Maximum Cell Density Research Articles

Variation in the growth and toxin production of Gymnodinium catenatum under different laboratory conditions

The chain-forming dinoflagellate Gymnodinium catenatum is the only known gymnodinioid dinoflagellate that produces paralytic shellfish toxins (PST). Dense blooms caused by the dinoflagellate have been frequently reported in coastal waters of Fujian, China since 2017. While there is still limited understanding of the major physiological characteristics of G. catenatum isolated from Fujian coastal waters, the growth and toxin production of the G. catenatum strain were examined in batch cultures with different levels of irradiance, temperature, salinity, nitrate, and phosphate conditions. The results indicated that the highest maximum cell density of the strain was achieved at 70 µmol m−2 s−1, with the highest growth rate at 120 µmol m−2 s−1. The strain grew well within the temperature range of 15–30 °C, with maximum growth rate and cell density achieved at 20 °C. The dinoflagellate also showed higher tolerance to salinity variation (20–40), with the highest growth rate at salinity 25. Meanwhile, G. catenatum showed higher demand for nitrogen and phosphorus as indicated by its higher half-saturation constant. A decrease in nitrate and phosphate greatly inhibited the growth of G. catenatum. The toxin profile of the G. catenatum strain was conservative and dominated mainly by the N-sulfcarbamoyl C-toxins (> 95%), indicating its hypotoxicity. The cellular toxicity increased with the algal growth, with the highest cellular toxicity observed at the stationary growth phase. The cellular toxicity of G. catenatum also responded to environmental variations including lower temperature (15 °C), lower salinity (20), nitrate-repletion, and phosphate-depletion conditions which enhanced the cellular toxicity, while irradiance exerted non-significant influence. The present study depicted the physiological characteristics of the particular G. catenatum strain and provided valuable insight on the ecophysiology of G. catenatum in natural coastal waters.

Roles and interactions of the specialized initiation factors EIF4E2, EIF4E5, and EIF4E6 in Trypanosoma brucei: EIF4E2 maintains the abundances of S-phase mRNAs.

Trypanosoma brucei has six versions of the cap-binding translation initiation factor EIF4E. We investigated the functions of EIF4E2, EIF4E3, EIF4E5, and EIF4E6 in bloodstream forms. We confirmed the protein associations previously found in procyclic forms and detected specific copurification of some RNA-binding proteins. Bloodstream forms lacking EIF4E5 grew normally and differentiated to replication-incompetent procyclic forms. Depletion of EIF4E6 inhibited bloodstream-form trypanosome growth and translation. EIF4E2 copurified only the putative RNA-binding protein SLBP2. Bloodstream forms lacking EIF4E2 multiplied slowly, had a low maximal cell density, and expressed the stumpy-form marker PAD1 but showed no evidence for enhanced stumpy-form signaling. EIF4E2 knock-out cells differentiated readily to replication-competent procyclic forms. EIF4E2 was strongly associated with a subset of mRNAs that are maximally abundant in the S-phase, and these all had decreased abundances in EIF4E2 knock-out cells. Three EIF4E2 target mRNAs are also bound and stabilized by the Pumilio domain protein PUF9. Yeast 2-hybrid results suggested that PUF9 interacts directly with SLBP2, but PUF9 was not detected in EIF4E2 pull-downs. We speculate that the EIF4E2-SLBP2 complex might interact with its target mRNAs, perhaps via PUF9, only early during G1/S, stabilizing the mRNAs in preparation for translation later in S-phase or in early G2.

