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Background: The use of single cell protein (SCP) has become a method for alleviating the shortage of protein feed that microorganisms propagate in a suitable culture medium. In this study, SCP was produced by yeast to use the nutrition contained in the biogas slurry of chicken manure. Results: The results showed that Galactomyces candidum was the most efficient at producing SCP among the seven yeasts studied. The maximum cell dry weight (CDW) 6.79 g/L and protein content 39.39%, were obtained under the fermentation conditions of initial NH4+-N concentration of 2000 mg/L and a C/N ratio of 6:1 with acetate as the pH regulator. The total CDW increased to 9.24 g/L after secondary fermentation. Metal elements had a little effect on the growth of G. candidum. The addition of sulfur not only promoted the synthesis of sulfur-containing amino acid cysteine but also increased protein content by promoting the synthesis of glutamic acid and glutamine. Conclusions: Future experiments should focus more on achieving high-density cultivation and more efficient utilization of ammonia nitrogen in the biogas slurry.How to cite: Zhou Pan, Zhang Lu, Ding Hongxia, et al. Optimization of culture conditions of screened Galactomyces candidum for the production of single cell protein from biogas slurry. Electron J Biotechnol 2021;55. https://doi.org/10.1016/j.ejbt.2021.11.006

Potato (Solanum tuberosum L.) is an important crop throughout the world. An uncharacterized disease has been observed on potato plants during the growing season and tubers during the storage period from Nileke County, Qitai County and other locations in Xinjiang, China. A particular fungus was consistently isolated from the infected potato plants and tubers. Based on its morphology, molecular characteristics, pathogenicity test and internal transcribed spacer (ITS) sequence, the pathogens was identified as Galactomyces candidum F12. Further study also showed that the hyphae and conidia of the pathogenic fungus grew faster as the temperature was 30°C, pH was 7, soluble starch was used as optimal carbon source and yeast powder as optimal nitrogen source. In addition, 12-h continuous illumination light was beneficial to the hyphal growth, while 24-h continuous illumination was beneficial to the sporulation of the strain at 30°C. To our knowledge, this is the first report of Galactomyces candidum causing leaf wilt and postharvest tuber rot on potato in China.

Four inulinolytic yeast isolates were isolated and identified by molecular methods. They were belonged to Candida catenulata, Sarocladium kiliense, Galactomyces candidum and Scopulariopsis brevicaulis. The production of inulinase by the previous isolates through, 72h was done on two media using jerusalem artichoke tubers, garlic bulbs, dahlia tubers and chicory roots as natural sources of inulin. The highest values of the produced inulinase were obtained on Bharathi et al. (2011) medium after 48h of incubation. Jerusalem artichoke proved to be the best inulin source for enzyme production by Scopulariopsis brevicaulis (38.22 µg/ml), followed by dahlia (32.45 µg/ml). The best substrate for inulinase production by Sarocladium kiliense was dahlia (29.21 µg/ml) followed by garlic (28.65 µg/ml). As for Galactomyces candidum the maximum enzyme production was obtained using jerusalem artichoke (34.96 µg/ml) followed by garlic (31.84 µg/ml). The best material for inulinase production by Candida catenulate (34.15 µg/ml) was dahlia, followed by garlic (31.40 µg/ml). It can be concluded that inulin containing plant materials could be employed as a carbon source for inulinase production, it offer advantage in comparison to purified substrate because it have low cost and high productivity.

The potential of protoplast fusants of Wickerhamomyces anomalus and Galactomyces candidum isolates for ethanol production from cassava starch was evaluated. The protoplasts were obtained from 18 h ...

