Abstract. Nurhikmayani R, Daryono BS, Retnaningrum E. 2019. Isolation and molecular identification of antimicrobial-producing Lactic Acid Bacteria from chao, South Sulawesi (Indonesia) fermented fish product. Biodiversitas 20: 1063-1068. Chao is traditional fermented fish made of anchovy (Stolephorus sp.), rice, salt, and fermented naturally on controlled environment. The product comes from Pangkep Regency, South Sulawesi. Chao has the potential for the source of high-grade lactic acid bacteria isolates, especially for antimicrobial compound. Antimicrobial compound produced by lactic acid bacteria is a biopreservative compound with many advantages. The purposes of this investigation were to isolate antimicrobial-producing lactic acid bacteria from chao and to identify their isolates based on the molecular properties. Lactic acid bacteria were isolated from chao using Man Ragosa Sharpe Agar (MRSA) medium added with 0.1 % CaCO3, followed by the ability test to produce antimicrobial compound against Staphylococcus aureus FNCC 0047 as an indicator. The spectrum of crude antimicrobial as cell-free supernatant (CFS) was determined by antagonism against S. aureus FNCC 0047 and Escherichia coli FNCC 0049 on agar well diffusion test. Selected isolates of antimicrobial-producing lactic acid bacteria molecularly identified from 16S rRNA marker using primer 27F and 1492R. We obtained four isolates of lactic acid bacteria that showed the antimicrobial activity. This crude antimicrobial compound could inhibit both gram-positive Staphylococcus aureus FNCC0047 and gram-negative bacteria Escherichia coli FNCC0049. The highest crude antimicrobial activity of isolates was observed on IB1C strain. The results of molecular characterization suggested that the IB1C and IB3B strain were identified as Lactobacillus plantarum, whereas IB3E and IB3F were identified as Pediococcus pentosaceus.

Abstract. Nugroho LH, Dewatisari WF, Retnaningrum E, Purwestri YA. 2021. The potency of Sansevieria trifasciata and S. cylindrica leaves extracts as an antibacterial against Pseudomonas aeruginosa. Biodiversitas 22: 408-415. Sansevieria trifasciata and Sansevieria cylindrica are the major herbs in Indonesia, which contain several bioactive compounds as potential sources of antibacterial agents. This study aims to evaluate the antibacterial activity of S. trifasciata and S. cylindrica leaves extract and fraction against Pseudomonas aeruginosa and to identify its bioactive compounds. Crude ethanolic extract of S. trifasciata and S. cylindrica leaves were tested for their antimicrobial activity by disk diffusion method against P. aeruginosa. S. trifasciata showed strong antibacterial activity with an inhibition zone of 18.3 mm compared to S. cylindrica. Different concentrations of extract i.e. 4 mg/mL, 8 mg/mL, 16 mg/mL, 32 mg/mL, 64 mg/mL, 128 mg/mL and 256 mg/mL were tested for their minimum inhibitory concentrations (MIC). The MIC results showed that the S. trifasciata extract was able to inhibit bacterial growth at a concentration of 32 mg/mL. Results of vacuum liquid chromatography (VLC) and thin-layer chromatography (TLC) revealed that only fraction 3 showed the highest antibacterial activity at 16 mg/mL. In TLC bioautography analysis, fraction 3 showed a clear zone at Rf 0.93. The phytochemical analysis showed that terpenoid, phenolic, triterpenoid, and flavonoid compounds were found in S. trifasciata extract that were associated with antibacterial activity.

Abstract. Retnaningrum E, Yossi T, Nur'azizah R, Sapalina F, Kulla PDK. 2020. Characterization of a bacteriocin as biopreservative synthesized by indigenous lactic acid bacteria from dadih soya traditional product used in West Sumatra, Indonesia. Biodiversitas 21: 4192-4198. A total of 4 isolates of lactic acid bacteria (strain BDL08, BDL11, BDL12, and BDL13) isolated from dadih soya were investigated for the ability to produce bacteriocin based on their antibacterial activities against Listeria monocytogenes ATCC 7644. Based on comparative 16S rDNA sequencing analysis, isolates BDL 11, BDL12, and BDL13 were identified as Lactobacillus plantarum while the isolates BDL 08 was identified as Leuconostoc mesenteroides. All crude bacteriocins producing strains revealed broad antibacterial spectrum against 7 different indicator bacteria, including Gram-positive and Gram-negative bacteria. L. plantarum BDL11 displayed the highest bacteriocin activity relative to others. The bacteriocin produced by the strain was not affected by pH, heating, and NaCl concentration but was sensitive to proteolytic enzymes. This research indicated that the bacteriocin in the food industry has the potential to be used as a biopreservative.

ABSTRACT

Background and Aim: Extended-spectrum β-lactamase (ESBL) is an enzyme produced by the family of Enterobacteriaceae, especially Escherichia coli and Klebsiella pneumoniae, which can hydrolyze β-lactam antibiotics, such as penicillins, cephalosporins, cephamycin, and carbapenem. ESBL-producing bacteria are widely distributed from farms to slaughterhouses until food products originating from animals are available in the market, which plays an important role as a pathway for the exposure and transmission of ESBL-producing bacteria from food products of animal origin to humans. This study aimed to determine the antibacterial activity of Syzygium aromaticum (clove) and Cinnamomum verum (cinnamon) essential oils against strains resistant to ESBL-producing E. coli and K. pneumoniae isolates. Materials and Methods: The antibacterial activity of clove and cinnamon essential oils was tested against three strains of tested bacteria using the disk diffusion method. The minimum inhibitory concentration (MIC) of clove and cinnamon essential oils was determined using the broth microdilution method. The minimum bactericidal concentration (MBC) was determined using the MIC. Morphological changes on each tested bacteria were observed through scanning electron microscopy (SEM). Results: Both essential oils exhibited inhibitory effects toward all test organisms, indicated by inhibition zones around the disk. The MIC values of clove essential oil were 0.078% (v/v) for all tested bacteria, whereas the MICs of cinnamon essential oil ranged from 0.039% (v/v) to 0.156% (v/v) for all tested bacteria. MBC values of clove and cinnamon essential oils ranged from 0.078% (v/v) to 0.156% (v/v) for all tested bacteria. There were morphological changes in each tested bacterial cell that was observed through SEM. Each tested bacteria treated with clove and cinnamon essential oils showed shrinkage and cells lysis. Conclusion: It was concluded that clove and cinnamon essential oils have emerged as effective antibacterial agents by showing high antibacterial activity against ESBL-producing E. coli and K. pneumoniae isolates, as evidenced by the inhibition zone diameter and MIC value.