Retinal ganglion cell topography and spatial resolution in the smelt Hypomesus japonicus (Brevoort, 1856)

AbstractThe present study deals with the topography of retinal ganglion cells (GCs) and spatial resolution in the smelt Hypomesus japonicus. The eyes and retinae were examined by light microscopy and computerized tomography. DAPI labelling was used to visualize cell nuclei in the ganglion cell and inner plexiform layers. Two zones of increased GC density in the nasal and temporal retina were bridged by a horizontal streak with the GC density ranging from 5600 to 8000 cells/mm2. The maximum cell density (area retinae temporalis) ranged from 9492 to 14,112 cells/mm2, and the total number of GCs varied from 286 x 103 to 326 x 103 cells in three individuals. The theoretical anatomical spatial resolution (the anatomical estimate of the upper limit of visual acuity) was minimum in the ventral periphery (smaller fish, 1.43 cpd; larger fish, 1.37 cpd) and maximum in area retinae temporalis (smaller fish, 2.83 cpd; larger fish, 2.41 cpd). The relatively high density of GCs and presence of the horizontal streak and area retinae temporalis in the H. japonicus are consistent with its highly visual behaviour. The present findings contribute to better understanding of the factors affecting the topography of retinal ganglion cells and mechanisms of visual adaptation in fish.

Effects of Salinity on Growth and In Vitro Ichthyotoxicity of Three Strains of Karenia mikimotoi

Karenia mikimotoi is one of the most damaging ichthyotoxic dinoflagellate species commonly found in China. However, its growth and ichthyotoxicity responses to salinity changes are still largely unknown. In this study, the growth and ichthyotoxicity of three K. mikimotoi strains, Hong Kong strain KMHK, Japanese strain NIES2411 and New Zealand strain CAWD133, under different salinities (25 to 35 ppt), initial algal densities (5 to 40 thousand cells) and growth phases were investigated. Results indicated that the optimum salinity for all three strains was 30 ppt. The Japanese strain achieved the highest maximum cell densities (cells mL−1) and the New Zealand strain achieved the highest specific growth rate. The Hong Kong and New Zealand strains could not tolerate the low salinity at 25 ppt and the algal cells burst after 3 days of exposure. The average cell widths of all three algal strains in 35 ppt salinity were significantly larger than that in 30 ppt. The acute toxicity test performed on Oncorhynchus mykiss gill cell line RTgill-W1 revealed that the median lethal times for KMHK and NIES2411 were 66.9 and 31.3 min, respectively, and their ichthyotoxicity was significantly affected by algal cell density and growth phase. Nevertheless, CAWD133 did not pose any ichthyotoxicity. The gill cell viability levels at 30 min were reduced from 96 to 61% and 95 to 39% for KMHK and NIES2411, respectively, when the algal cell density increased from 5 × 103 to 4 × 104 algal cells mL−1. Both KMHK and NIES2411 at stationary phase also had higher toxicity than at log phase, with a 27% reduction of gill cell viability, and exerted higher toxicity to the gill cells under extremely low (28 ppt) or high (35 ppt) salinity. These findings demonstrated that the growth–ichthyotoxicity response of Karenia mikimotoi to salinity was not only strain-specific but also depended on its density and growth phase. Study on the effects of salinity on the growth and toxicity of K. mikimotoi is greatly limited. Results from the present study provide valuable insight on the growth and toxicity of different K. mikimotoi strains, which is important in understanding their occurrence of algal bloom and fish-killing action.

Isolation, Identification, Optimization of Baker’s Yeast from Natural Sources, Scale-Up Production Using Molasses as a Cheap Carbohydrate Source, and Evaluation for Bread Production

