Rodney Honrada Perez

Sex: Male


Kyushu University Fukuoka Japan, Doctor of Philosophy in Microbial Technology, March 2014

Kyushu University Fukuoka Japan, Master in Science in Bioscience and Biotechnology, March 2011

Visayas State University, Bachelor of Science in Food Technology, March 2004


Field of Specialization

Antimicrobial Peptides

Protein Purification

Food Preservation

Lactic Acid Bacteria


Article title: Critical fermentation factors that influence the production of multiple bacteriocins of Enterococcus faecium NKR-5-3

Authors: Rodney H. Perez, Kohei Himeno, Takeshi Zendo, Kenji Sonomoto

Publication title: Annals of Tropical Research 4(2), 2020


Bacteriocins from lactic acid bacteria (LAB) are industrially important compounds that have been utilized as a safe food preservative replacing the potentially harmful synthetic chemical preservatives, Enterococcus faecium NKR- 5-3 is a novel LAB strain that produces five different bacteriocins‘ The critical fermentation factors, such as specific medium components and optimum incubation temperature that support the maximum production of multiple bacteriocins of strain NKR-5-3, were identified. Sucrose and yeast extract were found to be the preferred carbon and nitrogen sources for bacteriocin production of this strain, respectively. The highest bacteriocin production was observed when strain NKR-5-3 was incubated at 25°C. At incubation temperatures beyond 30°C, bacteriocin production was significantly reduced and completely ceased when further raised to 40°C, These findings possess remarkable practical implications as they can be vital in the future design of a cost-effective production system for these bacteriocins. Such a system would address the issue of the high production cost, which has remained the major barrier to the development of the large-scale industrial utilization of these important compounds.

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Article title: Molecular characterization of the possible regulation of multiple bacteriocin production through a three-component regulatory system in Enterococcus faecium NKR-5-3

Authors: Naoki Ishibashi, Naho Matsumoto, Rodney Honrada Perez, Shun Iwatani, et al.

Publication title: Journal of Bioscience and Bioengineering, October 2020



Enterococcus faecium NKR-5-3 produces multiple-bacteriocins, enterocins NKR-5-3A, B, C, D, and Z (Ent53A, Ent53B, Ent53C, Ent53D, and Ent53Z). However, the biosynthetic mechanisms on how their productions are regulated are yet to be fully understood. In silico analysis revealed putative promoters and terminators in the enterocin NKR-5-3ACDZ gene cluster, and the putative direct repeats (5′-ATTTTAGGATA-3′) were conserved upstream of each promoter. Transcriptional analysis by quantitative real-time polymerase chain reaction (PCR) of the biosynthetic genes for the enterocins NKR-5-3 suggested that an inducing peptide (Ent53D) regulates the transcription of the structure genes and corresponding biosynthetic genes of enterocins NKR-5-3, except for Ent53B (a circular bacteriocin), thus consequently regulating their production. Moreover, transcriptional analysis of some knock-out mutants showed that the production of Ent53A, C, D and Z is controlled by a three-component regulatory system (TCS) consisting of Ent53D, EnkR (response regulator), and EnkK (histidine kinase). The production of the circular bacteriocin Ent53B appeared to be independent from this TCS. Nevertheless, disrupting the TCS by deletion of a single component (enkD, enkR and enkK) resulted in a slight increase of enkB transcription and consequently the production of Ent53B, presumably, as an indirect consequence of the increase of available energy to the strain NKR-5-3. Here, we demonstrate the regulatory control of the multiple bacteriocin production of strain NKR-5-3 likely through the TCS consisting of Ent53D, EnkR, and EnkK. The information of the sharing of the regulatory machinery between bacteriocins in strain NKR-5-3 can be useful in its future application such as designing strategies to effectively dispense its multiple bacteriocin arsenal.

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Article title: Processing and secretion of non-cognate bacteriocins by EnkT, an ABC transporter from a multiple-bacteriocin producer, Enterococcus faecium NKR-5-3

Authors: Hirotoshi Sushida, Miyuki Sakei, Rodney Honrada Perez, Naoki Ishibashi, et al.

