Indonesia is a mega biodiversity country with various local wisdom, including the enormous variety of fermented foods and beverages. Indonesian researchers have conducted an intensive study to understand the diversity of microbes on those fermented products, one of which shows probiotic properties. Compared to that lactic acid bacteria, the study on probiotic yeasts is less explored. Probiotic yeast isolates are commonly isolated from traditional Indonesian fermented products. Saccharomyces, Pichia, and Candida are among Indonesia's most popular genera of probiotic yeasts, primarily applied in poultry and human health. The exploration of functional probiotic characteristics, such as antimicrobial, antifungal, antioxidant, and immunomodulator, has been widely reported from these local probiotic yeast strains. In vivo studies in a model organism such as mice conclude the prospective functional probiotic characteristics of the yeast isolates. Employment of current technology, such as omics, is essential in elucidating those functional properties. Advanced research and development of probiotic yeasts in Indonesia are gaining significant attention currently. For instance, probiotic yeasts-mediated fermentation in the production of kefir and kombucha are among the trend with promising economic value. The future trends of probiotic yeasts research in Indonesia are discussed in this review to give valuable sight into the application of indigenous probiotic yeasts in various fields.

Abstract. Wulan R, Astuti RI, Rukayadi Y, Meryandini A. 2021. Evaluation of Indigenous Pichia kudriavzevii from cocoa fermentation for a probiotic candidate. Biodiversitas 22: 1317-1325. Currently, probiotics are becoming a concern along with a healthy lifestyle awareness. Besides bacteria, yeast can be used as a probiotic candidate with specific functional properties. Research on yeast as a probiotic is still limited (except for Saccharomyces boulardii). Previous research has isolated yeasts from the cocoa fermentation process. This study aimed to evaluate the probiotics properties and antioxidant activity of yeast strains isolated from spontaneous cocoa fermentation in Sukabumi, Indonesia. Previous research has isolated 23 yeast strains from spontaneous cocoa (Theobroma cacao L.) fermentation. Of the 23 yeast strains isolated from cocoa fermentation, 22 strains showed negative hemolysis as an indicator of non-pathogenic properties. Ten yeast strains were able to grow at 37 °C and 41 °C, pH 3, 0.5% bile salts, had autoaggregation ability (63.99-95.33%), and co-aggregation with S. typhimurium ATCC14028 (>80%), as character requirement for probiotic candidates. The genetic identification of the ten yeast strains showed that they were 99% identical to Pichia kudriavzevii. Based on its antioxidant activity, the P. kudriavzevii 2P10 metabolites had the highest percentage of inhibition (68.51%) against DPPH free radicals and resistance to H2O2 oxidative stress up to 3 mM. It can be concluded that P. kudriavzevii 2P10 is a promising probiotic candidate for functional foods and health purposes.

Fermentation of Lactic Acid Bacteria (LAB) Pediococcus pentosaceus can improve the quality of food and its shelf life. Using commercial LAB specific media, de Man Rogosa and Sharpe (MRS) for growth on industrial scale application is not efficient. Tapioca wastewater (TW) still contains some of the nutrients needed for the growth of P. pentosaceus, but needs the enrichment of carbon sources (5% of glucose) and nitrogen sources (ammonium sulfate). This study aimed to use tapioca industrial wastewater with the addition of glucose and ammonium sulfate as an alternative growth media for lactic acid bacteria P. pentosaceus E.1222. The results showed that glucose and nitrogen had no significant effect on the number of bacterial colonies. The highest substrate efficiency was tapioca wastewater (86.81%), MRS broth (53.73%), and TW with 5% of glucose and 1% of ammonium sulfate (43.53%) respectively. Maximum growth rate (μmaks) was found in TW with 5% of glucose and 1% of ammonium sulfate (0,52 hours-1). Increasing the starter volume until 1000 mL in TW with 5% of glucose and 1% of ammonium sulfate showed a slight decrease in the log number of bacteria from 8,836 (50 mL), 8,401 (500 mL), to 8,063 (1000 mL).

As the world's largest producer of crude palm oil, Indonesia also produces high palm kernel cake (PKC) by-products. PKC has a high mannan content, so it can be used to produce prebiotic mannan-oligosaccharides (MOS). Enzymatic MOS production can be carried out using actinobacterial mannanase's microbiological approach. The HJ45B-1 isolate was the best isolate, with a peak enzyme production of 0,338 U/mL on the 10th day of incubation. The mannanase enzyme was stable in storage at 27°C. MOS production using 1% PKC substrate produced MOS with the best degree of polymerization (2-4) with incubation for 1-3 hours. Morphological characteristics and molecular identification based on the 16S rRNA gene indicated that the HJ45B-1 isolate was Streptomyces spp.   Keywords: actinobacteria, mannanase, mannan-oligosaccharides, palm kernel cake, Streptomyces