(1) Background: Bangladesh must has to spend a large amount of foreign currency to import commercial baker’s yeast every year. We could save money by finding a potential Saccharomyces cerevisiae from natural sources compatible with commercial baker’s yeast production. (2) Methods: Grapes, rice, pineapples were collected, processed, and inoculated on YMA plates and incubated at 30 °C for 48 h. Then 11 single morphologically well-formed colonies were isolated, purified, and identified, three as S. cerevisiae, three as S. rouxii, three as S. bisporus, and two as S. exigus based on standard cultural, morphological, and biochemical characteristics. Identified S. cerevisiae (designated as G2, P5 and R3) were then assessed for CO2 production as a measure of their baking potential during bread production and compared with two commercial strains (designated as C1 and C2). (3) Results: Isolate-G2 produced the maximum of 1830 mm3 of gas, whereas C1, C2, R3, and P5 produced 1520, 1680, 770, and 610 mm3 gas, respectively. No strain produced H2S which is associated with an off-flavor and unpleasant taste. These isolates showed maximum cell density at a pH range of 4–5.5 in 4–16% molasses broth at 30 °C after 4 days of incubation and maximum 4.75 × 109, 7.9 × 108, 1.472 × 1010, 2.08 × 1010 and 5.24 × 109 CFU mL−1 were produced by C1, C2, G2, P5 and R3, respectively. Isolate-G2 was found to have the most potential, whereas isolate-R3 and P5 have satisfactory potential. (4) Conclusions: G2 could be a good candidate for commercial trials.

Bacterial exudates as growth‐promoting agents for the cultivation of commercially relevant marine microalgal strains

AbstractIn laboratory and industrial cultivation of marine microalgae, it is customary to enrich cultures with macronutrients (N, P), chelated trace metals, and vitamins at ~104× concentrations found in nature to obtain high culture densities. Other naturally occurring growth‐promoting compounds found in local seawater are not enriched and remain at environmental concentrations. Microalgae may thus be deprived of the mutualistic contributions of co‐occurring microorganisms with which they have evolved complex chemical relationships. In the present study, we assess the direct (mixed bacteria–microalgae cultivation) and indirect (exposure to exudates only, without physical contact) effects of 10 bacterial strains on the growth of five marine microalgal strains used as feeds in marine aquaculture hatcheries. Bacterial strains were selected based upon previously reported growth‐promoting characteristics in plants or microalgae, or known release of probiotics. Our experiments demonstrate superior stimulation of microalgal growth by bacterial exudates, and without the presence of the bacteria that produced these exudates. However, response to bacterial exudate enrichment was dependent upon the microalgae strain and bacterial pairing. Exudates fromBacillus,Mesorhizobium, andPhaeobacterstrains were most effective, with 22%–69% increases in microalgal specific growth rate. Such findings indicate that bacterial exudates accelerate rate‐limiting processes governing nutrient acquisition, assimilation, or anabolism, and possibly algal release of exopolymeric substances. Maximal cell density, however, remained constrained by macronutrient limitation. Scaled‐up trials in an oyster hatchery confirmed the practical benefit of bacterial exudate culture medium enrichment and demonstrated the suitability of exudate‐enriched microalgae to feed hatchery‐reared bay scallops. This work presents a promising strategy to improve microalgal culture media formulations using bacterial exudate components as growth promoters, and is the first such study to identify specific pairings with relevance for aquaculture production.

Characterization of Pseudoalteromonas sp. from Aquaculture Environment and Optimization of Fermentation Culture Parameters by RSM-Based Modeling

The aim of the study was to identify Pseudoalteromonas strain OS-9 and evaluate its anti-Vibrio potential. Based on the morphological, biochemical, and 16S rRNA sequence analysis, the strain was identified as Pseudoalteromonas haloplanktis. Experiments designed with Box Behnken showed that cell density and cell-free supernatant activity were simultaneously maximum at 30°C, pH 7, and 90 h. The coefficient values obtained from the response surface methodology regression equations determined that pH was more effective on responses than other physical variables. The cell-free supernatant of P. haloplanktis OS-9 extracted under optimized conditions was only effective on Gram-negative fish pathogenic bacteria and especially on Vibrio. Among Vibrio spp., the strongest inhibitory effect was observed against V. rotiferianus. At the maximum cell density (10.48 OD), the strain OS-9 showed the maximum inhibitory effect against V. rotiferianus (26.42 mm zone diameter). In co-culture assay, the growth of V. rotiferianus was inhibited after 96 h with an initial level of 1.0 × 106 CFU ml-1 by the strain OS-9. These results indicated that P. haloplanktis strain OS-9 could be considered as a potential Vibrio bio-controlling agent.