Publication title: Journal of Bioscience and Bioengineering 130(6), August 2020



EnkT is an ATP-binding cassette (ABC) transporter produced by Enterococcus faecium NKR-5-3, which is responsible for the secretion of multiple bacteriocins; enterocins NKR-5-3A, C, D, and Z (Ent53A, C, D, and Z). EnkT has been shown to possess a tolerant recognition mechanism that enables it to secrete the mature Ent53C from a chimeric precursor peptide containing the leader peptide moieties that are derived from different heterologous bacteriocins. In this study, to further characterize EnkT, we aimed to investigate the capacity of EnkT to recognize, process, and secrete non-cognate bacteriocins, which belong to different subclasses of class II. For this, the non-cognate bacteriocin precursor peptides, including enterocin A, pediocin PA-1, lactococcin Q, lactococcin A, and lacticin Q were co-expressed with EnkT, and thereafter, the production of the mature forms of these non-cognate bacteriocins was assessed. Our results revealed that EnkT could potentially recognize, process, and secrete the non-cognate bacteriocins with an exception of the leaderless bacteriocin, lacticin Q. Moreover, the processing and secretion efficiencies of these heterologous non-cognate bacteriocins by EnkT were further enhanced when the leader peptide moiety was replaced with the Ent53C leader peptide (derived from a native NKR-5-3 bacteriocin). The findings of this study describe the wide substrate tolerance of this ABC transporter, EnkT, that can be exploited in the future in establishing effective bacteriocin production systems adaptive to complex fermentation conditions common in many food systems.

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Article title: Circular and Leaderless Bacteriocins: Biosynthesis, Mode of Action, Applications, and Prospects

Authors: Rodney H. Perez, Takeshi Zendo, Kenji Sonomoto

Publication title: Frontiers in Microbiology, September 2018



Bacteriocins are a huge family of ribosomally synthesized peptides known to exhibit a range of bioactivities, most predominantly antibacterial activities. Bacteriocins from lactic acid bacteria are of particular interest due to the latter’s association to food fermentation and the general notion of them to be safe. Among the family of bacteriocins, the groups known as circular bacteriocins and leaderless bacteriocins are gaining more attention due to their enormous potential for industrial application. Circular bacteriocins and leaderless bacteriocins, arguably the least understood groups of bacteriocins, possess distinctively peculiar characteristics in their structures and biosynthetic mechanisms. Circular bacteriocins have N-to-C- terminal covalent linkage forming a structurally distinct circular peptide backbone. The circular nature of their structures provides them superior stability against various stresses compared to most linear bacteriocins. The molecular mechanism of their biosynthesis, albeit has remained poorly understood, is believed to possess huge application prospects as it can serve as scaffold in bioengineering other biologically important peptides. On the other hand, while most bacteriocins are synthesized as inactive precursor peptides, which possess an N-terminal leader peptide attached to a C-terminal propeptide, leaderless bacteriocins are atypical as they do not have an N-terminal leader peptide, hence the name. Leaderless bacteriocins are active right after translation as they do not undergo any post-translational processing common to other groups of bacteriocins. This “simplicity” in the biosynthesis of leaderless bacteriocins offers a huge commercial potential as scale-up production systems are considerably easier to assemble. In this review, we summarize the current studies of both circular and leaderless bacteriocins, highlighting the progress in understanding their biosynthesis, mode of action, application and their prospects.


Article title: Mutations near the cleavage site of enterocin NKR-5-3B prepeptide reveal new insights into its biosynthesis

Authors: Rodney Honrada Perez, Haruki Sugino, Naoki Ishibashi, Takeshi Zendo, et al.

