Judul: Survival dan pertumbuhan Cronobacter sakazakii dan Lactobacillus selama rekonstitusi susu formula
Abstrak: Cronobactersakazakii (Enterobacter sakazakii) is an emerging foodborne pathogenassociated with powdered infant formula(PIF). The bacterium has been known to cause necrotizing enterocolitis(NEC), meningitis, and sepsis in neonates, especially to those born prematurely and or with low birth weight. C.sakazakiicould be found and survive in PIFas a residual contamination during drying or filling (after pasteurization process) and reconstitution practice in household or hospitals.Recently, somePIF product is being added with Lactobacillus as probiotics, therefore the reconstitution temperature may affect both the Lactobacillus and C. sakazakii. The objectives of this study are to study (1)the influence of various temperature of the water (30, 50, and 70oC) used for reconstitution on (a) the survival and growth of C. sakazakii in PIF, (b) the survival and growth of C. sakazakii and Lactobacillus R23 present together in PIF, and (2) to determine selective enumeration media of C. sakazakii and Lactobacillus R23 when both are present in PIF. A preliminary study was conducted for rapid screening of six isolates to obtain two heat tolerant C. sakazakii isolates by using heat treatment at 54oC for 32 minutes. The main study was evaluation of survival and growth of C. sakazakii YR c3a in PIF followingreconstitution at the above temperatures in the absence or presence of Lactobacillus R23 for up to eight hours. C. sakazakii YR c3a and DES b7b were selected as the more heat tolerant. Reconstitution at 30 and 50 oC did not influence survival and growth of C. sakazakii for up to 8 h hang time.Two log reductionsof C. sakazakii occurred in PIF reconstituted with water at 70oC.At 30 oC, presence of Lactobacillus R23 in PIF also did not affect the survival and growth of C. sakazakii upon reconsitution at irrespective of the initial load ratio. Meanwhile presence of Lactobacillus did not affect C. sakazaki upon reconstitution at 50 oC when the ratio of LactobacillusR23 : C. sakazakiiYR c3a was 1:1, but growth of C. sakazakii YR c3a decreased following reconstitution when ratio of the two bacteria was 103:1.Reconstitution at 70 oC reduced the number of C. sakazakii YR c3a and DES b7b by 2.51 and 2.48 log CFU/ml, respectively. In PIF containing Lactobacillus, regardless of the ratio, Lactobacillus R23 and C. Sakazakii YR c3adecreased for up to <1,00 log CFU/ml and to 1,40 log CFU/ml, respectively. Following reconstitution at this temperature, the growth of C. sakazakiiYR c3a started tobe observed 4 h afterward while Lactobacillus R23 started to increase 2 h afterward.
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Judul: Kemampuan Campuran Bakteri Asam Laktat Kandidat Probiotik Asal Air Susu Ibu Berkompetisi dengan Cronobacter sakazakii pada Susu Formula Rekonstitusi
Abstrak: Cronobacter sakazakii is an emerging pathogen occasionally found in powdered infant formula (PIF) and causes ilnessess in certain groups of infants. To achieve the minimum risk level of C. sakazakii it is recommended to carry on reconstitution of PIF at temperature of 70 °C or more. The recommended temperature may therefore influence the presence of lactic acid bacteria (LAB) commonly added as probiotic in PIF and other milk powder. The objectives of this study were to determine the antimicrobial activities of cocktail of L. rhamnosus isolated from breast milk against C. sakazakii, to evaluate the effect of the reconstitution temperature towards the survival and growth of L. rhamnosus and C. sakazakii, and to determine the influence of L. rhamnosus on the growth of C. sakazakii after reconstitution. L. rhamnosus cocktail was more effective in inhibiting the growth of single strain C. sakazakii than cocktail of C. sakazakii. The use of cocktail of L. rhamnosus R21 & R25 could inhibit the growth of C. sakazakii YR c3a by 3.75 log CFU/mL. At the same time, the growth of cocktail of L. rhamnosus was not affected by the presence of C. sakazakii. Addition of cocktail of L. rhamnosus R21 & R25 in reconstituted powdered infant formula did not influence the growth of C. sakazakii significantly. Survival of C. sakazakii was influenced by reconstitution temperatures.
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Judul: Tree berdiameter lima adalah graceful
Abstrak: This manuscript presents some proofs that every tree of diameter five is graceful. A graceful tree is a graph which has a graceful labelling. This labelling assigns absolute difference of connected vertices, such that the resulting edge labels are mutually distinct. There are three theorems to be considered. First theorem proves that every tree of diameter four is graceful. Second theorem proves that every tree of diameter five is graceful or nearly graceful. The third theorem improves the second theorem and shows that every tree of diameter five is nearly graceful, which can be transformed into graceful using some certain patterns.
Keyword: Graf, Pelabelan graceful, Bogor Agricultural University, Institut Pertanian Bogor, IPB