Establishment of ultrasonic stimulation to enhance growth of Haematococcus lacustris

In this study, ultrasonication at a frequency of 40 kHz was used to shorten the sonication period and enhance the growth of Haematococcus lacustris. To confirm the optimal conditions, the effects of ultrasound output and treatment interval were examined. Under optimal conditions (20 W and 15-day cycle), the maximum cell density and chlorophyll content were 66.75 × 104 cells mL−1 and 36.54 mg g−1, respectively, which were increased by 50.00% and 39.01%, respectively, compared to the control. Transmission electron microscopy analysis showed that ultrasonication caused tiny cracks in the W4 and W6 strata but did not disrupt the inner W2 layer. Additionally, RT-qPCR analysis showed that ultrasonication upregulated both cell division and nitrogen uptake. No difference were detected in the composition or quantity of fatty acids. This study demonstrates a novel ultrasonic approach for enhancing the growth of H. lacustris.

Large-Scale Expansion of Human Umbilical Cord-Derived Mesenchymal Stem Cells in a Stirred Suspension Bioreactor Enabled by Computational Fluid Dynamics Modeling.

Human umbilical cord-derived mesenchymal stem cells (hUCMSCs) hold great potential to generate novel and curative cell therapy products. However, the current large-scale cultivation of hUCMSCs is based on empirical geometry-dependent methods, limiting the generation of high-quantity and high-quality hUCMSCs for clinical therapy. Herein, we develop a novel scale-up strategy based on computational fluid dynamics (CFD) to effectively expand the hUCMSCs in a 3D tank bioreactor. Using a standardized hUCMSCs line on microcarriers, we successfully translated and expanded the hUCMSCs from a 200 mL spinner flask to a 1.5 L computer-controlled bioreactor by matching the shear environment and suspending the microcarrier. Experimental results revealed that the batch-cultured hUCMSCs in bioreactors with an agitation speed of 40 rpm shared a more favorable growth and physiological state, similar to that run at 45 rpm in a 200 mL spinner flask, showing comparability in both culture systems. Notably, the maximum cell density reached up to 27.3 × 105 cells/mL in fed-batch culture, 2.9 folds of that of batch culture and 20.2 times of seeding cells. As such, efficient process optimization and scale-up expansion of hUCMSCs were achieved in the microcarrier-based bioreactor system by the developed CFD simulation strategy, which provided an alternative toolbox to generate massive and standardized curative cell therapy products.

Fungal Identification for Microalgae Biomass Hydrolysis using FTIR

Fungi offer a promising avenue for utilizing residual microalgae biomass after lipid extraction, harboring valuable carbohydrates that can be converted into useful compounds, such as sugars. Fourier Transform Infrared Spectroscopy (FTIR) stands out as an effective and environmentally friendly tool for selecting microorganisms with biotechnological potential. This study utilizes FTIR to identify suitable fungal strains for the hydrolysis of microalgae biomass (Desmodesmus subspicatus and Chlorella sp) post-lipid extraction. Eleven fungal strains are selected, applying FTIR and multivariate analysis to choose filamentous fungi. The maximum cell density is 28.7 × 106 cells mL-1 for Chlorella sp. and 15.8 × 106 cells mL-1 for D. subspicatus, with total carbohydrates of 23.1% and 16.9%, respectively. Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) are useful for strain identification. Following the analysis, Penicillium G12 stands out for its ability to utilize D. subspicatus biomass, generating glucose and xylose (sugar yields of 9.4% and 6.6% respectively), and Trichoderma auricularis for Chlorella sp. (sugar yields of 12.9% and 9.6% respectively). FTIR proves successful in detecting fungal strains with biotechnological potential.