Publication title: Microbiology in Press (4), January 2017



Enterocin NKR-5-3B is a 64-residue novel circular bacteriocin synthesized from an 87-residue prepeptide. Albeit through a still unknown mechanism, the EnkB1234 biosynthetic enzyme complex processes the prepeptide to yield its mature active, circular form. To gain insights into the key region/residue that plays a role in Ent53 maturation, several mutations near the cleavage site on the precursor peptide were generated. The interaction of the precursor peptide and EnkB1234 appeared to be hydrophobic in nature. At the Leu1 position, only mutations with helix structure-promoting hydrophobic residues (Ala, Ile, Val, or Phe) were able to yield the mature Ent53B derivative. In this study, we also highlight the possible conformation-stabilizing role of the Ent53B leader peptide on the precursor peptide for its interaction with its biosynthetic enzyme complex. Any truncations of the leader peptide moiety interfered in the processing of the prepeptide. However, when propeptides of other circular bacteriocins (circularin A, leucocyclicin Q, or lactocyclicin Q) were cloned at the C-terminus of the leader peptide, EnkB1234 could not process them to yield a mature bacteriocin. Taken together, these findings offer new perspectives in our understanding of the possible molecular mechanism of the biosynthesis of this circular bacteriocin. These new perspectives will help advance our current understanding to eventually elucidate circular bacteriocin biosynthesis. Understanding the biosynthetic mechanism of circular bacteriocins will materialize their application potential.


Article title: Nutrition-adaptive control of multiple-bacteriocin production by Weissella hellenica QU 13

Authors: Yoshimitsu Masuda, Rodney Honrada Perez, Takeshi Zendo, Kenji Sonomoto

Publication title: Journal of Applied Microbiology 120(1), November 2015



Aim: To analyze nutrition-adaptive multiple-bacteriocin production by Weissella hellenica QU 13 METHODS AND RESULTS: Weissella hellenica QU 13 produces two leaderless bacteriocins, weissellicins Y and M. Their production was studied in MRS and APT media by quantification analyses with liquid chromatography mass spectrometry (LC/MS), while transcriptional analysis of biosynthetic genes was performed by real time reverse transcription (RT)-PCR. Weissellicin Y production was higher in MRS culture than in APT culture, while weissellicin M production was higher in APT culture than in MRS culture. APT medium contains a higher amount of thiamine than MRS medium, to enhance the growth of heterofermentative lactic acid bacteria. Therefore, thiamine addition to MRS culture enhanced the growth of W. hellenica QU 13; consequently, weissellicin Y production was decreased, while weissellicin M production was not affected. Furthermore, real time RT-PCR analyses indicated that the transcriptional trends of their respective structural genes, welY and welM, were different from each other, and that these two genes' transcriptions responded to nutrition conditions. Conclusion: W. hellenica QU 13 was demonstrated to control weissellicins Y and M production based on nutrition conditions. In addition, differential expression behavior of weissellicins Y and M indicates that each of them would have separate roles to adapt to different environmental situations. Significance and impact: This is the first report that describes nutrition-adaptive multiple-bacteriocin production, in which thiamine inhibits bacteriocin production while it enhances the growth of the producer strain. 

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Article title: Functional Analysis of Genes Involved in the Biosynthesis of Enterocin NKR-5-3B, a Novel Circular Bacteriocin

Authors: Rodney Honrada Perez, Naoki Ishibashi, Tomoko Inoue, Kohei Himeno, et al.

Publication title: Journal of Bacteriology, October 2015



Importance: In addition to their potential application as food preservatives, circular bacteriocins are now considered as possible alternatives to therapeutic antibiotics due to their exceptional stability conferred by their circular structure. The successful practical application of circular bacteriocins will become possible only if the molecular details of their biosynthesis are fully understood. Results of the present study offer a new perspective on the possible mechanism of circular bacteriocin biosynthesis. In addition, since some enterococcal strains are associated with pathogenicity, virulence, and drug-resistance, the establishment of the first multi-genus host heterologous production of Ent53B has a very high practical significance as it widens the area of possible Ent53B applications.