Gioddu is the sole variety of fermented milk originating in Italy. Despite the long history of consumption, Gioddu still represents an undisclosed source of microbial diversity. The present study was aimed to get an insight into the bacterial and fungal diversity of Gioddu samples collected from two artisan producers located in Sardinia. To this end 3 batches of Gioddu were collected from each producer and subjected to Polymerase Chain Reaction–Denaturing Gradient Gel Electrophoresis (PCR-DGGE) analyses. Gioddu was produced with sheep milk in accordance with the local tradition. Regarding the bacterial population, a low biodiversity emerged. In more detail, the sole species Lactobacillus delbrueckii subsp. bulgaricus was detected in all the samples, irrespective of the producer or the batch. A more ample microbial diversity was highlighted for the fungal population that included closest relatives to Pichia cactophila, Kluyveromyces marxianus and Galactomyces candidum. Based on the results, the detected bacterial and fungal species generally clustered in accordance with the producer, irrespective of the batch considered. It is noteworthy that, Gioddu revealed several microbiological similarities with kefir beverage, thus suggesting, by analogy, potential health benefits related to its consumption. More research is needed to better clarify the microbiota composition of Gioddu by using more powerful metagenomic techniques.

Gioddu, also known as “Miciuratu”, “Mezzoraddu” or “Latte ischidu” (literally meaning acidulous milk), is the sole variety of traditional Italian fermented milk. The aim of the present study was to elucidate the microbiota and the mycobiota occurring in artisan Gioddu sampled from three Sardinian producers by combining the results of viable counting on selective culture media and high-throughput sequencing. Physico-chemical parameters were also measured. The overall low pH values (3.80–4.22) recorded in the analyzed Gioddu samples attested the strong acidifying activity carried out by lactic acid bacteria during fermentation. Viable counts revealed the presence of presumptive lactococci, presumptive lactobacilli and non-Saccharomyces yeasts. A complex (kefir-like) microbiota of bacteria and yeasts was unveiled through sequencing. In more detail, Lactobacillus delbrueckii was found to dominate in Gioddu together with Streptococcus thermophilus, thus suggesting the establishment of a yogurt-like protocooperation. Unexpectedly, in all the three analyzed batches from two out of the three producers Lactobacillus kefiri was also detected, thus representing an absolute novelty, which suggests the presence of bioactive compounds (e.g. exopolysaccharides) similar to those characterizing milk kefir beverage. Mycobiota population, studied for the very first time in Gioddu, revealed a more complex composition, with Kluyveromyces marxianus, Galactomyces candidum and Geotrichum galactomyces constituting the core species. Further research is needed to disclose the eventual occurence in Gioddu of probiotic cultures and bioactive compounds (e.g. exopolysaccharides, angiotensin-converting enzyme inhibitory peptides and antimicrobial compounds) with potential health-benefits for the consumers.

Bacteria generally ferment milk but, sometimes, yeasts are found in fermented milks. The presence of these yeasts in the microbial community of some fermented milks could be intentional or accidental. The Diversity of yeasts in the products was investigated using a molecular technique employing variable regions of 26S rDNA profiles generated by PCR-DGGE (Polymerase Chain Reaction-Denaturing Gradient Gel Electrophoresis). Two types of samples: artisanal or handcraft yoghurt and traditionally fermented milks were collected in three towns of the three regions of the northern part of Cameroon. Firstly, a comparison was made between the 16 traditionally fermented milks collected in Maroua, Garoua and Ngaoundre each of the 3 regions. Secondly, it was between 26 artisanal fermented milks of each region and finally, between the two types of products. The different PCR-DGGE 26S rDNA profiles obtained were analyzed and DNA sequencing was used to compare yeasts from each method of production. Twelve (12) species of Yeasts were identified as: Malassezia globosa, Hanseniaspora uvarum, Galactomyces candidum, Candida tropicalis, Aureobasidium pullulans, Torulaspora globosa, Saccharomyces cerevisiae/paradoxus, Pichia kluyveri, Candida parapsilosis, Torulaspora delbrueckii, Kluyveromyces marxianus, Candida orthopsilosis and Pseudozyma sp. Yeast diversity was higher for artisanal fermented milks (yoghurt) with at least 10 species, while for traditionally non packed fermented milks only 5 species were identified with a predominance strain of Galactomyces candidum, Candida parapsilosis, Torulaspora delbrueckii, Saccharomyces cerevisiae/paradoxus and Kluyveromyces marxianus. The different species of yeast might be introduced accidentally in artisanal yoghurt; however, for traditionally fermented milks their presence might be associated to the starter. Keywords: Fermented milk, Yeasts, Artisanal yoghurt, PCR-DGGE, Cameroon