Probiotic potential of Tetragenococcus halophilus EFEL7002 isolated from Korean soy Meju

BackgroundProbiotic starters can improve the flavor profile, texture, and health-promoting properties of fermented foods. Tetragenococcus halophilus is a halophilic lactic acid bacterium that is a candidate starter for high-salt fermented foods. However, the species is known to produce biogenic amines, which are associated with neurotoxicity. Here, we report a probiotic starter strain of T. halophilus, EFEL7002, that is suitable for use in high-salt fermentation.ResultsEFEL7002 was isolated from Korean meju (fermented soybean) and identified as T. halophilus, with 99.85% similarity. The strain is safe for use in food as it is a non-hemolytic and non-biogenic amine producer. EFEL7002 is tolerant to gastrointestinal conditions and can adhere to Caco-2 cells. This strain showed antioxidant, anti-inflammatory, and protective effects against the human gut epithelial barrier. EFEL7002 grew well in media containing 0–18% NaCl showing maximum cell densities in 6% or 12% NaCl.ConclusionsT. halophilus EFEL7002 can be used as a health-promoting probiotic starter culture for various salty fermented foods.

Vital evidence for arbuscular mycorrhizal fungi, bacteria and cattail plant to remove Pb-Cd heavy metals from contaminated soils

Phytoremediation is a low-cost but highly efficient and environmentally friendly technology for heavy metal soil remediation. However, its success in soils is dependent on the chosen plant and microbes. Moreover, the effect of mycorrhizal fungi and bacteria on CO2 release, mineralization rate, and metal translocation in cadmium and lead-contaminated cattails plant is unknown. The goal of the research was to look into the effects of bacteria, mycorrhiza, and cattails on CO2 release, mineralization rate, lead (Pb), and cadmium (Cd) removal from soil. The experiment used six different combinations (mycorrhiza, bacillus 10 mL, bacillus 100 mL, mycorrhiza + bacillus 10 mL, mycorrhiza + bacillus 100 mL, and control). The results showed that combining mycorrhiza with bacillus 100 mL resulted in greater increases in CO2 release, polysaccharides content and mineralization rate (2.84 mg CO2 g−1 in dry soil, 0.90 mg, 0.021 mg C g−1 dry soil day−1). More crucially, mycorrhiza + bacillus 100 mL roots had the greatest quantities of Cd and Pb (18.26 mg kg−1 and 155.22 mg kg−1), showing that bacteria had a prominent part in the phytoextraction process. Regarding Cd, the bacillus 100 mL had the highest translocation factor (TF) (3.99) and biological accumulation factor (BAF) (75.54), indicating effective translocation and excessive Cd accumulation in the plant. Bacillus 100 and mycorrhiza + bacillus 100 had the highest Pb TF (0.49) and BAF (6.08). Ultimately, the elimination of Cd and Pb was linked to the maximum bacterial cell density, mycorrhizal activity, and CO2 emission, resulting in a unique phytoremediation in Pb-Cd contaminated cattails rhizosphere soils.

Distinct physiological responses of Coccolithus braarudii life cycle phases to light intensity and nutrient availability