Article title: Bacteriocins from Lactic Acid Bacteria: A Review of Biosynthesis, Mode of Action, Fermentative Production, Uses, and Prospects

Authors: Rodney Honrada Perez, Maria Teresa M. Perez, Francisco B. Elgado

Publication title: International Journal of Philippine Science and Technology 8(2), 2015




Bacteriocins   are   antimicrobial   peptides   that   help   bacteria   fight   competing   bacteria   in

microecological  systems.  Bacteriocins  of  lactic  acid  bacteria  (LAB)  have  attracted  much  interest  in  recent years because of their properties that make them suitable as natural food preservatives against specific food pathogens,   and   as   possible   supplement   to   antibiotics   against   drug   resistant   bacterial   strains.   LAB bacteriocins are generally classified into the lantibiotics and non-lantibiotics, the latter divided into four sub-groups. To date, only nisin and to a lesser extent, pediocin are the commercially applied bacteriocins for food use. Clinical applications are still limited to animal health. One of the more exciting prospects on the use of

bacteriocins is the possibility of subjecting them to bioengineering to either increase antimicrobial activity or further  specify  their  target  microorganism.  The  latter  would  make  it  less  damaging  to  the  natural  gut microflora, which is a common drawback of conventional antibiotic therapy. This  paper  focuses  on  the  nature,  biology,  and  applications  of  bacteriocins  based  on  knowledge  gained abroad and in the Philippines during the last two decades


Article title: Two putatively novel bacteriocins active against Gram-negative food borne pathogens produced by Weissella hellenica BCC 7293

Authors: Weerapong Woraprayote, Laphaslada Pumpuang, Amonlaya Tosukhowong, Sittiruk Roytrakul, Rodney Honrada Perez, Takeshi Zendo, Kenji Sonomoto, Soottawat Benjakul, Wonnop Visessanguan

Publication title: Food Control 55, September 2015


Abstract: No abstract


Article title: Identification, Characterization, and Three-Dimensional Structure of the Novel Circular Bacteriocin, Enterocin NKR-5-3B, from Enterococcus faecium

Authors: Kohei Himeno, Johan Rosengren, Tomoko Inoue, Rodney Honrada Perez, et al.

Publication title: Biochemistry 54(31), July 2015



Enterocin NKR-5-3B, one of the multiple bacteriocins produced by Enterococcus faecium NKR-5-3, is a 64 aa novel circular bacteriocin that displays broad-spectrum antimicrobial activity. Here we report the identification, characterization, and three-dimensional NMR solution structure determination of enterocin NKR-5-3B. Enterocin NKR-5-3B is characterized by four helical segments that enclose a compact hydrophobic core, which together with its circular backbone, impart high stability and structural integrity. We also report the corresponding structural gene, enkB, which encodes an 87 aa precursor peptide that undergoes a yet to be described enzymatic processing that involves adjacent cleavage and ligation of Leu24 and Trp87 to yield the mature (circular) enterocin NKR-5-3B.

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Article title: Enterocin F4-9, a Novel O-Linked Glycosylated Bacteriocin

Authors: Mohamed Maky, Naoki Ishibashi, Takeshi Zendo, Rodney Honrada Perez, et al. Publication title: Applied and Environmental Microbiology 81(14), May 2015



Enterococcus faecalis F4-9 isolated from Egyptian salted-fermented fish produces a novel bacteriocin, termed enterocin F4-9. Enterocin F4-9 was purified from the culture supernatant by three steps, and its molecular mass was determined to be 5516.6 Da by mass spectrometry. Amino acid and DNA sequencing showed that the prepeptide consists of 67 amino acid residues, with a leader peptide containing a double glycine cleavage site to produce a 47-amino-acid mature peptide. Enterocin F4-9 is modified by two molecules of N-acetylglucosamine ß-O-linked to Ser37 and Thr46. The O-linked N-acetylglucosamine moieties are essential for the antimicrobial activity of enterocin F4-9. Further analysis of the enterocin F4-9 gene cluster identified enfC, which has high sequence similarity to a glycosyltransferase. The antimicrobial activity of enterocin F4-9 covered a limited range of bacteria, including, interestingly, a gram-negative strain, E. coli JM109. Enterocin F4-9 is protease-sensitive, active at a wide pH range, and moderately resistant to heat.


