of lactic acid b acteria isolated from tempe and tape. LAB isolated from tape were evaluated for their tolerance towards low pH (pH 2.0) and 0.5% b ile salt. LAB isolated from tape and tempe resistant to low pH and b ile salt were then evaluated for their antimicrob ial activities against pathogenic b acteria (E. coli ATCC 25922, S. typhimurium ATCC 14028, L. monocytogenes ATCC 7644, S. aureus ATCC 25923 and B. cereus ATCC 11778). The isolates were also tested for their adherence properties, consisting of hidrophob icity test using microb ial adhesion to solvents (MATS) assay, autoaggregation as well as coaggregation b etween LAB and pathogens. The results of this study indicated that three isolates from tape (L. fermentum 1 BK2-5, L. fermentum 2 BK2-7, P. acidilactici NG6-4) showed good tolerance to pH 2.0 and 0.5% b ile salt. L. fermentum S21209 isolated from tempe showed the strongest antimicrob ial activity against the five pathogens tested. Based on the adhesion to xylene, L. fermentum 1 BK 2-5 was categorized as strong hydrophob ic, followed b y L. fermentum S21209 and L. fermentum TS4-5. Meanwhile, L. fermentum TS 4-5, L. fermentum S21209, L. fermentum 1 BK 2-5 and P. pentose-ceus 1 W2SR04 have the highest autoaggregation ab ility. L. fermentum S21209 also had the highest co-aggregation ab ility to the five pathogenic b acteria tested. The ab ility of LAB to coaggregate with all pathogens tested correlated with their strong antimicrob ial properties. Based on the resistance toward low pH and b ile salt, antimicrob ial activity and adherence properties, L. fermentum S21209 from tempe and L. fermentum 1 BK 2-5 from tape are the most potential as prob iotic candidates.

Indonesian kefir grains are potential sources of lactic acid bacteria (LAB) that may act as probiotics with specific functional properties. In this study we explored the potential of the probiotic and cholesterol-lowering effect of LAB isolated from Indonesian kefir grains obtained from Bogor, Bandung, Jakarta, and Yogyakarta. The results revealed that 10 isolates showed considerable survivability at low pH and bile salt with total cell reduction of ~3 log colony-forming units per milliliter after exposure to pH 2.5 and 0.5% (w/v) bile salt for 1 and 3 h, respectively. All strains exhibited strong antimicrobial activities against pathogenic bacteria and were sensitive to a wide spectrum of antibiotics but exhibited weak bile salt hydrolase activity. Identification based on 16S RNA suggested that nine isolates were Lactobacillus kefiri and one was Lactobacillus rhamnosus. The ability of the isolates to reduce cholesterol from the media varied, ranging from 22.08% to 68.75% with the highest reduction shown by L. kefiri JK17. The ability to remove cholesterol from the media decreased greatly in resting and dead cells, ranging from 14.58% to 22.08% in resting cells and from 7.89% to 18.17% in dead cells. It can be concluded that Indonesian kefir grains contain LAB potentially acting as probiotics capable of reducing cholesterol. The cholesterol-lowering effect especially occurs when the cells are metabolically active.

Stability of ultraviolet green fluorescent protein (GFPuv)-labeled Cronobacter sakazakii and C. muytjensii isolated from foods and the effects of the plasmid GFPuv (pGFPuv) on growth were analyzed. PCR analysis and microscopic observation showed that C. sakazakii and C. muytjensii isolates took up the plasmid into cells and expressed the GFPuv gene. All Cronobacter transformants maintained this plasmid after frozen storage and 2 consecutive subcultures. The C. sakazakii FWHd16 transformant was the most stable, while the C. muytjensii FWHd11 transformant was the least stable. All transformants showed nearly identical growth curves during lag, log and stationary phases, compared to wild type parental isolates. The maximum bacterial growth rates (µ max ) of the transformants and parents were similar, indicating that the presence of pGFPuv in transformants did not affect cell growth. Stable GFPuv-labeled Cronobacter has potential for use in tracking bacterial behavior during food handling and drying.

This research was aimed to evaluate the pasting properties of white corn flour made from Anoman 1 and Pulut Harapan varieties as affected by the fermentation process of the corn grits. The fermentation process studied were 1) spontaneous fermentation (SF); 2) fermentation with the addition of a complete starter culture at 0 hour (CC fermentation) and 3) fermentation of (CC) with additional inoculation of starter culture containing amylolytic microorganisms at 16 hours (AC fermentation). The evaluation of pasting properties was done on the flour made from corn grits fermented for 0, 36, 48, and 72 hours. Our results showed that pasting properties of corn flour of Anoman 1 and Pulut Harapan varieties were affected by fermentation process. Addition of starter culture in the fermentation showed more complex effect on the pasting properties and was a function of the fermentation time. Fermentation process of corn grits affected the pasting properties of the resulted flour, both for Anoman I and Pulut Harapan corn varieties. The differences in the effect of fermentation process on the pasting properties were due to the different amylose/amylopectin content. AC fermentation of corn grits could increase the stability of paste for flour containing higher amylose content but decrease the stability of paste for flour containing high amylopectin. Specifically, CC fermentation caused significant increase in the peak viscosity value especially for corn flour of Pulut Harapan. Fermentation for up to 48 h had resulted in corn flour of Pulut Harapan variety having a higher PV value, but it did not affect the tendency to retrograde.