ABSTRACT Coccolithophores feature a haplo-diplontic life cycle comprised of diploid cells producing heterococcoliths and haploid cells producing morphologically different holococcoliths. These life cycle phases of each species appear to have distinct spatial and temporal distributions in the oceans, with the heavily calcified heterococcolithophores (HET) often more prevalent in winter and at greater depths, whilst the lightly calcified holococcolithophores (HOL) are more abundant in summer and in shallower waters. The haplo-diplontic life cycle may therefore allow coccolithophores to expand their ecological niche, switching between life cycle phases to exploit conditions that are more favourable. However, coccolithophore life cycles remain poorly understood and fundamental information on the physiological differences between life cycle phases is required if we are to better understand the ecophysiology of coccolithophores. In this study, we have examined the physiology of HET and HOL phases of the coccolithophore Coccolithus braarudii in response to changes in light and nutrient availability. We found that the HOL phase was more tolerant to high light than the HET phase, which exhibited defects in calcification at high irradiances. The HET phase exhibited defects in coccolith formation under both nitrate (N) and phosphate (P) limitation, whilst no defects in calcification were detected in the HOL phase. The HOL phase grew to a higher cell density under P-limitation than N-limitation, whereas no difference was observed in the maximum cell density reached by the HET phase at these nutrient concentrations. HET cells grown under a light:dark cycle divided primarily in the dark and early part of the light phase, whereas HOL cells continued to divide throughout the 24 h period. The physiological differences may contribute to the distinct biogeographic distributions observed between life cycle phases, with the HOL phase potentially better adapted to high light, low nutrient regimes, such as those found in seasonally stratified surface waters. HIGHLIGHTS Coccolithus braarudii life cycle phases exhibit different physiological responses. The heavily calcified heterococcolithophores (HET) life cycle phase is more sensitive to high light. The lightly calcified holococcolithophores (HOL) life cycle phase may be better suited to growth under low phosphate availability.

Pretreatment of Jerusalem artichoke stalk using hydroxylammonium ionic liquids and their influences on 2,3-butanediol fermentation by Bacillus subtilis

Pretreatment of lignocellulose is a vital step for biological production of bio-chemicals and bio-fuels. In this work, the pretreatment of Jerusalem artichoke stalk (JAS) by hydroxylammonium ionic liquids was evaluated based on pretreatment efficiency including polysaccharide recovery and enzymatic digestibility, and influence of ionic liquids on 2,3-butanediol fermentation using Bacillus subtilis. The results showed ethanolammonium acetate (EOAA) was efficient in JAS pretreatment, and maximum cell density was increased 25% when EOAA concentration was not greater than 0.3 mol/L in medium, while the total concentration of acetoin and 2,3-butanediol was 15% greater than the control at 0.1 mol/L EOAA. After the pretreatment under optimized conditions of 170 °C for 5-h and liquid–solid ratio of 18, about 87% cellulose and 75% hemicellulose were recovered, and glucose yield of 64% and xylose of 66% were obtained after 24-h hydrolysis of JAS residue by cellulase (15 FPU/g) with solid loading of 10 wt%.

Evaluation of microtiter plate as a high-throughput screening platform for beer fermentation

AbstractDownscaling the anaerobic fermentation in a microtiter plate (MTP) facilitates high throughput screening (HTS) applications. This study investigates the impacts of MTP configurations (scale, shaking, and cover) on the S. pastorianus beer fermentation compared to that in the shaking flask (SF) and European Brewing Convention (EBC) tube regarding fermentation performances and flavor attributes. The lager strains in MTPs accelerated cells reproduction and vitalization, sugar consumption, and glycerol accumulation. The microscale beer fermentation was closer to the SF but differed greatly from EBC tube fermentation depending on the MTP configurations. The downscaling from 2 mL to 0.2 mL in MTP increased the cell growth rate and vitality but did not change the maximum cell density. The shaking MTP did not promote early growth but sustained significantly higher cell numbers at the later fermentation stage. More than 1.5-folds acetaldehyde and higher alcohols, yet less than half esters, were obtained from the MTP and SF fermentations relative to that in the EBC tube. The air-tight MTP cover, as compared to the gas-permeable cover, not only balanced the above volatile flavors but also maintained integrity to the endogenous carbon dioxide pressure during beer fermentation. Additionally, fermentative activities were reduced by excluding air in either the material or the headspace of MTP. Hence, MTP configurations influenced S. pastorianus beer fermentation. These influences were partly attributed to their impacts on air accessibility. Conscious of the impacts, this study helps interpret the minimized fermentation and sheds light on the development of MTP based HTS platform for anaerobic cultivations.