Article title: Purification and characterization of a novel plantaricin, KL-1Y, from Lactobacillus plantarum KL-1

Authors: Kittaporn Rumjuankiat, Rodney Honrada Perez, Pilasombut Komkhae, Suttipun Keawsompong, et al.

Publication title: World Journal of Microbiology and Biotechnology 31(6), April 2015



Three bacteriocins from Lactobacillus plantarum KL-1 were successfully purified using ammonium sulfate precipitation, cation-exchange chromatography and reverse-phase HPLC. The bacteriocin peptides KL-1X, -1Y and -1Z had molecular masses of 3053.82, 3498.16 and 3533.16 Da, respectively. All three peptides were stable at pH 2-12 and 25 °C and at high temperatures of 80 and 100 °C for 30 min and 121 °C for 15 min. However, they differed in their susceptibility to proteolytic enzymes and their inhibition spectra. KL-1Y showed broad inhibitory activities against Gram-positive and Gram-negative bacteria, including Salmonella enterica serovar Enteritidis DMST 17368, Pseudomonas aeruginosa ATCC 15442, P. aeruginosa ATCC 9027, Escherichia coli O157:H7 and E. coli ATCC 8739. KL-1X and -1Z inhibited only Gram-positive bacteria. KL-1X, KL-1Y and KL-1Z exhibited synergistic activity. The successful amino acid sequencing of KL-1Y had a hydrophobicity of approximately 30 % and no cysteine residues suggested its novelty, and it was designated "plantaricin KL-1Y". Plantaricin KL-1Y exhibited bactericidal activity against Bacillus cereus JCM 2152(T). Compared to nisin, KL-1Y displayed broad inhibitory activities of 200, 800, 1600, 800, 400 and 400 AU/mL against the growth of Bacillus coagulans JCM 2257(T), B. cereus JCM 2152(T), Listeria innocua ATCC 33090(T), Staphylococcus aureus TISTR 118, E. coli O157:H7 and E. coli ATCC 8739, respectively, whereas nisin had similar activities against only B. coagulans JCM 2257(T) and B. cereus JCM 2152(T). Therefore, the novel plantaricin KL-1Y is a promising antimicrobial substance for food safety uses in the future.


Article title: Novel bacteriocins from lactic acid bacteria (LAB): Various structures and applications

Authors: Rodney Honrada Perez, Takeshi Zendo, Kenji Sonomoto

Publication title: Microbial Cell Factories 13 (Supplement I), August 2014



Bacteriocins are heat-stable ribosomally synthesized antimicrobial peptides produced by various bacteria, including food-grade lactic acid bacteria (LAB). These antimicrobial peptides have huge potential as both food preservatives, and as next-generation antibiotics targeting the multiple-drug resistant pathogens. The increasing number of reports of new bacteriocins with unique properties indicates that there is still a lot to learn about this family of peptide antibiotics. In this review, we highlight our system of fast tracking the discovery of novel bacteriocins, belonging to different classes, and isolated from various sources. This system employs molecular mass analysis of supernatant from the candidate strain, coupled with a statistical analysis of their antimicrobial spectra that can even discriminate novel variants of known bacteriocins. This review also discusses current updates regarding the structural characterization, mode of antimicrobial action, and biosynthetic mechanisms of various novel bacteriocins. Future perspectives and potential applications of these novel bacteriocins are also discussed.


Article title: Gene Cluster Responsible for Secretion of and Immunity to Multiple Bacteriocins, the NKR-5-3 Enterocins

Authors: Naoki Ishibashi, Kohei Himeno, Yoshimitsu Masuda, Rodney Honrada Perez, et al.