A strain of bacteria that demonstrated efficient nitrogen removal potential under low C:N conditions was screened from landfill leachate. The strain was identified as Galactomyces candidum by ITS sequencing, and growth density and removal of ammonia nitrogen were assessed after 24 h of incubation. The results showed that the optimum ammonia nitrogen reduction conditions for G. candidum was at pH 8.0 and 30 °C, with a C:N ratio of 1.5:1; the highest rate of ammonia nitrogen removal was 93.1%. This novel function of G. candidum offers great potential in the removal of ammonia nitrogen from sewage, especially in low C:N wastewater. Our study provides a new theoretical basis for the industrial application of bacteria in the biochemical treatment of wastewater and reduces environmental pollution.A novel function and potential of Galamyces candidum in the removal of ammonia nitrogen from wastewater treatment was found, which provides a theoretical basis for the treatment of ammonia in wastewater.

Long-chain alkylphenols including octylphenol (OP) are well-known toxic pollutants prevailing in the environment due to the massive demand of these chemicals in industry and have been identified as endocrine disrupting chemicals (EDCs). While a considerable amount of work has addressed the degradation capacity of EDCs carried out by bacterial and filamentous fungal strains, little is known about the EDC degradation by yeasts. In this study, we isolated three branched-chain OP-degrading yeast strains from samples collected from a wastewater treatment plant in Taipei, Taiwan, by enrichment methods using 4-t-octylphenol (4-t-OP) as the sole carbon and energy source. Analysis of ITS and LSU rDNA gene sequences revealed that these isolates belonged to two genera and were designated as Candida rugopelliculosa RRKY5, Galactomyces candidum RRK17 and G. candidum RRK22. Growth properties of the isolates were explored using different substrates such as 4-t-OP, 4-t-nonylphenol (4-t-NP), octylphenol polyethoxylates (OPEOn), nonylphenol polyethoxylates (NPEOn), phenol and isooctane. Of these three, the strain RRKY5 utilized a wide variety of substrates and grew faster than the others. Results of HPLC analysis indicated that 4-t-OP degradation took place both in the presence and absence of the co-substrate dextrose (0.05%): within 24 days, 93% or 95% of 4-t-OP was degraded by C. rugopelliculosa RRKY5 in media with or without dextrose, whereas degradation was lower (less than 75%) in the two strains of G. candidum. Therefore, in contrast to the 4-t-OP degradation by filamentous ligninolytic fungi, dextrose did not appear to exert a significant impact on this process in yeast cultures. It can be concluded that RRKY5 is a potent candidate for the biodegradation of 4-t-OP and thus can potentially be used for bio-remedial actions in the future. To our knowledge, this is the first evidence demonstrating that pure cultures of yeast strains are capable of utilizing branched-chain OP.

This study was done to recover fungi associated with postharvest rotting of bitter yam, Dioscorea dumentorum tubers in Nsukka Agroecological Zone, Nigeria. Tubers showing signs of rot were picked from farmers in four randomly selected towns in the zone. The towns included, Nsukka, Orba, Ibagwa and Obollo-Afor. Five (5) samples each were picked from three (3) randomly selected farmers. Samples were packaged in sterile polythene bags, labeled accordingly and moved to the laboratory for studies. The fungal isolates were identified using both cultural and molecular techniques. Results showed that mycoflora of rotted bitter yams in the Zone were, Aspergillus flavus , Aspergillus niger , Lasiodiplodia pseudotheobromae , Galactomyces candidum and Rhizopus delemar . The percentage frequencies of occurrence of the fungal organisms ranged from 14.03% to 26% with A. niger recording the highest (26%) while A. flavus recorded the least (14.03%). Pathogenicity tests revealed that the fungi produced rots (diameter) ranging from 1.70 cm to 2.40 cm with R. delemar recording the highest rot diameter (2.40 cm) while A. niger produced the least (1.70 cm) Keywords: Bitter yam, mycoflora, postharvest, fungal organisms, Nsukka, rots