Plant growth promoting rhizobacteria (PGPR) (e.g., Azospirillum and Bacillus spp.) have been reported to enhance growth and fix N2 with several nonleguminous crops. These rhizobacteria have the potential to be applied to oil palm seedlings and, consequently, reduce the cost of nitrogenous fertilizer. The rhizobacteria are also known as a bioenhancer for the ability to increase root growth and enhanced water and nutrient absorption by the host plants.An experiment was carried out in the field nursery station, Federal Land Development Authorities (FELDA), Bukit Mendi, Pahang, Malaysia, to observe the effects of PGPR inoculation on enhanced nutrient accumulation and plant growth (tops and roots) of oil palm seedlings under field nursery conditions. The inoculation process showed positive response in enhancing higher accumulation of nitrogen (N), phosphorus (P), and potassium (K) in the plant tissues, enhanced root dry weight and top growth (dry matter and leaf chlorophyll content) of the host plants under field nursery conditions.
Aims: Halophilic micro-organisms have received much interest because of their potential biotechnological applications, among which is the capability of some strains to synthesize polyhydroxyalkanoates (PHA). Halomonas sp. SK5, which was isolated from hypersaline microbial mats, accumulated intracellular granules of poly(3-hydroxybutyrate) [P(3HB)] in modified accumulation medium supplemented with 10% (w/v) salinity and 3% (w/v) glucose. Methods and Results: A cell density of approximately 3Á0 g l À1 was attained in this culture which yielded 48 wt% P(3HB). The bacterial strain was also capable of synthesizing poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV)] when cofed with relevant precursors. Feeding with sodium valerate (0Á7 mol l À1 carbon) at various time intervals within 36 h resulted in 3HV molar fractions ranging from 6 up to 54 mol%. Oil palm trunk sap (OPTS) and seawater as the carbon source and culture medium respectively facilitated a significant accumulation of P(3HB). Simplified downstream processing based on osmotic lysis in the presence of alkali/detergent for both dry and wet biomass resulted in approximately 90-100% recovery of polymers with purity as high as 90%. Weight-average molecular weight (M w ) of the polymers recovered was in the range of 1-2 9 10 6 . Conclusions: Halomonas sp. SK5 was able to synthesize P(3HB) homopolymer as well as P(3HB-co-3HV) copolymer from various carbon sources. Significance and Impact of the Study: This is the first time a comprehensive study of both production and downstream processing is reported for Halomonas spp.
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