Publication title: Applied and Environmental Microbiology 80(21), August 2014



Enterococcus faecium NKR-5-3, isolated from Thai fermented fish, is characterized by the unique ability to produce five bacteriocins, namely, enterocins NKR-5-3A, -B, -C, -D, and -Z (Ent53A, Ent53B, Ent53C, Ent53D, and Ent53Z). Genetic analysis with a genome library revealed that the bacteriocin structural genes (enkA [ent53A], enkC [ent53C], enkD [ent53D], and enkZ [ent53Z]) that encode these peptides (except for Ent53B) are located in close proximity to each other. This NKR-5-3ACDZ (Ent53ACDZ) enterocin gene cluster (approximately 13 kb long) includes certain bacteriocin biosynthetic genes such as an ABC transporter gene (enkT), two immunity genes (enkIaz and enkIc), a response regulator (enkR), and a histidine protein kinase (enkK). Heterologous-expression studies of enkT and ΔenkT mutant strains showed that enkT is responsible for the secretion of Ent53A, Ent53C, Ent53D, and Ent53Z, suggesting that EnkT is a wide-range ABC transporter that contributes to the effective production of these bacteriocins. In addition, EnkIaz and EnkIc were found to confer self-immunity to the respective bacteriocins. Furthermore, bacteriocin induction assays performed with the ΔenkRK mutant strain showed that EnkR and EnkK are regulatory proteins responsible for bacteriocin production and that, together with Ent53D, they constitute a three-component regulatory system. Thus, the Ent53ACDZ gene cluster is essential for the biosynthesis and regulation of NKR-5-3 enterocins, and this is, to our knowledge, the first report that demonstrates the secretion of multiple bacteriocins by an ABC transporter.

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Article title: Monitoring of the multiple bacteriocin production by Enterococcus faecium NKR-5-3 through a developed liquid chromatography and mass spectrometry-based quantification system

Authors: Rodney Honrada Perez, Kohei Himeno, Naoki Ishibashi, Yoshimitsu Masuda, et al.

Publication title: Journal of Bioscience and Bioengineering 114(5), July 2012



Enterococcus faecium NKR-5-3 produces four antimicrobial peptides referred here as enterocins NKR-5-3A, B, C and D. A two-step electrospray ionization-liquid chromatography and mass spectrometry (ESI-LC/MS)-based quantification system was developed to monitor its multiple bacteriocin production profiles, which is essential in understanding the complex production regulation mechanism of strain NKR-5-3. The developed ESI-LC/MS-based quantification system can easily monitor the multiple bacteriocin production of this strain. Using the developed system, the production of enterocin NKR-5-3B was found to be not as variable as those of the other enterocins in different cultivation media. Production of enterocin NKR-5-3B was also found to have a wider optimum incubation temperature (20-30°C) than enterocins NKR-5-3A, C and D (25°C). Furthermore, at least 2 nM of the bacteriocin-like inducing peptide, enterocin NKR-5-3D, regulated the production of NKR-5-3 enterocins except enterocin NKR-5-3B. These findings taken together suggest that enterocin NKR-5-3B has an independent production regulation mechanism from the other NKR-5-3 enterocins. The developed system could effectively pin-point the production profiles of the multiple bacteriocins of E. faecium NKR-5-3 under different fermentation conditions.

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Article title: Purification and Characterization of Multiple Bacteriocins and an Inducing Peptide Produced by Enterococcus faecium NKR-5-3 from Thai Fermented Fish

Authors: Naoki Ishibashi, Kohei Himeno, Koji Fujita, Yoshimitsu Masuda, et al.

Publication title: Bioscience Biotechnology and Biochemistry 76(5), May 2012



Enterocins NKR-5-3A, B, C, and D were purified from the culture supernatant of Enterococcus faecium NKR-5-3 and characterized. Among the four purified peptides, enterocin NKR-5-3A (5242.3 Da) was identical to brochocin A, produced by Brochothrix campestris ATCC 43754, in mature peptides, and its putative synergistic peptide, enterocin NKR-5-3Z, was found to be encoded in ent53Z downstream of ent53A, encoding enterocin NKR-5-3A. Enterocin NKR-5-3B (6316.4 Da) showed a broad antimicrobial spectrum, and enterocin NKR-5-3C (4512.8 Da) showed high activity against Listeria. Enterocin NKR-5-3D (2843.5 Da), showing high homology to an inducing peptide produced by Lactobacillus sakei 5, induced the production of the enterocins. The enterocins showed different antimicrobial spectra and intensities. E. faecium NKR-5-3 concomitantly produced enterocins NKR-5-3A, B, C, and D which probably belong to different classes of bacteriocins. Furthermore, NKR-5-3 production was induced by enterocin NKR-5-3D.


