Diatoms are unicellular and colonial microalgae which are currently explored as one of the potential algal species for biofuel production since they are known to accumulate high lipid content under different environmental stresses. This paper focuses on the diatom Nitzschia palea subjected under various culture conditions of light intensity, temperature, and pH, using batch culture experiments for optimizing their growth, lipid content and lipid productivity. Nitzschia palea attained a maximum growth of 3.0810 6 cells/mL under the optimum conditions of 18 mmol photons m -2 s -1 light intensity, temperature of 30°C, and pH 9.The highest lipid content (1.23 mg mL -1 ) was attained at 30°C. Lipid productivity increases with increased light intensity, temperature and pH. This was positively correlated with both lipid content and culture conditions (p <0.05), while growth of N. palea was negatively correlated with lipid content (p <0.05). Nitzschia palea had shown a relatively high growth rate and lipid content which are important characteristics for consideration as a potential for biofuel resource.

Caloglossa fluviatilis is one of the least known freshwater algal species of its genus, having been reported from its type locality in Pedro Miguel, Republic of Panama, and Chalakkudy and Periyar Rivers in the State of Kerala, India. This study presents a new locality record of the species from Bataan province on the island of Luzon, Philippines. C. fluviatilis is characterised by having (1) a thallus having a width at the internode region narrower than 1.0 mm, (2) moderate development of adventitious secondary branches at the node, and (3) fewer than eight rhizoidal filaments arising from pericentral cells at the node. Indeed, this Philippine population of C. fluviatilis has helped fill the gaps and extended the distribution of the species to the western Pacific region. Further studies and reassessment of freshwater Caloglossa specimens will contribute to further understanding of these little-known genus members.

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