Mass cultivation of marine diatoms using local salts and its impact on growth and productivity

Diatoms are of great interest for many biotechnological applications. The present study highlights the comparative analysis for mass cultivation under the effect of seawater made from table salt (TS), rock salt (RS), and synthetic seawater in the presence of normal silica and induction coupled plasma (ICP) nanosilica (Nano Si) for inducing diatom growth. Out of all the test formulations, RS-f/2 Nano Si showed the best results with maximum cell density (3.16x107±0.04 and 3.24x107±0.05 cells mL−1), carbohydrate (403.0±3.4 and 398.0±8.1 mg g−1), and chrysolaminarin yield (66.2±5.5 and 49.3±5.1 mg g−1) in both Chaetoceros gracilis and Thalassiosira weissflogii respectively. The presence of a rich pigment profile and lipids further highlights the importance of TS and RS for cost-effective mass culturing. Results reveal that mass cultivation of marine diatoms with TS and RS in the presence of nanosilica not only reduces costs but also enhances metabolite production.

Spatio-temporal variations of phytoplankton assemblage in coastal waters of Maharashtra, north-eastern Arabian Sea

Seasonal variations in phytoplankton species and abundance along the coast of Maharashtra from two different locations (Mumbai and Ratnagiri) and depths were investigated during August 2014-May 2017. A total of 84 species of phytoplankton were recorded from the region out of which 67 were diatoms, 16 dinoflagellates and one blue green alga. Seventy-five and 60 species of phytoplankton were recorded from Ratnagiri and Mumbai respectively. Diatoms dominated the phytoplankton community (81.7-93.3%) followed by dinoflagellates (4.7-7.2%) and blue green algae in both locations. Maximum phytoplankton density was recorded during post-monsoon season followed by pre-monsoon and monsoon seasons at Mumbai and Ratnagiri. Highest average phytoplankton cell density recorded was 9.09 x 104 cells l-1 and 4.06 x 104 cells l-1 during post-monsoon season at Ratnagiri and Mumbai respectively. Maximum cell density was observed at 20 m depth from Mumbai and Ratnagiri. Thalassiosira subtilis, Trieres mobiliensis, Skeletonema costatum, Coscinodiscus centralis and Ditylum brightwelli were the most abundant phytoplankton species recorded at Mumbai, whereas Chaetoceros curvisetus, S. costatum, Trichodesmium erythraeum, Chaetoceros lorenzianus and Ditylum brightwelli were abundant in Ratnagiri waters. The blue green alga, T. erythraeum was abundantly recorded during pre-monsoon season. Species diversity index (H’) ranged from 4.72 to 5.52 and was higher during post-monsoon season compared to pre-monsoon and monsoon. Highest phytoplankton diversity was observed at 20 m depth compared to 40 m depth.Keywords: Arabian Sea, Diversity, Mumbai, Phytoplankton, Ratnagiri

SINGLE CELL PROTEIN PRODUCTION FROM PLANTAIN AND BANANA PEELS

The fermentative ability of Saccharomyces cerevisiae to grow and produce biomass protein from pretreated plantain and banana peels as substrate was studied. Plantain peels had a moisture content of 6.95±0.05%, ash (22.33±0.01%), protein (7.10±0.10%), fat (6.18±0.04%), crude fibre (13.99±0.20%) and carbohydrate (43.45±0.10%). The banana peels had corresponding values of 6.70±0.00%, 8.45±0.02%, 4.90±0.05%, 1.65±0.01%, 11.70±0.10% and 66.60±0.70% in that order. During fermentation the pH decreased from 4.1 to 2.3 and 2.5 in the plantain and banana peel media, while the titratable acidity increased from 0.7 to 4.1 and 3.5 in the plantain and banana peel media respectively. There was a higher yield of biomass with the plantain peels which gave a maximum cell density of 2.973 (OD) on the 7th day compared to the banana peels which reached the peak on the 7th day with a maximum cell density of 2.492.The yeast population increased during the fermentation period from 6.69Log10cfu/ml to 7.58Log10cfu/ml in the plantain and 6.69Log10cfu/ml to 7.53Log10cfu/ml in banana peel media respectively. The dry mass of S. cerevisiae harvested from plantain and banana peel medium per 100 ml were 2.71±0.01g and 4.28±0.06g with protein contents of 13.95±0.71% and 11.70±0.50% with plantain peel media having the higher yield