Article title: Characterization and identification of weissellicin Y and weissellicin M, novel bacteriocins produced by Weissella hellenica QU 13

Authors: Yoshimitsu Masuda, Takeshi Zendo, N. Sawa, Rodney Honrada Perez, et al.

Publication title: Journal of Applied Microbiology 112(1), January 2012



To identify and characterize novel bacteriocins from Weissella hellenica QU 13. Weissella hellenica QU 13, isolated from a barrel used to make Japanese pickles, produced two novel bacteriocins termed weissellicin Y and weissellicin M. The primary structures of weissellicins Y and M were determined, and their molecular masses were determined to be 4925·12 and 4968·40 Da, respectively. Analysis of the DNA sequence encoding the bacteriocins revealed that they were synthesized and secreted without N-terminal extensions such as leader sequences or sec signal peptides. Weissellicin M showed significantly high and characteristic homology with enterocins L50A and L50B, produced by Enterococcus faecium L50, while weissellicin Y showed no homology with any other known bacteriocins. Both bacteriocins showed broad antimicrobial spectra, with especially high antimicrobial activity against species, which contaminate pickles, such as Bacillus coagulans, and weissellicin M showed relatively higher activity than weissellicin Y. Furthermore, the stability of weissellicin M against pH and heat was distinctively higher than that of weissellicin Y. Weissella hellenica QU 13 produced two novel leaderless bacteriocins, weissellicin Y and weissellicin M, and weissellicin M exhibited remarkable potency that could be employed by pickle-producing industry. This study is the first report, which represents a complete identification and characterization of novel leaderless bacteriocins from Weissella genus.

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Article title: Production of acidophilus milk enriched with purees from colored sweet potato (Ipomea batatas Linn.) varieties

Authors: Rodney Honrada Perez and Julie Tan

Publication title: Annals of Tropical Research 28(1), January 2005



Probiotic  foods  and  drinks  are  becoming  more  popular  nowadays.  Probiotic foods are foods that contain health-promoting microorganisms. The beneficial effects of probiotics may be mediated by a direct antagonistic effect against specific groups of organisms, resulting in a decrease in their metabolism or by stimulation of immunity. Acidophilus milk enriched with purees from kinampay and RC-2000 sweetpotato

varieties was developed.

Acidophilus milk is a probiotic drink, which is a product of milk fermentation by the bacteria Lactobacillus acidophilus.The fermented milk has been reported to have therapeutic value for suppressing toxin-producing organisms in the intestine of human.

 The sugar level and product acceptability of the developed product was evaluated through sensory evaluation, and a proximate composition of the product was determined by proximate analysis. 

It was found out that at 1% and 10% levels of inocula of the starter culture, the change in Total Titratable Acidity (TTA) of acidophilus milk was the same, hence, 1% inoculum  was  found  practical  in  the  production  of  acidophilus  milk.  Findings  from previous experiments show that the maximum number of viable cells can be maintained at TTA and pH of 0.65% and 4.7 respectively (Reed, 1982). Basing on that research finding, those acidity values were used as the target optimum conditions. The optimumProduction of acidophilus milk enriched with purees from colored sweetpotato varieties incubation time was found to be at 16 hours at 37

0C for plain acidophilus milk and 14 hours for acidophilus milk enriched with

Kinampay and RC-2000 purees before incubation.

 The developed acidophilus milk was found to be more acceptable using 6.25% sugar level. 

The addition of sweet potato puree to the acidophilus milk generally improved the sensory qualities and proximate composition of the product. It reduced the moisture content and increased the ash and protein contents of the products.