Production of pigments by Rhodotorula mucilaginosa

Aims@#Pigments have a large and growing market in the world. Drawbacks in their production such as raw materials availability and low productivity prompt the search for fermentation routes for industrial production. A carotenoid-producing yeast identified as Rhodotorula mucilaginosa was isolated in our laboratory. The aim of this study was to investigate the growth and carotenoid production capacity of the yeast.@*Methodology and results@#A cost-effective substrate of sago starch hydrolysate (SSH) derived from sago fiber waste was used for the fermentation. The fermentation was carried out for 96 h at 27 °C in batch mode. The biomass produced during 5 days of fermentation was 9.6 g/L, which contained a carotenoid concentration of 8.1 mg/L and a specific yield of 845.9 g/g.@*Conclusion, significance and impact of study@#The results demonstrated the capacity of R. mucilaginosa yeast to produce carotenoids and its potential for larger-scale production.

Isolation and characterisation of Arbuscular mycorrhizal (AM) fungi spores from selected plant roots and their rhizosphere soil environment

Aims@#Arbuscular mycorrhizal (AM) fungi or previously known as the vesicular-arbuscular mycorrhizal (VAM) fungi, is a type of endomycorrhiza that closely associates with most species of plants. Meanwhile, they significantly improve the nutrients uptake in exchange of photosynthates and decrease the stress caused by both biotic and abiotic factors through symbiosis relationship. However, the understanding of indigenous AM fungi species present in its host plants are comparatively inadequate, hence this research study concentrated on indigenous AM fungi population in some selected plants that contribute to agricultural sector in Malaysia and phytochemical properties of soil that affect the colonization rate of AM fungi.@*Methodology and results@#Bamboo, banana, coconut, sugarcane, papaya, lemongrass, pandan and tapioca plant were selected in this study. The soil and plant roots were sampled and the fungi spores were extracted by applying Wet sieves and decantation techniques then further purified by sucrose density centrifugation. Genera Glomus, Funneliformis, Rhizophagus, Acaulospora and Dentiscutata were isolated and Glomus was determined as the dominant genera followed by Acaulospora in these selected plants. Soil pH were found to be significantly affecting the AM fungi population and the root colonization percentage of AM fungi in the plants analysed.@*Conclusion, significance and impact of study@#From this study, tapioca recorded the highest percentage of AM fungi root colonization rate with 20.00% in root while banana recorded the lowest rate of 3.33% only. Based on this study, tapioca is recommended for the propagation of AM fungi for biofertilizer usage in agricultural sector in future.

Screening and characterisation of two Pseudomonas aeruginosa from aquaculture and water environment

Aims@#Pseudomonas has been associated with diseases occurring in people with weakened or compromised immune system after exposure to contaminated water. The diseases are commonly treated with antibiotics. However, the bacteria had developed resistances to commonly used antibiotics making treatment a difficult task. Therefore, the continuous surveillance of susceptibility of Pseudomonas especially for the human pathogen P. aeruginosa to commonly clinical and aquaculture farming used antibiotics is important to ensure that serious infections remain susceptible to those antibiotics.@*Methodology and results@#In this study, the bacteria were screened from water, sediment and fish from rivers and aquaculture farms around Kuching, Sarawak. A total number of 38 presumptive P. aeruginosa were isolated using CHROMagar TM Pseudomonas and subjected to a series of biochemical tests. Out of all the isolates tested, only two isolates designated as AS-R10(S) and BK2-OLT2(S) fulfilled the biochemical characteristics of P. aeruginosa. 16S rRNA gene sequencing further confirmed these two isolates as P. aeruginosa based on their 100% similarity with P. aeruginosa strain GD1 and P. aeruginosa strain PA1201 in NCBI database. These two isolates were tested for their susceptibilities against nine common antibiotics used in both clinical and aquaculture farming nowadays: imipenem, piperacillin, meropenem, amikacin, gentamicin, ciprofloxacin, ceftazidime, tobramycin and norfloxacin according to CLSI standard using disk diffusion method.@*Conclusion, significance and impact of study@#The two isolates exhibited total susceptibility to all the antibiotics analysed, suggesting the effectiveness of the antimicrobial agents towards P. aeruginosa isolated from aquaculture and water environment in the study area.