Monoraphidium sp. IBASU-A 574 (Selenastraceae, Chlorophyta) – перспективний продуцент біомаси для біоенергетики

he present studies were carried out to evaluate a potential biofuel application of the native strain Monoraphidium sp. IBASU-A 574 (Selenastraceae, Chlorophyta) adapted to the temperate zone climatic conditions. This strain was isolated from a small freshwater lake situated in Kyiv-city (Ukraine) by the reached culture method for obtaining desired strains of different species with high growth rate. It was identified based on its morphological characterization under light microscopy and 18S rRNA sequence analysis. Its culture’s growth, kinetic characteristics (specific growth rate and productivity) and biological peculiarities of the investigated strain were studied in comparison with the well-known biomass producer Chlorella vulgaris Beijer. CALU 157 under the same autotrophic cultivating conditions with using the modified Tamiya medium. It was established an active growth of Monoraphidium sp. IBASU-A 574 which was practically equal to the well-known producer and characterized by following parameters: a maximum cell density of 248 ∙ 10-6 cells ∙ mL-1, the specific growth rate of 1.4 days-1 and productivity of 72.5 ∙ 10-6 cells ∙ mL-1 ∙ days-1. The results of gas-liquid chromatography analysis showed that a fatty acid profile of this microalga included a complex of palmitic (C16: 0), oleic (C18: 1), linoleic (C18: 2) and linolenic (C18: 3) major fatty acids with suitable proportion for developing biodiesel feedstocks. Moreover, there was considerable variation in formation of its fatty acid composition depending on the stage of growth, that confirmed the necessity for such studies to determine both optimal time for growing algae and gaing maximum yield of target products. Thus, Monoraphidium sp. IBASU-A 574 was found to be the promising producer of biomass for bioenergetic industry due to obtained data of its growth characteristics and suitable fatty acid profile of lipids.

Isolation, identification, and optimization of growth conditions for the marine microalgae isolated from the Gulf of Mannar, South-east coast of India

Marine microalgae were isolated from the selected locations from the coastal waters of Gulf of Mannar during December 2019 to February 2021. A total of 16 microalgal species were collected and identified morphologically using a light microscope with image capture system. Of these, five pure isolates of three pennate diatoms viz., Cylindrotheca fusiformis, Amphora sp., and Navicula clavata, and two species of green algae (Nannochloropsis salina and Chlorella sp.) were identified morphologically by field-emission scanning electron microscopy (FE-SEM) and confirmed by PCR amplification sequence analysis of 18S rRNA. The isolates confirmed by PCR were C. fusiformis, Amphora sp., N. clavata, and N. salina whereas Chlorella sp., was confirmed through FE-SEM. Optimization of culture conditions for the identified microalgae was studied with different culture media (Diatom Artificial Medium (DAM), F/2 medium, and Walne’s medium) by various salinities to assess their best growth for commercial application. At 30 ppt salinity, the maximum cell density of C. fusiformis observed in DAM was 7.63 × 106 cells/mL, whereas Amphora sp. and N. clavata showed maximum cell density of 1.20 × 106 and 1.35 × 106 cells/mL, respectively, in F/2 medium. At 35 ppt salinity, maximum cell density of Chlorella sp. was 12.1 × 106 cells/mL in the F/2 medium. Similarly, the maximum growth of 13.7 × 106 cells/mL was obtained at 35 ppt salinity for N. salina in Walne’s medium. As the microalgal strains were isolated at succession stage, they can tolerate a wide range of environmental conditions and could be mass produced in outdoor conditions for industrial applications